185 lines
3.9 KiB
C
185 lines
3.9 KiB
C
#include <stdlib.h>
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include <avr/pgmspace.h>
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#include <util/delay.h>
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#include <string.h>
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#include "utils.h"
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#include "main.h"
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#include "uart.h"
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#define POWER_MIN 0
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#define POWER_MAX 400
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#define SERVO_STEPS 125
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#define BUFSIZE 10
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volatile uint16_t syscounter = 0;
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volatile uint16_t power;
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uint8_t data_count = 0;
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char data_in[BUFSIZE];
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void reset_input_buffer(void) {
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data_count = 0;
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memset(data_in, 0, BUFSIZE);
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}
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static void timer_init(void) {
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// CTC Mode for Timer 1 (16Bit) with prescale of 64
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TCCR1B |= _BV(WGM12) | _BV(CS11) | _BV(CS10);
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OCR1A = 2250; // set Servo to max. position
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TIMSK |= _BV(OCIE1A); // enable timer interrupt
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TCCR1A |= _BV(COM1A0); // toggle OCR1A on overflow
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// CTC Mode for Timer 0 (8Bit) with prescale of 1024
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TCCR0B |= _BV(CS02) | _BV(CS00); // prescaler
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TCCR0A |= _BV(WGM01); // CTC mode
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TIMSK |= _BV(OCIE0A); // enable timer interrupt
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OCR0A = 78; // gives us ~100ms interval
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}
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static void ports_init(void) {
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DDRB |= _BV(PB3);
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}
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static void work_uart() {
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uint16_t c = uart_getc();
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if ( !(c & UART_NO_DATA) ) {
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char cur = c & 0xff;
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data_in[data_count] = cur;
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//uart_print_uint8(cur);
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data_count++;
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if(data_count >= BUFSIZE) { // buffer overflow
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reset_input_buffer();
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}
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#ifdef DEBUG1
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for(uint8_t i=0;i<BUFSIZE;i++) {
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uart_print_uint8(data_in[i]);
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uart_putc('\r');
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uart_putc('\n');
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}
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uart_puts_P(" -- \r\n");
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#endif
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if (cur == 13) { // \n
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power = atol(data_in);
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if(power > POWER_MAX) power = POWER_MAX;
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#ifdef DEBUG
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uart_puts_P("power = ");
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uart_print_uint16(power);
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uart_puts_P("\r\n");
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#endif
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if(power > 0) {
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set_servo(power);
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}
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reset_input_buffer();
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}
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}
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}
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/**
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* \brief set the servo to a position calculated to given power
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*
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* \param display The power value from 0 to 400 (including bounds)
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*/
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void set_servo(uint16_t display) {
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if( display > POWER_MAX ) display = POWER_MAX;
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display = POWER_MAX-display; // invert the value / servo
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display = display * 10; // *10 otherwise we need float
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display = display / ((POWER_MAX * 10) / SERVO_STEPS);
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display = display + SERVO_STEPS;
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#ifdef DEBUG
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uart_puts_P("display = ");
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uart_print_uint16(display);
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uart_puts_P("\r\n");
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#endif
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if( display < 125 ) display = 125; // just make sure, the timer
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if( display > 250 ) display = 250; // is never out ouf 20ms grid
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// check if timer is currently in the small pulse, then sleep here 2ms
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// and do again
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if(OCR1A <= 2250) {
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_delay_ms(10);
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}
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//cli(); // read and write atomic
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TIMSK &= ~(_BV(OCIE1A));
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OCR1A = 2500-display;
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//sei();
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TIMSK |= _BV(OCIE1A);
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}
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/**
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* \brief the method moves the servo one complete cycle
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*/
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static void demo_display(void) {
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set_servo(0);
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wait(100);
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set_servo(400);
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wait(100);
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set_servo(0);
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wait(100);
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}
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int main(void) {
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sei();
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ports_init();
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timer_init();
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uart_init(UART_BAUD_SELECT(38400,F_CPU));
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reset_input_buffer();
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//demo_display();
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while(1) {
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work_uart();
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if(syscounter >= 10) {
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reset_input_buffer();
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uart_putc('a'); // send a to receive values from master box
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syscounter = 0;
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#ifdef DEBUG
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uart_puts_P("OCR1A = ");
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uart_print_uint16(OCR1A);
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uart_puts_P("\r\n");
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#endif
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}
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}
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return(0);
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}
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/**
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* \brief this is our timer for PWM generation and system clock
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* the system clock varies a bit, but this does not matter
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*/
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ISR(TIMER1_COMPA_vect) {
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OCR1A = 2500-OCR1A; // Das Servosignal wird aus der Differenz von
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// Periodenlänge (2500*0,008ms=20ms) und letztem
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// Vergleichswert (OCR1A) gebildet
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}
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ISR(TIMER0_COMPA_vect) {
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syscounter++;
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}
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