I'm trying to get 50 pulse train of 20Hz with a Ton of 2.1ms from arduino pin 11. Is it possible?
According to a piece of code I found on the old forum this is what I get. Is this correct from you?
int pulseNumber = 50; // Number of pulses in pulse train
double frequency = 20; //frequency in Hz
double dutyCycle = .042; //duty cycle
unsigned long milliseconds = 10; //delay between pulse sets
int on;
int off;
double period;
#define fastWrite(_pin_, _state_) ( _pin_ < 8 ? (_state_ ? PORTD |= 1 << _pin_ : PORTD &= ~(1 << _pin_ )) : (_state_ ? PORTB |= 1 << (_pin_ -8) : PORTB &= ~(1 << (_pin_ -8) )))
// the macro sets or clears the appropriate bit in port D if the pin is less than 8 or port B if between 8 and 13
void setup() {
pinMode(11, OUTPUT); // set outPin pin as output
}
void loop() {
period = (1 / frequency) * 1000000;
on = dutyCycle * period;
off = period * (1-dutyCycle);
// call Pulse function for n = pulseNumber
for (int i=1; i<=pulseNumber; i++) {
Pulse(on, off);
}
delay(milliseconds); // delay between pulse sets
}
void Pulse(int on, int off) {
fastWrite(7, HIGH); // set Pin high
delayMicroseconds(on); // waits "on" microseconds
fastWrite(7, LOW); // set pin low
delayMicroseconds(off); //wait "off" microseconds
}
I think you would be much better off using timer 2, that controls pin 11 in PWM mode. The problem with what you have written is that anything else that your arduino code does is going to affect the time of your pulses. Also the time will jitter a bit because of background interrupts. So how important is the accuracy and what else does your system need to do?
Grumpy_Mike:
I think you would be much better off using timer 2, that controls pin 11 in PWM mode. The problem with what you have written is that anything else that your arduino code does is going to affect the time of your pulses. Also the time will jitter a bit because of background interrupts. So how important is the accuracy and what else does your system need to do?
Yes, I'm sorry. In the final sketch I'm going to use pin 11 not pin 7. Pin 7 is used from the sketch I've found on the old forum.
What I've to do is sending a 20Hz 50 pulse train with 2.1ms T-on to an hitec digital servo to move it. Then another 20Hz 50 pulse train with 0.9ms T-on to put it to start position.
After and before that I do other operations. Could you please be more specific? I'm not an expert in pwm programming and this is my first time at it.
Then you are a fool, using the servo libary you just set the position and the pulses are generated automatically in the background. Without this sort of programming it will be impossible for you to do anything other than keep the servo in place.
Grumpy_Mike:
Then you are a fool, using the servo libary you just set the position and the pulses are generated automatically in the background. Without this sort of programming it will be impossible for you to do anything other than keep the servo in place.
Thank's a lot all. I will be using an Hitec servo that need a Ton of 2.1ms, T=20ms at 50Hz to go to end position (sorry for error, not 20Hz). And it need Ton 0.9msec to reach start position.
