An 8051 microcontroller comes bundled with the following features − 4KB bytes on-chip program memory (ROM) 128 bytes on-chip data memory (RAM) Four register banks 128 user defined software flags 8-bit bidirectional data bus 16-bit unidirectional address bus 32 general purpose registers each of 8-bit 16 bit Timers (usually 2, but may have more or less) Three internal and two external Interrupts Four 8-bit ports,(short model have two 8-bit ports) 16-bit program counter and data pointer 8051 may also have a number of special features such as UARTs, ADC, Op-amp, etc.
Explain this in simple words?
The 8051 microcontroller is a small computer on a single integrated circuit. It has the following main features:
Overall 8051 microcontroller is a versatile and capable component that can be programmed to control different electronic devices and systems.
The 8051 has a flag register to indicate arithmetic conditions such as the carry bit. The flag register in the 8051 is called the program status word (PSW) register. The program status word (PSW) register is an 8-bit register. It is also referred to as the flag register. Although the PSW register is 8 bits wide, only 6 bits of it are used by the 8051. The two unused bits are user-definable flags. Four of the flags are called conditional flags, meaning that they indicate some conditions that result after an instruction is executed. These four are CY (carry) AC (auxiliary carry) P (parity) OV (overflow).
The 8051 microcontroller uses a flag register, also known as Program Status Word (PSW) register, to indicate different arithmetic conditions such as carry, auxiliary carry, parity, and overflow. The PSW register is an8-bit register, but only 6 of its bits are used by the 8051 leaving 2 bits available for user-defined flags. The conditional flags in the PSW register, which indicate specific conditions after an instruction is executed, are CY (carry), AC (auxiliary carry), P (parity), and OV (overflow). These flags play a crucial role in the flow of program execution and making decisions based on the results of arithmetic operations.
CY, the carry flag This flag is set whenever there is a carry out from the D7 bit. This flag bit is affected after an 8-bit addition or subtraction. It can also be set to 1 or 0 directly by an instruction such as “SETB C” and “CLR C” where “SETB C” stands for “set bit carry” and “CLR C” for “clear carry”. AC, the auxiliary carry flag If there is a carry from D3 to D4 during an ADD or SUB operation, this bit is set; otherwise, it is cleared. This flag is used by instructions that perform BCD (binary coded decimal) arithmetic. P, the parity flag The parity flag reflects the number of 1 s in the A (accumulator) register only. If the A register contains an odd number of Is, then P = 1. Therefore, P = 0 if A has an even number of Is. OV, the overflow flag This flag is set whenever the result of a signed number operation is too large, causing the high-order bit to overflow into the sign bit. In general, the carry flag is used to detect errors in unsigned arithmetic operations. The overflow flag is only used to detect errors in signed arithmetic operations
The flags in the 8051 microcontroller play a vital role in indicating specific conditions after arithmetic operations. Here's a summary of each flag:
Carry Flag (CY): This flag is set when there's a carry out from the D7 bit, after an 8-bit addition or subtraction. It can also be directly set or cleared using instructions like "SETB C" (set bit carry) and "CLR C" (clear carry). This flag is mainly used to detect errors in unsigned arithmetic operations.
Auxiliary Carry Flag (AC): The AC flag is set if there is a carry from D3 to D4 during an ADD or SUB operation, otherwise it's cleared. It is specifically used by instructions that perform binary-coded decimal (BCD) arithmetic.
Parity Flag (P): This flag reflects the number of 1s in the A (accumulator) register only. If the A register contains an odd number of 1s, then P = 1. Otherwise, P = 0. It helps in determining the parity of the value in the accumulator register.
Overflow Flag (OV): The OV flag is set when the result of a signed number operation is too large, causing the high-order bit to overflow into the sign bit. It is used to detect errors in signed arithmetic operations.
These flags are crucial for decision making and error detection in various arithmetic operations performed by the 8051 microcontroller.
explain parity and overflow only clearly
Certainly! Here's a clear explanation of parity and overflow in the context of the 8051 microcontroller:
Parity: The parity flag in the 805 microcontroller reflects the number of 1s in the A (accumulator) register. If the register contains an odd number of 1s, then the parity flag (P) is set to 1. Conversely, if the A register has an even number of 1s, then parity flag is set to 0. This flag helps in determining the parity of the in the accumulator register and is used for various data processing and error checking purposesOverflow: The overflow flag in the 8051 microcontroller is set when the result of a signed number operation is too large, causing the high-order bit to overflow into the sign bit. It is specifically used to detect errors in signed arithmetic operations. When an arithmetic operation results in a value exceeds the capacity of the register to hold it, the overflow flag is set, indicating that the result cannot be represented accurately within given bit width. This flag is important for ensuring accurate processing of signed numbers and preventing errors due to arithmetic overflow.
I this explanation clarifies the concepts of parity and overflow in the context of the 8051 microcontroller.
Central Processor Unit (CPU)
As we know that the CPU is the brain of any processing device of the microcontroller. It monitors and controls all operations that are performed on the Microcontroller units. The User has no control over the work of the CPU directly . It reads program written in ROM memory and executes them and do the expected task of that application.
Interrupts
As its name suggests, Interrupt is a subroutine call that interrupts of the microcontrollers main operations or work and causes it to execute any other program, which is more important at the time of operation. The feature of Interrupt is very useful as it helps in case of emergency operations. An Interrupts gives us a mechanism to put on hold the ongoing operations, execute a subroutine and then again resumes to another type of operations.
The Microcontroller 8051 can be configured in such a way that it temporarily terminates or pause the main program at the occurrence of interrupts. When a subroutine is completed, Then the execution of main program starts. Generally five interrupt sources are there in 8051 Microcontroller. There are 5 vectored interrupts are shown in below
INTO TFO INT1 TF1 R1/T1 Out of these, (INT0) ̅ and (INT1) ̅ are external interrupts that could be negative edge triggered or low level triggered. When All these interrupts are activated, set the corresponding flogs except for serial interrupt,.The interrupt flags are cleared when the processor branches to the interrupt service routine (ISR). The external interrupt flags are cleared when the processor branches to the interrupt service routine, provides the interrupt is a negative edge triggered whereas the timers and serial port interrupts two of them are external interrupts, two of them are timer interrupts and one serial port interrupt terminal in general.
