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Surajkumar Sharma


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Serial Interrupt Programming in 8051 Microcontroller

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Serial Interrupt Programming in 8051 Microcontroller Baud Rate calculation: To meet the standard baud rates generally crystal with 11.0592 MHz is used. As we know, 8051 divides crystal frequency by 12 to get a machine cycle frequency of 921.6 kHz. The internal UART block of 8051 divides this machine cycle frequency by 32, which gives the frequency of 28800 Hz which is used by UART. To achieve a baud rate of 9600, again 28800 Hz frequency should be divided by 3. This is achieved by using Timer1 in mode-2 (auto-reload mode) by putting 253 in TH1 (8-bit reg.) So 28800 Hz will get divided by 3 as the timer will overflow after every 3 cycles. we can achieve different baud rates by putting the division factor in the TH1 register. Division factor to achieve different baud rates Baud Rate TH1 (Hex) 9600 FD 4800 FA 2400 F4 1200 E8 SCON: Serial Control Register      Serial control register SCON is used to set serial communication operation modes. Also, it is used to control transmi...
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LCD Interfacing with 8051 Microcontroller

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LCD Interfacing with 8051 Microcontroller Hex Code Command to LCD Instruction Register 0F LCD ON, cursor ON 01 Clear display screen 02 Return home 04 Decrement cursor (shift cursor to left) 06 Increment cursor (shift cursor to right) 05 Shift display right 07 Shift display left 0E Display ON, cursor blinking 80 Force cursor to the beginning of the first line C0 Force cursor to the beginning of the second line 38 2 lines and 5×7 matrix 83 Cursor line 1 position 3 3C Activate the second line 08 Display OFF, cursor OFF C1 Jump to the second line, position 1 OC Display ON, cursor OFF C1 Jump to the second line, position 1 C2 Jump to a second line, position 2 Circuit Diagram : Source Code: // Program for LCD Interfacing with 8051 Microcontroller (P89V51RD2) #include<reg51.h> #include <string.h> #define display_port P2 //Data pins connected to port 2 on microcontroller sbit rs = P0^0; //Register Select pin connected to pin 0 of port 0 sbit rw = P0^1; // Read/Write p...
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Interfacing LED with 8051 Microcontroller in Assembly

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Blinking 1 LED using 8051 This is the first project regarding 8051 and of course one of the simplest, blinking LEDs using 8051. The microcontroller used here is AT89S51 In the circuit, push-button switch S1, capacitor C3 and resistor R3 form the reset circuitry. When S1 is pressed, the voltage at the reset pin (pin9) goes high and this resets the chip. C1, C2, and X1 are related to the on-chip oscillator which produces the required clock frequency. P1.0 (pin1) is selected as the output pin. When P1.o goes high the transistor Q1 is forward biased and LED goes ON. When P1.0 goes low the transistor goes to cut off and the LED extinguishes. The transistor driver circuit for the LED can be avoided and the LED can be connected directly to the P1.0 pin with a series current limiting resistor(~1K).  The time for which P1.o goes high and low (the time period of the LED)  is determined by the program. The circuit diagram for blinking 1 LED is shown below. Program. START: CPL P1.0 ...
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