| 0,0 → 1,103 |
|---|
| // timer_demo1.c |
| // ------------- |
| // |
| // Example file for ATmega88 (and similar AVR chips) demonstrating how to use |
| // timer interrupt just to blink by LED. |
| // |
| // The program uses TIMER1 to generate interrupts and the interrupt routine |
| // toogles the LED state. Connect LED to ground with apropriate serial resistor |
| // (value about 330 OHM). |
| // |
| // (c) miho 2014 http://www.mlab.cz |
| // |
| // History |
| // 2014 01 29 - First demo |
| |
| |
| // System Configuration |
| #define F_CPU 4000000 // Do not forget to set FUSEs to external XTAL osc with DIV/8 off and connect xtal |
| |
| |
| // LED Ports Configuration |
| #define LED_S_PORT C |
| #define LED_S_PIN 4 |
| #define LED_M_PORT C |
| #define LED_M_PIN 5 |
| |
| |
| // -------------- DO NOT EDIT BELOW THIS LINE -------------- |
| |
| |
| // Library Headers |
| #include <avr/interrupt.h> |
| |
| |
| // Comaptibility ATmega8 / ATmega88 |
| #ifndef TIMSK |
| #define TIMSK TIMSK1 |
| #endif |
| |
| |
| // Macro for Port (enables to easily define IO signals) |
| #define GLUE(A,B) A##B |
| #define DDR(PORT_LETTER) GLUE(DDR, PORT_LETTER) // Makes DDRC from DDR(C) |
| #define PORT(PORT_LETTER) GLUE(PORT,PORT_LETTER) // Makes PORTC from PORT(C) |
| #define PIN(PORT_LETTER) GLUE(PIN, PORT_LETTER) // Makes PINC from PIN(C) |
| |
| |
| // Global Variable |
| volatile int Seconds; |
| |
| // Interrupt Routine for TIMER1 Output Compare A |
| ISR(TIMER1_COMPA_vect) |
| { |
| // LED on/off |
| PORT(LED_S_PORT) ^= (1<<LED_S_PIN); |
| if (Seconds<59) |
| { |
| Seconds++; |
| } |
| else |
| { |
| Seconds=0; |
| // Toogle Minute LED |
| PORT(LED_M_PORT) ^= (1<<LED_M_PIN); |
| } |
| } |
| |
| |
| // Main |
| int main() |
| { |
| // Enable LED Output |
| DDR(LED_S_PORT) |= (1<<LED_S_PIN); |
| DDR(LED_M_PORT) |= (1<<LED_M_PIN); |
| |
| // Set MAX value for Timer1 |
| OCR1A = F_CPU/256/2-1; // 1/2s |
| |
| // Set Timer1 to CTC with presacaller 1/256 |
| // CTC Mmode counts from 0 to value stored in OCR1A |
| // and generates interrupt every time it goes back to 0 |
| // CS12 CS11 CS10 Prescaller |
| // 0 0 1 clkI/O/1 (No prescaling) |
| // 0 1 0 clkI/O/8 (From prescaler) |
| // 0 1 1 clkI/O/64 (From prescaler) |
| // 1 0 0 clkI/O/256 (From prescaler) |
| // 1 0 1 clkI/O/1024 (From prescaler) |
| TCCR1B |= (1<<CS12) | (1<<WGM12); |
| |
| // Enable Interrupt for Timer1 OCRA |
| TIMSK |= (1<<OCIE1A); |
| |
| // Enable Global (CPU) Interrupt |
| sei(); |
| |
| // Main Loop |
| for(;;) |
| { |
| // Do any job here |
| } |
| |
| return 0; |
| } |