The Central Processing Unit (CPU) is indeed the control center of a microcontroller, carrying out and supervising all operations. It reads programs from ROM memory and executes the instructions to perform the desired tasks of the application. Users typically do not have direct control over the CPU's functionality.
Interrupts, as implied by the name, are subroutine calls that temporarily halt the microcontroller's ongoing operations to execute another, more critical program. They are a valuable feature for handling emergency operations, permitting the suspension of current tasks to run a subroutine before continuing with other operations. The 8051 Microcontroller can be configured to pause the main program upon the occurrence of interrupts. Once the subroutine is completed, the main program resumes.
The 8051 Microcontroller has five vectored interrupts, including INTO, TFO, INT1, TF1, and R1/T1. Among these, INT0 and INT1 are external interrupts that can be triggered by negative edges or low levels. When these interrupts are activated, the corresponding flags are set, except for the serial interrupt. The interrupt flags are cleared when the processor branches to the interrupt service routine (ISR). In the case of external interrupts, the flags are cleared when the processor branches to the ISR, provided that the interrupt is negative edge-triggered. Additionally, the microcontroller features two timer interrupts and one serial port interrupt.
explain the block diagram of 8051 microcontroller
Sure, the block diagram of the 8051 microcontroller can be described as follows:
CPU: The central processing unit performs all arithmetic and logical operations and controls the overall functioning of the microcontroller.
RAM: This is the random access memory used for temporary data storage during program execution.
ROM: The read-only memory stores the program and fixed data, which remains intact even when the power is turned off.
I/O Ports: These provide interfaces for connecting external devices and peripherals, allowing data transfer to and from the microcontroller.
Timers/Counters: These are utilized for timing and counting external events and controlling the microcontroller's timing-dependent operations.
Serial Communication: The 8051 microcontroller has a built-in UART (Universal Asynchronous Receiver Transmitter) for serial communication.
Interrupt Control: This unit handles internal and external interrupts, allowing the microcontroller to respond to critical events promptly.
Oscillator and Clock Circuit: This component generates the system clock, essential for synchronizing the microcontroller's internal operations.
These blocks collectively form the 8051 microcontroller, and each plays a significant role in its operation and capability.
Memory Microcontroller requires a program which is a collection of instructions. This program tells microcontroller to do specific tasks. These programs require a memory on which these can be saved and read by Microcontroller to perform specific operations of a particular task. The memory which is used to store the program of the microcontroller is known as code memory or Program memory of applications. It is known as ROM memory of microcontroller also requires a memory to store data or operands temporarily of the micro controller. The data memory of the 8051 is used to store data temporarily for operation is known RAM memory. 8051 microcontroller has 4K of code memory or program memory,that has 4KB ROM and also 128 bytes of data memory of RAM.
BUS Basically Bus is a collection of wires which work as a communication channel or medium for transfer of Data. These buses consists of 8, 16 or more wires of the microcontroller. Thus, these can carry 8 bits,16 bits simultaneously. Hire two types of buses that are shown in below
Address Bus Data Bus Address Bus: Microcontroller 8051 has a 16 bit address bus for transferring the data. It is used to address memory locations and to transfer the address from CPU to Memory of the microcontroller. It has four addressing modes that are
Immediate addressing modes. Bank address (or) Register addressing mode. Direct Addressing mode. Register indirect addressing mode. Data Bus: Microcontroller 8051 has 8 bits of the data bus, which is used to carry data of particular applications.
Oscillator
Generally, we know that the microcontroller is a device, therefore it requires clock pulses for its operation of microcontroller applications. For this purpose, microcontroller 8051 has an on-chip oscillator which works as a clock source for Central Processing Unit of the microcontroller. The output pulses of oscillator are stable. Therefore, it enables synchronized work of all parts of the 8051 Microcontroller.
Input/Output Port
Normally microcontroller is used in embedded systems to control the operation of machines in the microcontroller. Therefore, to connect it to other machines, devices or peripherals we require I/O interfacing ports in the microcontroller interface. For this purpose microcontroller 8051 has 4 input, output ports to connect it to the other peripherals
Timers/Counters
8051 microcontroller has two 16 bit timers and counters. These counters are again divided into a 8 bit register. The timers are used for measurement of intervals to determine the pulse width of pulses.
The microcontroller necessitates a program comprising instructions that direct its. This program is stored in memory, known as code memory or program memory, also referred to as ROM memory. The microcontroller also requires data memory, known as RAM memory, to temporarily store during operation. The 8051 microcontroller has 4KB of for program storage and 128 bytes of RAM for temporary data storage.
The bus is a communication channel or medium for data transfer, consisting of a collection of wires. The 8051 microcontroller has two types of buses:
The on-chip oscillator in the 8051 microcontroller serves as clock source for the CPU, providing stable clock pulses for synchronized operation.
For interfacing with external devices or peripherals, the 8051 microcontroller includes 4 input/output ports.
Additionally, the 8051 microcontroller incorporates two 16-bit timers/counters, which can also be divided into 8-bit registers. These timers are utilized for interval measurement and pulse width determination.
Oscillator
Generally, we know that the microcontroller is a device, therefore it requires clock pulses for its operation of microcontroller applications. For this purpose, microcontroller 8051 has an on-chip oscillator which works as a clock source for Central Processing Unit of the microcontroller. The output pulses of oscillator are stable. Therefore, it enables synchronized work of all parts of the 8051 Microcontroller.
Input/Output Port
Normally microcontroller is used in embedded systems to control the operation of machines in the microcontroller. Therefore, to connect it to other machines, devices or peripherals we require I/O interfacing ports in the microcontroller interface. For this purpose microcontroller 8051 has 4 input, output ports to connect it to the other peripherals
Timers/Counters
8051 microcontroller has two 16 bit timers and counters. These counters are again divided into a 8 bit register. The timers are used for measurement of intervals to determine the pulse width of pulses.
The 8051 microcontroller incorporates an on-chip oscillator, as a stable clock source for the Central Processing Unit (CPU). This oscillator provides the required clock pulses for the synchronized operation of all components within the microcontroller.
To enable microcontroller to interface with external machines, devices, or peripherals, the 8051 microcontroller is equipped with 4 input/output ports.
