I am trying to make a servo controller that have a higher resolution than the ATtiny85 8-bit timer/counter. So far I have managed to get about 2000 positions on my servo (1µs/step) within a time frame of 21'000 µs. I have also managed to move 5 servos sequential and with different speed, but now I want to move them synchronous.
My biggest problem is that I don't get how I should make it happen! I have looked around on other servo codes including servo8bit library and tried to find a way. It seems that most of the examples uses compare match ISR to move the servos "at the same time", my problem is that I have a 16-bit integer that I want to compare.
Is there a way to do some magic so I can use the 8-bit compare match ISR with my 16-bit integer? Or does anyone of you have some other suggestions on how I can move my servos synchronous without using compare match ISR?
I hope my questions make sense!
Since I don't really have any code to show yet (only flawed attempts without compar match ISR that makes no sense) I post the link to my TinyServo code if it helps.
EDIT 1:
Here is the part of the code I mentioned and didn't post the first time:
void servoMove(void)
{
uint16_t nextPulse = hPulse[0];
timerSetup (); //16-bit setup for counter
for (i = 0; i < sizeof(servo)/sizeof(servo[0]); i++)
{
if ( (oTime > nextPulse) && (channel < sizeof(servo)/sizeof(servo[0])) ) //check if HIGH pulse (pos) is done
{
PORTB &= ~(1 << servo[channel]);
if (i+1 < sizeof(hPulse)/sizeof(hPulse[0]))
{
nextPulse += hPulse[i+1];
}
channel++;
}
else
{
channel = 0;
oTime = 0; //resets 16-bit variable
tot_overflow = 0; //resets tot_overflow variable
TIFR |= (1 << TOV1); // clear counter1 overflow-flag
TCNT1 = 0; //resets Timer/Counter1
}
}
for (i = 0; i < sizeof(servo)/sizeof(servo[0]); i++)
{
if ( (oTime > tPulse - nextPulse) && (channel < sizeof(servo)/sizeof(servo[0])) ) //check if LOW pulse (period) is done
{
PORTB |= (1 << servo[channel]);
nextPulse -= hPulse[i];
channel++;
}
}
}
void servoPosSet(volatile uint16_t pos[], uint8_t size)
{
for (i = 0; i < size; i++)
{
hPulse[i] = pos[i];
}
}
int main(void)
{
TCCR1 |= (1 << CS12); //set Timer/Counter1 prescaler to increment every 1 µs (PCK/8)
for (channel = 0; channel < size); channel++)
{
DDRB |= (1 << servo[channel]); //sets PB0-PB4 as output pins
}
channel = 0;
uint16_t pos[] = {2000, 1500, 1900, 1300, 1700};
uint8_t size = 5;
while(1)
{
servoPosSet(pos);
servoMove();
}
}
EDIT 2:
This is an illustration of how I think the code should work:
...but it does not!