At89c2051 | Projects

Timer interrupts, random number generation, button debouncing. Project 4: Frequency Counter (0-50 kHz) Difficulty: Advanced Components: External TTL signal source, LCD 16x2 (optional via 4-bit mode)

This project demonstrates a security system. The user must enter a 4-digit code; if correct, a relay is energized to open a lock. Rows to P3.0-P3.3 (outputs), Columns to P1.0-P1.3 (inputs with pull-ups). Scan the keypad using the classic row-scan method. Code logic: unsigned char code[4] = 1,2,3,4; // correct code unsigned char entered[4]; unsigned char pos = 0; void main() while(1) unsigned char key = get_key(); if(key != 0xFF) entered[pos++] = key; beep(); if(pos == 4) if(memcmp(entered, code, 4) == 0) relay_on(); delay_ms(3000); relay_off(); else // wrong code: beep error at89c2051 projects

This project verifies your hardware and programmer work. Connect an LED with a 220Ω series resistor between P1.0 and GND. Code (C for SDCC/Keil): #include <at89x051.h> #include <delay.h> // simple delay function void delay_ms(unsigned int ms) unsigned int i, j; for(i = 0; i < ms; i++) for(j = 0; j < 1275; j++); Rows to P3

Servos require a 50Hz PWM signal with pulse widths from 1ms to 2ms. Connect an LED with a 220Ω series resistor between P1

void main() // Configure Timer0 in mode 1 TMOD

Timer/counter modes, frequency measurement techniques. Project 5: Simple Servo Motor Controller Difficulty: Intermediate Components: SG90 or MG995 servo, 5V supply, potentiometer (10k)

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Timer interrupts, random number generation, button debouncing. Project 4: Frequency Counter (0-50 kHz) Difficulty: Advanced Components: External TTL signal source, LCD 16x2 (optional via 4-bit mode)

This project demonstrates a security system. The user must enter a 4-digit code; if correct, a relay is energized to open a lock. Rows to P3.0-P3.3 (outputs), Columns to P1.0-P1.3 (inputs with pull-ups). Scan the keypad using the classic row-scan method. Code logic: unsigned char code[4] = 1,2,3,4; // correct code unsigned char entered[4]; unsigned char pos = 0; void main() while(1) unsigned char key = get_key(); if(key != 0xFF) entered[pos++] = key; beep(); if(pos == 4) if(memcmp(entered, code, 4) == 0) relay_on(); delay_ms(3000); relay_off(); else // wrong code: beep error

This project verifies your hardware and programmer work. Connect an LED with a 220Ω series resistor between P1.0 and GND. Code (C for SDCC/Keil): #include <at89x051.h> #include <delay.h> // simple delay function void delay_ms(unsigned int ms) unsigned int i, j; for(i = 0; i < ms; i++) for(j = 0; j < 1275; j++);

Servos require a 50Hz PWM signal with pulse widths from 1ms to 2ms.

void main() // Configure Timer0 in mode 1 TMOD

Timer/counter modes, frequency measurement techniques. Project 5: Simple Servo Motor Controller Difficulty: Intermediate Components: SG90 or MG995 servo, 5V supply, potentiometer (10k)