8051: Unique Features

The 8051 microcontroller is generic part number actually includes a whole family of microcontrollers that have numbers ranging from 8031 to 8751 and are available in N-channel Metal Oxide Silicon(NMOS) and Complimentary Metal Oxide Silicon(CMOS) constructed in a variety of package types. The unique features of 8051 are;

♂Internal RAM and ROM
♂I/O ports with programmable pins
♂Timers and counters
♂Serial data communication
The block diagram shows usual CPU components- program counter, ALU, working registers, and clock circuits.
The 8051 architecture consists of these specific features;
●8-bit CPU registers A(the accumulator) and B
●16-bit program counter(PC)and data pointer(DPTR)
●8-bit status word
●Internal ROM or EPROM(for 8751) of 0(for 8031) to 4K(for 8051)
●Internal RAM of 128 bytes:
◆Four register banks each containing 8 registers
◆16-bytes, which may be addressed at the level
◆80-bytes general purpose data memory
◆32 I/O pins arranged as 4 eight-bit ports:P0 to P3
◆Two 16-bit timer/counters: T0 and T1
◆Full duplex serial data receiver/transmitter
◆Control registers: TCON, TMOD, SCON, IP and IE
◆Two external and 3 internal interrupt sources
◆ Oscillator and clock circuits

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8051 Simple Programs

Sum of 8-bit Numbers Stored in Memory Here we will discuss about 8051 programs but we can't discuss about all of the 8051 instructions. For programming 8051 we should know about assembler directives as well as instruction set. Click here to download Atmel c51 user guide that will discuss about 8051(c51 family microcontroller) instruction set, assembler directives, c51 cross assembler from Atmel. Program ORG 00H MOV R0,#50H ; get memory location in memory pointer R0 MOV R1,#51H ; get memory location on memory pointer register R1 MOV A,@R0 ; get content of memory location 50H to accumulator ADD A,@R1 ; add content of A with content of memory location 51H and store result in A MOV R0,#52H ; get 52H to memory pointer R0 MOV@R0,A ; copy content of A to memory location 52H END Add 16-bit Numbers ...

Introduction to 8051 embedded C

For 8051 we need to include the file reg51.h. This file contains the all the definitions of 8051 registers. With this information C compiler produces hex file that can be downloaded into the ROM of the microcontroller. It is important to note that the size of the hex file produced by the assembly language is much larger than the hex file produced by C compiler. Apart from this fact, there is many reasons for writing programs in C instead of assembly: ●It is much easier and less time consuming to write programs in C assembly. ●C is more flexible; it is easier to modify and update. ●Programming in C allows to use code available in function libraries. ●Program written inC for one microcontroller is portable to other microcontrollers with little or no modifications. Data Types in 8051 Embedded C The table shown below lists the data types that are available in typical C51 compiler. The gives information about the size of the data variable and it's value range. Data type ...

Frequency of Oscillation of RC Phase Shift Oscillator

Derivation of Frequency of Oscillation We have to find out the transfer function of RC feedback network. Feedback Circuit of RC Phase Shift Oscillator Applying KVL to various loops on the figure, we get, $$I_1 \left(R+\frac{1}{j \omega C }\right) -I_2R=V_i \text{ ....(1)}$$ $$-I_1R+I_2\left (2R+\frac {1}{j\omega C}\right)-I_3R=0\text{ ... (2)}$$ $$0-I_2R+I_3\left(2R+ \frac{1}{j\omega C}\right)=0\text{ ...(3)}$$ Replacing $j\omega$ with $s$ and writing equations in the matrix form, $$\begin{bmatrix}R+\frac{1}{sC} & -R & 0 \\-R & 2R+\frac{1}{sC} & -R \\0 & -R & 2R+\frac{1}{2sC} \end{bmatrix}\begin{bmatrix}I_1\\I_2\\I_3\end{bmatrix}=\begin{bmatrix}V_i\\0\\0\end{bmatrix}$$ Using Cramer's rule to find out $I_3$, $$\text{Let, }D=\begin{bmatrix}R+\frac{1}{sC} & -R & 0 \\-R & 2R+\frac{1}{sC} & -R \\0 & -R & 2R+\frac{1}{2sC} \end{bmatrix}$$ \(|D|=\begin{vmatrix}R+\frac{1}{sC} & -R & 0 \\-R & 2R+\frac{1}{...

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