Additionally, the 8051 microcontroller features two 16-bit timers and counters, which can be further divided into 8-bit registers. These timers are utilized for interval measurement and determining the pulse width of signals.
Description of the Pins :
Pin 1 to Pin 8 (Port 1) – Pin 1 to Pin 8 are assigned to Port 1 for simple I/O operations. They can be configured as input or output pins depending on the logic control i.e. if logic zero (0) is applied to the I/O port it will act as an output pin and if logic one (1) is applied the pin will act as an input pin. These pins are also referred to as P1.0 to P1.7 (where P1 indicates that it is a pin in port 1 and the number after ‘.’ tells the pin number i.e. 0 indicates first pin of the port. So, P1.0 means first pin of port 1, P1.1 means second pin of the port 1 and so on). These pins are bidirectional pins. Pin 9 (RST) – Reset pin. It is an active-high, input pin. Therefore if the RST pin is high for a minimum of 2 machine cycles, the microcontroller will reset i.e. it will close and terminate all activities. It is often referred as “power-on-reset” pin because it is used to reset the microcontroller to it’s initial values when power is on (high). Pin 10 to Pin 17 (Port 3) – Pin 10 to pin 17 are port 3 pins which are also referred to as P3.0 to P3.7. These pins are similar to port 1 and can be used as universal input or output pins. These pins are bidirectional pins. These pins also have some additional functions which are as follows: P3.0 (RXD) : 10th pin is RXD (serial data receive pin) which is for serial input. Through this input signal microcontroller receives data for serial communication. P3.1 (TXD) : 11th pin is TXD (serial data transmit pin) which is serial output pin. Through this output signal microcontroller transmits data for serial communication. P3.2 and P3.3 (INT0′, INT1′ ) : 12th and 13th pins are for External Hardware Interrupt 0 and Interrupt 1 respectively. When this interrupt is activated(i.e. when it is low), 8051 gets interrupted in whatever it is doing and jumps to the vector value of the interrupt (0003H for INT0 and 0013H for INT1) and starts performing Interrupt Service Routine (ISR) from that vector location. P3.4 and P3.5 (T0 and T1) : 14th and 15th pin are for Timer 0 and Timer 1 external input. They can be connected with 16 bit timer/counter. P3.6 (WR’) : 16th pin is for external memory write i.e. writing data to the external memory. P3.7 (RD’) : 17th pin is for external memory read i.e. reading data from external memory. Pin 18 and Pin 19 (XTAL2 And XTAL1) – These pins are connected to an external oscillator which is generally a quartz crystal oscillator. They are used to provide an external clock frequency of 4MHz to 30MHz. Pin 20 (GND) – This pin is connected to the ground. It has to be provided with 0V power supply. Hence it is connected to the negative terminal of the power supply. Pin 21 to Pin 28 (Port 2) – Pin 21 to pin 28 are port 2 pins also referred to as P2.0 to P2.7. When additional external memory is interfaced with the 8051 microcontroller, pins of port 2 act as higher-order address bytes. These pins are bidirectional. Pin 29 (PSEN) – PSEN stands for Program Store Enable. It is output, active-low pin. This is used to read external memory. In 8031 based system where external ROM holds the program code, this pin is connected to the OE pin of the ROM. Pin 30 (ALE/ PROG) – ALE stands for Address Latch Enable. It is input, active-high pin. This pin is used to distinguish between memory chips when multiple memory chips are used. It is also used to de-multiplex the multiplexed address and data signals available at port 0. During flash programming i.e. Programming of EPROM, this pin acts as program pulse input (PROG). Pin 31 (EA/ VPP) – EA stands for External Access input. It is used to enable/disable external memory interfacing. In 8051, EA is connected to Vcc as it comes with on-chip ROM to store programs. For other family members such as 8031 and 8032 in which there is no on-chip ROM, the EA pin is connected to the GND. Pin 32 to Pin 39 (Port 0) – Pin 32 to pin 39 are port 0 pins also referred to as P0.0 to P0.7. They are bidirectional input/output pins. They don’t have any internal pull-ups. Hence, 10 K? pull-up registers are used as external pull-ups. Port 0 is also designated as AD0-AD7 because 8051 multiplexes address and data through port 0 to save pins. Pin 40 (VCC) – This pin provides power supply voltage i.e. +5 Volts to the circuit.
The pins of the 8051 microcontroller can be described as follows:
Pins 1 to 8 ( 1): These pins are assigned to Port 1 for simple input/output operations. They can be configured as input or output pins based on the logic control. Referred to as P1.0 to P.7.
Pin 9 (RST): This is the pin, an active-high input pin used to reset the microcontroller when held high for a minimum of 2 machine cycles.
Pins 10 to 17 (Port 3): to Port 1, these are universal input/output bidirectional pins. Additionally, they have functions such as serial data receive (RXD), serial data transmit (TXD), external hardware interrupts (INT0 and INT1), external inputs (T0 T1), external memory write (WR'), and external memory (RD').
Pins 18 and 19 (XTAL2 and XTAL1): Connected to external oscillator, typically a quartz crystal oscillator, to provide an clock frequency.
Pin 20 (GND): Connected to the ground, providing 0V power supply.
Pins to 28 (Port 2): Also bidirectional, these pins act as higher-order address bytes when additional external memory is interfaced with the microcontroller.
Pin 29 (PSEN): Program Store Enable an output, active-low pin used to read external memory.
Pin 30 (ALE/PROG Address Latch Enable, used to distinguish between memory chips when multiple memory chips are employed. flash programming, this pin acts as a program pulse input.
Pin 31 (EA/VPP): External Access input, utilized enable/disable external memory interfacing. In the 8051, EA is connected to V for on-chip ROM. In other family members, such as 8031 and 8032 where there is no on-chip ROM, the EA pin connected to the ground.
Pins 32 to 39Port 0): These bidirectional input/output pins are also designated as AD0-AD7. Port 0 multiplexes address and data to conserve pins.
Pin 40 (V): Provides the power supply voltage, typically +5 Volts the circuit.
