4 February, 2012

Registers in 8051 microcontroller

In the CPU, registers are used to store information temporarily. That information could be a byte of data to be processed, or an address pointing to the data to be fetched. The vast majority of 8051 registers are 8-bit registers. In the 8051 there is only one data type: 8-bits. With an 8-bit data type, any data larger than 8-bits must be broken into 8-bit chunks before it is processed.Read More

2 February, 2012

Program counter in 8051

Another important register in the 8051 is the PC (program counter). The program counter points to the address of the next instruction to be executed. As the CPU fetches the opcode from the program ROM, the program counter is incremented to point to the next instruction. The program counter in the 8051 is 16-bits wide. Read More

4 February, 2012

Stacks in the 8051

Stacks in the 8051: The stack is a section of RAM used by the CPU to store the information temporarily. This information could be data or address. CPU needs this storage area since there are only a limited number of registers. If the stack is a section of RAM, there must be registers inside the CPU to point to it. Read More

2 February, 2012

PSW Register of 8051

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 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.Read More

2 February, 2012

Register banks in 8051

A total of 32 bytes of RAM are set aside for the register banks and stack. These 32 bytes are divided into 4 banks of registers in which each bank has 8 registers, R0-R7 where R0 is RAM location 0; R1 is RAM location 1, and so on, until memory location 7, which belongs to R7 of bank 0.The second bank of registers R0-R7 starts at RAM location 08 and goes to location 0FH. Read More

5 February, 2012

Why program the 8051 in C

Compilers produce hex file that is downloaded to ROM of microcontroller. The size of hex file is the main concerns of microcontroller programmers.C programming is less time consuming and much easier to write, but has larger hex file size produced is much larger than if we used assembly language.The following are some of the major reasons for writing programs in C instead of assembly.Read More

5 February, 2012

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