对标准I / O端口（ATmega32 AVR）上的伺服的多个控制？

Question

I'm basically trying to perform a chain of actions on multiple servo motors when a particular button is pressed.The following code works fine but can only perform a single movement on multiple servos ie when the button is pressed Servo1 moves to 900 and servo2 to 1500 else they go back to standard positions.

What I want to achieve is a set of movements, for instance when the button is pressed I want both the servos to swing(0 to 180 to 0(3 different movements)). I tried to use a delay function and change the values of the servo but then it wouldn't work, which im assuming is because the delay becomes greater than my Fast PWM time period.

void main()
{
DDRB = 0xFF;
DDRC = 0x00;
PORTC = 0XFF;

TCCR1A |= 1<<WGM11;
TCCR1B |= 1<<WGM12 | 1<<WGM13 | 1<<CS10;
TIMSK  |= 1<<OCIE1A;

ICR1=19999; 

sei();

uint16_t Servo1 = 2000, Servo2 = 900;

while(1)
{
    if(bit_is_clear(PINC,0)) 
  {
      Servo1 = 900, Servo2 = 1500;
     }
 else{
     Servo1 = 1500, Servo2=2200;
 }
  if(TCNT1>=800 && TCNT1<=2400)
  {
       if (TCNT1 >= Servo1 && bit_is_set(PORTB,PINB0)) PORTB &= ~(1<<PINB0);
       if (TCNT1 >= Servo2 && bit_is_set(PORTB,PINB1)) PORTB &= ~(1<<PINB1); 
  } 

}
}

ISR(TIMER1_COMPA_vect)
{
 PORTB = 0xFF;  
}

How do I go about the same? Any help appreciated.

Answer 1

It seems you are implementing your PWM manually using the Timer1, that means that you can't add delays as those from <util/delay.h> so, your only option is implement something similar to a state machine.

define a variable for the state where STATE0 will be the waiting state, STATE1 will be the first movement STATE2 the second movement and so on...

then define a 'time table' to define how much time it'll wait on each state, (ideally it should be a condition table but anyway...)

enum{ STATE0,STATE1,STATE2};// from 0 to 2
int time[3]={0,500,500}; //for state 0 it'll wait the button
volatile int time_counter=0; //needs to be volatile 'cos it's used inside the interrupt
int state = STATE0;

void main()
{
DDRB = 0xFF;
DDRC = 0x00;
PORTC = 0XFF;

TCCR1A |= 1<<WGM11;
TCCR1B |= 1<<WGM12 | 1<<WGM13 | 1<<CS10;
TIMSK  |= 1<<OCIE1A;

ICR1=19999; 

sei();

uint16_t Servo1 = 2000, Servo2 = 900; // are these initial values ok for STATE0?

while(1)
{
    //eval state
    switch(state){
        case STATE0:
            if(bit_is_clear(PINC,0)) // if button
            {
                //change state
                state=STATE1;
                time_counter=0;
                //do task
                Servo1 = 900, Servo2 = 1500;
            }
        break;
        case STATE1:
            if(time_counter>time[state])
            {
                //change state
                state=STATE2;
                time_counter=0;
                //do task
                Servo1 = 1500, Servo2 = 2200;
            }
        break;
        case STATE2:
            if(time_counter>time[state])
            {
                //change state
                state=STATE0; // go to wait the buton again
                time_counter=0; // not necesary but anyway...
                //do task
                Servo1 = 2000, Servo2 = 900;
            }

        break;
    }
    //do the pwm stuff
    if(TCNT1>=800 && TCNT1<=2400)
  {
       if (TCNT1 >= Servo1 && bit_is_set(PORTB,PINB0)) PORTB &= ~(1<<PINB0);
       if (TCNT1 >= Servo2 && bit_is_set(PORTB,PINB1)) PORTB &= ~(1<<PINB1); 
  } 

}
}

ISR(TIMER1_COMPA_vect)
{
 PORTB = 0xFF;  
 time_counter++; //here we count the pwm cycles...
}

I haven't check your timer configuration, hence I actually don't know if the waiting time of 500 cycles should be enough or too much, but you should change the time[] table according your tests...

it's also recommended to use 2 switches, one to check the condition and change the states accordingly, and the other one to actually do the task for the actual state... I just got lazy and did both in a single switch...

also as you are using an enum{}, it's better that you rename the states to soemthing meaningful, like STATE_WAIT or STATE_POS_180 or STATE_LOCATION_A...