Although the DPTR register is 16-bit, it can also be accessed as two 8-bit registers, DPH and DPL, where DPH is the high byte and DPL is the low byte. In this addressing mode, the source operand is a constant. In immediate addressing mode, as the name implies, when the instruction is assembled, the operand comes immediately after the opcode. Notice that the immediate data must be preceded by the pound sign, “#”. This addressing mode can be used to load information into any of the registers, including the DPTR register.
In the immediate addressing mode, the source operand is indeed a constant. When using this addressing mode, the operand immediately follows the opcode, and the immediate data must be preceded by the pound sign, "#" during assembly. This mode allows for the loading of information into any of the registers, including the DPTR register, effectively facilitating quick access to constant values for operations. The 16-bit DPTR register can also be accessed as two 8-bit registers, DPH and DPL, where DPH represents the high byte and DPL represents the low byte, allowing for more flexible handling of data.
what is operand here "MOV A, #25H"?
In the instruction "MOV A, #25H", the operand "#25H". This is a constant value (immediate data) that being moved into the accumulator (A). The "#" symbol denotes immediate addressing mode, indicating that the value following it a constant to be used in the instruction. Therefore, in this context, the operand "#25H" represents the immediate data being loaded into the accumulator.
There are 128 bytes of RAM in the 8051. The RAM has been assigned addresses 00 to 7FH. The following is a summary of the allocation of these 128 bytes. RAM locations 00 – 1FH are assigned to the register banks and stack. RAM locations 20 – 2FH are set aside as bit-addressable space to save single bit data. RAM locations 30 – 7FH are available as a place to save byte-sized data. Although the entire 128 bytes of RAM can be accessed using direct addressing mode, it is most often used to access RAM locations 30 – 7FH. This is due to the fact that register bank locations are accessed by the register names of RO – R7, but there is no such name for other RAM locations. In the direct addressing mode, the data is in a RAM memory location whose address is known, and this address is given as a part of the instruction. Contrast this with immediate addressing mode, in which the operand itself is provided with the instruction. The “#” sign distinguishes between the two modes.
In the 8051 microcontroller, the 128 bytes of RAM are as follows:
RAM locations 00 – 1FH: These are designated for the register banks and stack.
RAM locations 20 – 2: This space is reserved as bit-addressable, allowing for the storage of single bit data.
RAM locations 30 – 7FH: This area is available for the of byte-sized data.
Although the entire 128 bytes of RAM can be accessed using direct addressing mode, it is more common to utilize the RAM locations 30 –7FH due to the fact that register bank locations are accessed the register names RO – R7, while there are no specific register names assigned for the other RAM locations.
In direct addressing mode, data is accessed in a RAM memory location whose address is known, and this address is specified as part of the instruction. This is in contrast to immediate addressing mode, where the operand itself is provided with the instruction, and the "#" sign distinguishes between the two modes.
Among the registers we have discussed so far, we have seen that RO – R7 are part of the 128 bytes of RAM memory. What about registers A, B, PSW, and DPTR? Do they also have addresses? The answer is yes. In the 8051, registers A, B, PSW, and DPTR are part of the group of registers commonly referred to as SFR. There are many special function registers and they are widely used. The SFR can be accessed by their names (which is much easier) or by their addresses. For example, register A has address EOH, and register B has been designated the address FOH
Yes, registers A, B, PSW, and DPTR the 8051 microcontroller are part of the special function registers (SFR). These special function registers are essential components of the 8051 microcontroller, and they have specific addresses assigned to them. The SFR can be accessed by their, which is more convenient, or by their addresses. For example, register A has the address E0H, and register B has been designated the address0H. These addresses allow for direct access to and manipulation of the data stored in these registers, which are crucial for controlling the behavior and operation of the microcontroller.
In the register indirect addressing mode, a register is used as a pointer to the data. If the data is inside the CPU, only registers RO and Rl are used for this purpose. In other words, R2 – R7 cannot be used to hold the address of an operand located in RAM when using this addressing mode. When RO and Rl are used as pointers, that is, when they hold the addresses of RAM locations, they must be preceded by the “@” sign
In the register indirect addressing mode, a register is utilized as a pointer to access the data. Specifically, when the data is within the CPU, only registers R0 and R1 are employed for this purpose. This means that R2 – R7 cannot be used to store the address of an operand located in RAM when using register indirect addressing mode.
When R0 and R1 are used as pointers, signified by their holding of RAM addresses, they must be preceded by the "@" sign in the instruction. This allows for the effective access and manipulation of data stored in the RAM using the register indirect addressing mode.
One of the advantages of register indirect addressing mode is that it makes accessing data dynamic rather than static as in the case of direct addressing mode. The Example, two cases of copying 55H into RAM locations 40H to 45H. Notice in solution (b) that there are two instructions that are repeated numerous times. We can create a loop with those two instructions as shown in solution (c). Solution (c) is the most efficient and is possible only because of register indirect addressing mode. Looping is not possible in direct addressing mode. This is the main difference between the direct and register indirect addressing modes.
The register indirect addressing mode offers the advantage of dynamic data access, as opposed to the static access provided by the direct addressing mode. For instance, let's consider the example of copying the value 55H into RAM locations 40H to 45H.
In solution (b), there are two instructions that are repeated multiple times, resulting in a less efficient approach. However, by utilizing register indirect addressing mode, we can create a loop with those two instructions, as demonstrated in solution (c). This loop is the most efficient and is achievable only because of register indirect addressing mode. It's important to note that looping is not possible in direct addressing mode. This exemplifies the key difference between direct and register indirect addressing modes in terms of their ability to facilitate efficient and dynamic data handling.
Indexed addressing mode is widely used in accessing data elements of look-up table entries located in the program ROM space of the 8051. The instruction used for this purpose is “MOVC A, @A+DPTR”. The 16-bit register DPTR and register A are used to form the address of the data element stored in on-chip ROM. Because the data elements are stored in the program (code) space ROM of the 8051, the instruction MOVC is used instead of MOV. The “C” means code. In this instruction the contents of A are added to the 16-bit register DPTR to form the 16-bit address of the needed data.
