Move servo with pushbuttons | C | Atmel Studio

Question

I am now working on a solar tracker project with the ATMEGA1284P and, after configuring PWM it is time for discovering the mechanical limitations of the tracker so I can define boundaries for the servos.

For this, I have prepared a simple code. I know PWM is working correctly (checked with scope also) but I just can't get this code to work. The idea is to move a servo with two pushbuttons (connected to gnd) and later configure UART so I can send the current servo position to my computer. I've tried also go call the pwm_set1 function outside of the if loops but it doesn't respond at all.

The switches are also wired up correctly and I've also checked with voltmeter on the uC pins and they are both working fine, i.e. GND when pressed, pull-up resistors configured as yo can see in the code below.

Any suggestions are highly appreciated. Thank you! Cheers, Rui Moreno.

#ifndef F_CPU
#define F_CPU 1000000L   // 1 Mhz
#endif
#include <avr/io.h>
#include <avr/portpins.h>
#include <util/delay.h>

void pwm_init(){
    // Configurar o Waveform Generation Mode.
        // Para modo de fast PWM, WGM11, 12 e 13 têm que estar a 1
    TCCR1A |= 1<<WGM11 | 1<<COM1A1 | 0<<COM1A0;     // COM1A1 para configurar PWM em modo non-    inverted (devido ao BJT) | anterior:COM1A1 e COM1A0 para configurar PWM em inverted mode
    TCCR1B |= 1<<WGM13 | 1<<WGM12 | 1<<CS10;      // CS10 serve para selecionar o prescaler     (nenhum, neste caso)

    //Definir o período para PWM
    ICR1 = 19999;
    OCR1A = ICR1 - 550;  // posição inicial do servo
};

void pwm_set1(uint16_t x){
    OCR1A = ICR1-x;
}

int main(void)
{
    DDRD |= 0xFF; //Configurar Porta D como saída em todos os pinos

    pwm_init();
    uint16_t posx = 550;

    //configurar pinos C1 e C2 como entrada para os switches left e right (just in case)
    DDRC &= ~(1 << PC2);
    DDRC &= ~(1 << PC3);
    //pull-up resistors nos pinos C1 e C2
    PORTC |= (1 << PC2);
    PORTC |= (1 << PC3);


    while(1)
    {
            if ((PINC & (1<<2)) == 0){
                posx+=1;
                pwm_set1(posx);
            }

            if ((PINC & (1<<3)) == 0){
                posx-=1;
                pwm_set1(posx);
            }
    }    
}

Answer 1

I've managed to get the switches working by using interrupts:

ISR(INT0_vect) {        
    if (bit_is_set(PIND, PIND2)) {   //PD2
        OCR1A+=20;
    }
    else{}
}

ISR(INT1_vect) {        
    if (bit_is_set(PIND, PIND3)) {   //PD2
        OCR1A-=20;
    }
    else{}
    }

void initInterrupts(void) {
    EIMSK |= ((1 << INT0)|(1 << INT1));     //enable INT0 and INT1
     //EICRA |= (1 << ISC01);      //trigger on falling edge
    sei();                          // set (global) interrupt enable bit
   }

Still a bit raw, as what I want is for the interrupts to update a variable and then pwm_set1 function under main with that updated variable. Also I'll have to implement some sort of debouncing mechanism.

Cheers, Rui Moreno.