bikegenerator/schaltungen/displayboard_servo/software/src/main.c

#include <stdlib.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include <string.h>
#include "utils.h"
#include "main.h"
#include "uart.h"

#define POWER_MIN	0
#define POWER_MAX	400
#define SERVO_STEPS	125

#define BUFSIZE		32

volatile uint16_t syscounter = 0;

// values send over uart from powerboard
typedef struct {
	uint16_t voltage_gen;
	uint16_t voltage_reg;
	uint16_t current_gen;
	
	struct {
		uint8_t loadsw : 1;
		uint8_t gensw : 1;
		uint8_t batsw : 1;
	};
} PWR_DATA;

static PWR_DATA pd;
uint8_t data_count = 0;
char data_in[BUFSIZE];
   
void reset_input_buffer(void) {
	data_count = 0;
	memset(data_in, 0, BUFSIZE);
}

static void update_servo_position() {
	uint32_t power;
	power = ( (pd.voltage_gen / 100) * (pd.current_gen / 100) ) / 100;      
	set_servo(power & 0xffff); 
}
   
static void timer_init(void) {
	// CTC Mode for Timer 1 (16Bit) with prescale of 64
	TCCR1B |= _BV(WGM12) | _BV(CS11) | _BV(CS10);       
	OCR1A = 2250;           // set Servo to max. position
	TIMSK |= _BV(OCIE1A);	// enable timer interrupt
	TCCR1A |= (1<<COM1A0);   // toggle OCR1A on overflow
}

static void ports_init(void) {
	DDRB |= _BV(PB3); 
}

static void process_command(char *command) {
	if(command[0] == 'A') {
		// command must be in the following format:
		// A$voltage_gen,$voltage_reg,$current_gen,loadsw,batsw,gensw\n
		// examples: 
		//	A24500,13400,12000,1,1,1B
		//	A19900,11000,15000,1,1,1B
		//	A20000,12300,10000,1,1,1B

		char *token;
		uint8_t tokencounter = 0;

		token = strtok(command, ","); 

		while( token ) {
			switch(tokencounter) {
				case 0:
					// skip the A in front of the number
					pd.voltage_gen = atoi(++token);
					break;
				case 1:
					pd.voltage_reg = atoi(token);
					break;
				case 2:
					pd.current_gen = atoi(token);
					break;
				case 3:
					if(atoi(token) == 1) pd.loadsw = 1;
					else pd.loadsw = 0;
					break;
				case 4:
					if(atoi(token) == 1) pd.batsw = 1;
					else pd.batsw = 0;
					break;
				case 5:
					if(atoi(token) == 1) pd.gensw = 1;
					else pd.gensw = 0;
					break;
			}
			
			tokencounter++;
			token = strtok(NULL, ",");
		}

		update_servo_position();        
	}
}

static void work_uart() {
	uint16_t c = uart_getc();

	if ( !(c & UART_NO_DATA) ) {
		data_in[data_count] = (c & 0xff);

		if (data_in[data_count] == 'B') {
			process_command(data_in);    
			reset_input_buffer();
		} 

		data_count++;
		if(data_count >= BUFSIZE) {	// buffer overflow
			reset_input_buffer();
		}
	}
}

/**
 *	\brief	set the servo to a position calculated to given power
 * 
 * 	\param	display 	The power value from 0 to 400 (including bounds)
 */
void set_servo(uint16_t display) {

	if( display < 1 ) display = POWER_MIN;
	if( display > POWER_MAX ) display = POWER_MAX;

	display = POWER_MAX-display;	  // invert the value / servo

	display = display * 10;				// *10 otherwise we need float
	display = display / ( (POWER_MAX*10) / SERVO_STEPS );
	display = display + SERVO_STEPS;

	uart_puts_P("display = ");
	uart_print_uint16(display);
	uart_puts_P("\r\n");

	//cli();								// read and write atomic
	TIMSK &= ~_BV(OCIE1A);

	if( display < 125 ) display = 125;	// just make sure, the timer
	if( display > 250 ) display = 250;  // is never out ouf 20ms grid
	OCR1A = 2500-display;

	TIMSK |= _BV(OCIE1A);
}


/**
 * \brief	the method moves the servo one complete cycle
 */
void demo_display(void) {
	set_servo(0);
	wait(100);
	set_servo(400);
	wait(100);
	set_servo(0);
	wait(100);
}


int main(void) {
	
	sei();
	ports_init();
	timer_init();
	uart_init(UART_BAUD_SELECT(38400,F_CPU));
	reset_input_buffer();
	demo_display();
	
	
	while(1) {
		work_uart();

		if((syscounter % 25) == 0) {	// about every 500ms
			reset_input_buffer();
			uart_putc('a'); 	// send a to receive values from master box
		}
		
		syscounter %= 1000;
	}
	
	return(0);
}

/**
 * \brief	this is our timer for PWM generation and system clock
 * 			the system clock varies a bit, but this does not matter
 */
ISR(TIMER1_COMPA_vect) {
	syscounter++;
	OCR1A = 2500-OCR1A;	// Das Servosignal wird aus der Differenz von
						// Periodenlänge (2500*0,008ms=20ms) und letztem
						// Vergleichswert (OCR1A) gebildet	
}