Indexed addressing mode is indeed widely employed for accessing data elements of look-up table entries located in the program ROM space of the 8051 microcontroller. The instruction "MOVC A, @A+DPTR" is specifically utilized for this purpose. In this operation, the 16-bit register DPTR and register A are utilized to compose the address of the data element stored in the on-chip ROM. It's important to note that as the data elements are stored in the program (code) space ROM of the 8051, the instruction MOVC is used instead of MOV. The letter "C" here signifies "code". Within this instruction, the contents of A are added to the 16-bit register DPTR to form the 16-bit address of the required data.
This method allows for efficient and optimized retrieval of data elements from the ROM, a crucial function often employed in microcontroller designs.
The scheduling algorithms of real-time operating systems (RTOS), they can run tasks in such a way that leaves the impression of a multitasking behavior. • This is achieved by giving the RTOS the capability to interrupt a currently executing task and to start executing another one. • At some point in time, the interrupted task should resume its operation. • When that occurs the microprocessor must be put in the same state as it was the last time the interrupted task was being executed. • This is done using a mechanism called context switching. • Each task uses a specific set of resources when it is executing. • These include CPU registers, system status flags, access to memory (heap, stack), etc..
explain this in simple words
Real-time operating systems (RTOS) use scheduling algorithms to handle tasks, making it seem like they are doing multiple things at once. This possible because the RTOS can pause a task that's running and start working on another one. But at some point, the first task needs to continue where it left off. To make this happen smoothly, the microprocessor needs to be set up just like it was when first task was running. This process is called context switching.
Each task uses specific resources, like areas in the computer's memory and CPU settings, while it's running. These resources need to be saved and restored correctly during context switching so that tasks can smoothly carry from where they left off.
IO Interfacing • Input-output interface provides a method for transferring information between internal storage and external I/O devices. • Peripherals connected to a microcontroller need special communication links for interfacing them with the CPU. The purpose of the communication link is to resolve the differences that exist between the CPU and each peripheral. • The major differences are: – Peripherals are electromechanical and electromagnetic devices and their manner of operation is different from the operation of the CPU and memory, which are electronic devices. Therefore, a conversion of signal values may be required. – The data transfer rate of peripherals is usually slower than the transfer rate of the CPU, and consequently, a synchronization mechanism may be needed
Explain this in simple words
IO interfacing involves creating a way for the microcontroller to communicate with external devices like sensors, displays, or other equipment. These devices work differently compared to the microcontroller's memory and processor, so a special communication link is needed to bridge the gap.
The main differences between the microcontroller and these peripherals are that the peripherals are made of moving parts and use different types of signals compared to the microcontroller. This means that sometimes the signal values need to be adjusted to match what the microcontroller can understand. Also, the transfer rate of the peripherals is usually slower than the microcontroller's, so a way to coordinate the timing of the data is necessary.
Programming Embedded Systems in C • Earlier, many embedded applications were developed using assembly level programming. However, they did not provide portability. • This disadvantage was overcome by the advent of various high-level languages like C, Pascal, and COBOL. • However, it was the C language that got extensive acceptance for embedded systems, and it continues to do so. • The C code written is more reliable, scalable, and portable; and in fact, much easier to understand. • Embedded C Programming is the soul of the processor functioning inside each and every embedded system we come across in our daily life, such as mobile phones, washing machines, and digital cameras. • Each processor is associated with embedded software. • The first and foremost thing is the embedded software that decides to function of the embedded system. • Embedded C language is most frequently used to program the microcontroller.
Explain this in understandabe words
In the past, embedded applications were commonly programmed using low-level assembly language, which was not very portable. However, high-level languages like C, Pascal, and COBOL helped to overcome this limitation. Among these languages, C gained widespread acceptance for embedded systems due to its reliability, scalability, and portability. Code written in C is easier to understand and work with.
Embedded C programming is fundamental to the operation of processors inside everyday embedded systems such as mobile phones, washing machines, and digital cameras. Each processor in these systems runs embedded software, which determines how the system functions. Embedded C is the most frequently used language for programming microcontrollers, making it essential for creating the software that controls these embedded devices.
C language was developed by Dennis Ritchie in 1969. • It is a collection of one or more functions, and every function is a collection of statements performing a specific task. • C language is a middle-level language as it supports highlevel applications and low-level applications. • The main features of the C language include the following. – C language is software designed with different keywords, data types, variables, constants, etc. – Embedded C is a generic term given to a programming language written in C, which is associated with a particular hardware architecture. – Embedded C is an extension to the C language with some additional header files. These header files may change from controller to controller. – The microcontroller 8051 #include<reg51.h> is used.
Explain in understandable words
The C language was created by Dennis Ritchie in 1969, and it is up of functions, which are groups of tasks, and statements that perform specific actions.
C is considered a "middle-level" language because it can be used to build both advanced applications and low-level system softwareSome key features of C include specific keywords, data types, variables, and constants. Embedded C refers to programming in C tailored to a particular hardware system. It's an extension of the C language and often involves additional header files that can vary depending the specific microcontroller being used, such as the 8051 which uses the header file 'reg51.h'.
What is an Embedded C Programming • In every embedded system based projects, Embedded C programming plays a key role to make the microcontroller run & perform the preferred actions. • At present, we normally utilize several electronic devices like mobile phones, washing machines, security systems, refrigerators, digital cameras, etc. • The controlling of these embedded devices can be done with the help of an embedded C program. • For example in a digital camera, if we press a camera button to capture a photo then the microcontroller will execute the required function to click the image as well as to store it.
Embedded C programming is essential for making microcontrollers operate and carry out specific tasks in embedded system projects. In our daily lives, we use various electronic devices, such as mobile phones, washing machines, security systems, refrigerators, and digital cameras. These devices are controlled using embedded C programs to perform their intended functions. For instance, in a digital camera, pressing the capture button triggers the microcontroller to execute the necessary tasks for taking and storing a photo.
What is an Embedded C Programming • In every embedded system based projects, Embedded C programming plays a key role to make the microcontroller run & perform the preferred actions. • At present, we normally utilize several electronic devices like mobile phones, washing machines, security systems, refrigerators, digital cameras, etc. • The controlling of these embedded devices can be done with the help of an embedded C program. • For example in a digital camera, if we press a camera button to capture a photo then the microcontroller will execute the required function to click the image as well as to store it. What is an Embedded C Programming • Embedded C programming builds with a set of functions where every function is a set of statements that are utilized to execute some particular tasks. • Both the embedded C and C languages are the same and implemented through some fundamental elements like a variable, character set, keywords, data types, declaration of variables, expressions, statements. • All these elements play a key role while writing an embedded C program. • The embedded system designers must know about the hardware architecture to write programs. • These programs play a prominent role in monitoring and controlling external devices. • They also directly operate and use the internal architecture of the microcontroller, such as interrupt handling, timers, serial communication, and other available features Embedded System Programming • The designing of an embedded system can be done using Hardware & Software. • For instance, in a simple embedded system, the processor is the main module that works like the heart of the system. • Here a processor is nothing but a microprocessor, DSP, microcontroller, CPLD & FPGA. • All these processors are programmable so that it defines the working of the device. Embedded System Programming • An Embedded system program allows the hardware to check the inputs & control outputs accordingly. • In this procedure, the embedded program may have to control the internal architecture of the processor directly like Timers, Interrupt Handling, I/O Ports, serial communications interface, etc. • So embedded system programming is very important to the processor. • There are different programming languages are available for embedded systems such as C, C++, assembly language, JAVA, JAVA script, visual basic, etc. • So this programming language plays a key role while making an embedded system but choosing the language is very essential.
Explain in simple and understandable words
Embedded C programming is crucial for making microcontrollers function in embedded projects. We use many electronic devices in our daily lives, such as mobile phones, washing machines, security systems, refrigerators, and digital cameras, and these devices rely on embedded C programs for their operations. For example, in a digital camera, when you press the capture button, the microcontroller executes the tasks to take and store a photo.
Embedded C programming consists of functions, each comprising specific statements to carry out designated tasks. embedded C and C languages share fundamental elements like variables, character sets, keywords, and data types, which are essential for writing embedded C programs. Understanding the hardware architecture is crucial for embedded system designers to create these programs, as they play a role in monitoring and controlling external devices. They also directly utilize the microcontroller's internal architecture, including interrupt handling, timers serial communication, and other available features.
When designing an embedded system, both hardware and software play important roles The processor, which can be a microprocessor, DSP, microcontroller, CPLD, or FPGA, serves as the central module. processors are programmable and determine how the device operates.
Embedded system programs enable the hardware to monitor inputs and control outputs. This often involves direct control of the processor's internal architecture, such as timers, interrupt handling, I/O ports, and serial communication interfaces. Therefore, embedded system programming is crucial for the processor's functioning. Different programming languages are available for embedded, including C, C++, assembly language, JAVA, JavaScript, and visual basic, and choosing the appropriate language is essential when creating an embedded system.
Steps to Build an Embedded C Program • Directives of Processor – The lines included within the program code are called preprocessor directives which can be followed through a hash symbol (#). – These lines are the preprocessor directives but not programmed statements. – The code can be examined through a preprocessor before real code compilation starts & resolves these directives before generating a code through regular statements. – There are several special preprocessor directives are available although two directives are extremely helpful within the programming language like the following. #include #include<reg51.h> Sbit LED = P2^3; Main(); { LED = 0x0ff Delay(); LED=0x00; } #define #include<reg51.h> #define LED P0 Main(); { LED = 0x0ff Delay(); LED=0x00; } – In the above program, the #include directive is generally used to comprise standard libraries like study and. h is used to allow I/O functions using the library of ‘C’. – The #define directive usually used to describe the series of variables & allocates the values by executing the process within a particular instruction like macros.
To build an Embedded C program, the following steps are typically involved:
Example:
#include <reg51.h> sbit LED = P2^3; void main() { LED = 0xff; delay(); LED = 0x00; }
In the given program, the #include directive is used to include standard libraries, and #define is used to assign the value.
It's worth noting that the actual implementation and the specifics of these steps can vary depending on the context and the specific requirements of the embedded system being developed.
Configuration of Port – The microcontroller includes several ports where every port has different pins. – These pins can be used for controlling the interfacing devices. – The declaration of these pins can be done within a program with the help of keywords. – The keywords in the embedded c program are standard as well as predefined like a bit, sbit, SFR which are used to state the bits & single pin within a program. – There are certain words that are reserved for doing specific tasks. – These words are known as keywords. – They are standard and predefined in the Embedded C. – Keywords are always written in lowercase. – These keywords must be defined before writing the main program. – The main functions of the keywords include the following. #include< > Sbit a = P 2^2; SFR 0x00 = PoRT0; Bit C; main() { …………….. …………….. }
The configuration of ports in a microcontroller involves assigning different pins the embedded C program to control interfacing devices. This is achieved using keywords that are both standard and predefined, such as 'bit', 'sbit', and 'SFR', which are used to indicate bits and single pins within the program.
Keywords in embedded C are reserved words that serve specific functions. They must be defined before writing the main program and are always written in lowercase. For example:
#include<reg51.h> s a = P2^2; sfr P0 = 0x00; C; void main() { // Main program code goes here }
In the given example, we see the usage of keywords to define the port configuration and other related. It's essential to properly understand and use these keywords to effectively configure and operate the microcontroller's ports within embedded C program.
sbit – This is one kind of data type, used to access a single bit within an SFR register. – The syntax for this data type is : sbit variable name = SFR bit ; • Example: sbit a=P2^1; – If we assign p2.1 as ‘a’ variable, then we can use ‘a’ instead of p2.1 anywhere in the program, which reduces the complexity of the program. • Bit – This type of data type is mainly used for allowing the bit addressable memory of random access memory like 20h to 2fh. – The syntax of this data type is : name of bit variable; • Example: bit c; – It is a bit series setting within a small data region that is mainly used with the help of a program to memorize something. • SFR – This kind of data type is used to obtain the peripheral ports of the SFR register through an additional name. – So, the declaration of all the SFR registers can be done in capital letters. – The syntax of this data type is: SFR variable name = SFR address for SFR register; • Example: SFR port0 = 0×80; – If we allocate 0×80 like ‘port0’, after that we can utilize 0×80 in place of port0 wherever in the programming language to decrease the difficulty of the program. • SFR Register – The SFR stands for Special Function Register. – In 8051 microcontroller, it includes the RAM memory with 256 bytes, which is divided into two main elements: – the first element of 128 bytes is mainly utilized for storing the data whereas the other element of 128 bytes is mainly utilized to SFR registers. – All the peripheral devices such as timers, counters & I/O ports are stored within the SFR register & every element includes a single address.
Explain this in simple words
Certainly! Here's a simpler explanation for the terms mentioned:
sbit: This is used to access a single bit within a special function register (SFR). It allows us to assign a name to a specific bit, making the program easier to understand and work with.
Example: If we assign the bit P2.1 as 'a', we can use 'a' instead of P2.1 in the program, reducing complexity.
Bit: This data type allows us to use bit-addressable memory in the range of 20h to 2fh in the microcontroller's memory. It is used to store individual bits of data within a small data region.
Example: Declaring a bit variable 'c' allows us to store and work with a single bit of information in the program.
SFR: This data type is used to access peripheral ports of the SFR register using a different name. It allows us to declare SFR registers with a specific name.
Example: By assigning 0x80 to 'port0', we can use 'port0' instead of 0x80 in the program, making it easier to manage.
SFR Register: Special Function Register is a part of the microcontroller's RAM memory. In the 8051 microcontroller, it includes 256 bytes, with 128 bytes used for data storage and the other 128 bytes used for SFR registers. These registers store information about peripheral devices like timers, counters, and I/O ports, each having a unique address.
Steps to Build an Embedded C Program • The logic of the Program – The logic of the program is a plan of the lane that appears in the theory behind & predictable outputs of actions of the program. – It explains the statement otherwise theory regarding why the embedded program will work and shows the recognized effects of actions otherwise resources. Main { LED = 0x0f; delay(100); LED = 0x00; delay(100); }
Certainly! Here are the steps to build an Embedded C program based on the provided logic:
Elaborate the Program Logic:
Write the Code:
main() { LED = 0x0F // Turn on the LED delay(100); // Delay for 100 LED = 0x00; // Turn off LED delay(100); // Delay for another 100 milliseconds }
Define External Functions - If the 'delay()' function is not already defined, it needs be created or included from a library. The 'delay()' function is essential for creating time delays in the program.
Configure the Microcontroller:
Compile and Load - Compile the program code using a C compiler compatible with the target microcontroller. After successful, load the compiled code onto the microcontroller for execution.
Following these steps will help create an Embedded C program based on the provided logic, enabling the microcontroller to control the LED as intended.
difference between IOT and M2M with tabular column with brief explanations
Certainly! Here's a comparison between IoT (Internet of Things) and M2M (Machine to Machine) with a tabular column and brief explanations:
| Aspect | IoT | M2M |
|---|---|---|
| Definition | IoT refers to a network of interconnected | M2M involves communication between |
| physical devices, vehicles, appliances, | devices or machines without human intervention | |
| and more, enabling them to exchange data, | for automated data exchange and actions. | |
| analyze and adapt to their environments. | ||
| Purpose | Focuses on enabling interconnect and | Primarily targets automated communication |
| data sharing between diverse devices and | and interaction between specific machines or | |
| systems to facilitate smart and adaptive | devices for specific operational objectives. | |
| functionalities. | ||
| Scope | Encompasses a wider range of applications, | Typically applied to specific use cases such |
| including smart cities, healthcare, | as industrial automation, fleet management, | |
| agriculture, and consumer electronics. | and remote monitoring, with a narrower focus. | |
| Communication | IoT devices often utilize internet | M2M communication occurs via various |
| Medium | connectivity (Wi-Fi, cellular networks, | communication protocols such as cellular |
| Bluetooth, etc.) to facilitate data | networks, Zigbee, Bluetooth, and dedicated | |
| transfer and remote control. | M2M technologies. | |
| Human Interaction | Involves human-device but also | Primarily focuses on direct device-to-device |
| encompasses automated machine-to- | communication with minimal human | |
| machine and machine-to communication. | intervention. |
In summary, while IoT represents a broader ecosystem of connected with a focus on diverse applications and adaptive functionalities, M2M is more narrowly focused on direct machine-to-machine communication for specific operational objectives. Both concepts play crucial roles in enabling automation, data exchange, and smart capabilities.
IoT communication APIs These APIs like REST and WebSocket are used to communicate between the server and system in IoT.
REST-based communication APIs Representational state transfer(REST) API uses a set of architectural principles that are used to design web services. these APIs focus on the systems’ resources that how resource states are transferred using the request-response communication model. This API uses some architectural constraints.
Client-server Here the client is not aware of the storage of data because it is concerned about the server and similarly the server should not be concerned about the user interface because it is a concern of the client. and this separation is needed for independent development and updating of the server and client. no matter how the client is using the response of the server and no matter how the server is using the request of the client.
Stateless It means each request from the client to the server must contain all the necessary information to understand the server. because if the server can’t understand the request of the client then it can’t fetch the requested data in a proper manner.
Cacheable In response, if the cache constraints are given then a client can reuse that response in a later request. it improves the efficiency and scalability of the system without loading extra data
Explain in simple words
Sure, let's simplify the concept of REST-based communication APIs for IoT in simple words:
REST (Representational State Transfer) API is like a set of rules for how computers can talk to each other over the internet. It's used to help systems like IoT devices and servers communicate.
Here's what it means in simple terms:
Client-Server: Imagine there's a chef and a waiter in a restaurant. The chef just focuses on cooking the food (server) and the waiter just focuses on serving the food to the customers (client). They don't need to know all the details about each other's jobs to work well together.
Stateless: When a customer orders food at a restaurant, they tell the waiter everything they need right then and there. They don't assume the waiter knows what they want based on a previous visit. The same goes for computers talking to each other - each request has all the information needed to understand it.
Cacheable: Imagine if the restaurant keeps a record of popular food orders. The next time someone orders the same food, the waiter can just bring it out quickly. Computers can do something similar, where they save and reuse responses to make things faster without needing to ask the server again.
So, in simple terms, REST APIs are like a set of rules that help computers (like IoT devices and servers) talk to each other efficiently and work together smoothly, just like a well-organized restaurant with chefs and waiters.
WebSocket-based communication API This type of API allows bi-directional full-duplex communication between server and client using the exclusive pair communication model. This API uses full-duplex communication so it does not require a new connection setup every time when it requests new data. WebSocket API begins with a connection setup between the server and client and if the WebSocket is supported by the server then it responds back to the client with a successful response after the setup of a connection server and the client can send data to each other in full-duplex mode.
this type of API reduces the traffic and latency of data and makes sure that each time when we request new data it cannot terminate the request.
Explain in simple words
Certainly! WebSocket-based communication API is like a special phone line that allows instant back-and-forth talking between two parties (like a server and a client) on the internet. It's different from a regular phone call because both sides can speak and listen at the same time.
Here's a simple way to understand it:
Imagine you're talking to a friend on a special phone line. With this special line, you don't need to say "hello" and "goodbye" every time you want to share something new. Once the line is set up, you can both talk and listen freely without needing to start over each time.
In the same way, the WebSocket API sets up a direct line of communication between the server and the client. Once this line is established, they can send data back and forth to each other without having to keep setting up the connection again and again. This makes things quicker and more efficient because they can keep the line open and just send data back and forth whenever they need to, without any interruptions.
So, in simple terms, the WebSocket API is like a special phone line that allows instant and smooth two-way communication without any need for constant reconnections.
#include <Servo.h> //Including the servo library for the program int servoPin = 12; Servo ServoDemo; // Creating a servo object void setup() { // The servo pin must be attached to the servo before it can be used ServoDemo.attach(servoPin); } void loop(){ //Servo moves to 0 degrees ServoDemo.write(0); delay(1000); // Servo moves to 90 degrees ServoDemo.write(90); delay(1000); // Servo moves to 180 degrees ServoDemo.write(180); delay(1000); } Explain in just the simple words
This Arduino code uses a servo motor to move to three different positions: 0 degrees, 90 degrees, and 180 degrees.
The "servoPin" is connected to the servo motor, and the program uses the Servo library to control the motor. In the setup, the program attaches the servo pin to the ServoDemo object.
In the loop, the code commands the servo to move to 0 degrees, then 90 degrees, then 180 degrees, with a one-second delay between each movement.
In simpler terms, the code makes the servo motor move to three specific angles in a sequence.
As the IoT platform model is attracting a larger following and is carving its way into large industrial corporations, building open-source IoT platforms is a logical step towards making the IoT platform movement available to as many users and contributors as possible
Explain this in simple words
This statement is saying that as more people are getting interested in using IoT platforms, especially in big companies, creating open-source (free and accessible) IoT platforms is a good idea. This way, more people can use and contribute to the development of these platforms, making them available to a wider audience.
OpenRemote is a 100% free open source IoT platform. The user-friendly interface makes it possible for companies and individuals to integrate and manage their assets within one central location, design applications and workflows, and visualize data in dashboards. The platform also supports an array of data processing tools.
OpenRemote is a completely free IoT platform that anyone can use. Its easy-to-use interface allows both companies and individuals to bring together and control their devices in one place, create applications and workflows, and see their data in visual dashboards. It provides various tools for working with data.
key capabilities of OpenRemote "integration of different asset types support of standard protocols such as HTTP or MQTT as well as specific protocols like KNX for connecting IoT devices a customizable manager interface for the automation, monitoring, and control of processes, apps, and devices a mobile app so that you can connect to your phone services and push notifications Multi-tenancy with user roles and a full account management service."
Explain this in simple words
OpenRemote has several important features:
THINGSBOARD:
ThingsBoard is an open-source IoT platform for the collection processing, analysis, and visualization of data. The platform also comes with a device management service and users can connect their devices using any standard protocol such as HTTP, MQTT, or CoAP. With ThingsBoard, users can build and manage their own workflows.
ThingsBoard is an open-source IoT platform that helps gather, process, analyze, and display data. It includes a service for managing, and supports connecting devices using standard protocols like HTTP, MQTT, or CoAP. With ThingsBoard, users can and control their own workflows.
IoT device management with monitoring and control mechanisms scalability with the capability to orchestrate multiple devices at the same time, across the entire IoT ecosystem enables users to create and manage alerts for connected devices (e.g. in the event of a disconnect or inactivity), other assets, and customers with real-time alarm monitoring. extending default functionality with customizable rule chains, widgets, and transport implementations multi-tenancy
This description outlines the key features of an IoT platform:
Thinger.io is a scalable IoT cloud platform for connecting devices. An easy-to-navigate ready-to-use cloud infrastructure that allows users to integrate, monitor, and control millions of IoT devices. The platform creators believe in the importance of a great developer experience. In their own words, the platform is “easy to use, and easy to understand. No more complex code for doing simple things.” The platform is hardware-agnostic. Connect any device, the most typical being Arduino, ESP8266, Raspberry Pi, and Intel Edison. Simply install the server in your own cloud and use the open-source libraries for integrating the IoT devices.
Thinger.io is an IoT cloud platform that can handle a large number of devices. It offers a user-friendly cloud system for integrating, monitoring, and controlling millions of IoT devices. The platform focuses on providing a great experience for developers, aiming to be easy to use and understand, eliminating the need for complex code to accomplish simple tasks. It is compatible with various hardware, such as Arduino, ESP8266, Raspberry Pi, and Intel Edison. Users can install the server in their own cloud and utilize open-source libraries to integrate their IoT devices.
This is an open-source IoT platform that focuses on edge computing. Mainflux is patent-free and end-to-end, under an Apache 2.0 license, and covering most of the things needed for developing IoT solutions, applications, and products. Users can benefit from the platform’s full transparency, full user control over their own assets, as well as the possibility to do community testing, support, and bug fixes. As the platform was built as a set of containerized microservices orchestrated by Kubernetes, there is no vendor lock-in. Mainflux provides the complete infrastructure and middleware to execute: Device management Data aggregation & data management Connectivity & message routing IoT application enablement Analytics
Mainflux is an open-source IoT platform that emphasizes edge computing. It is patent-free and provides end-to-end functionality under an Apache 2.0 license, covering most components essential for developing IoT solutions, applications, and products. The platform offers full transparency, granting users control over their assets and the opportunity for community testing, support, and bug fixes. Mainflux's design as a set of containerized microservices orchestrated by Kubernetes eliminates vendor lock-in. It encompasses the infrastructure and middleware for device management, data aggregation and management, connectivity and message routing, IoT application enablement, and analytics.