Precise pulse duration

Reply to Precise pulse duration on Wed, 23 May 2018 07:43:42 GMT

berni — Wed, 23 May 2018 07:43:42 GMT

I am trying to to do a pulse of a given duration (e.g. 2.000 ms) on a digital output. Ideally, I don't want to stop the code with a while True:

At the moment, I am trying with Timer.Alarm but I have the feeling that I am not getting an accurate timing.

p_out = Pin('P19', mode=Pin.OUT)

def pulse_off(timer):
    p_out(0)

# Perform a pulse of 2000ms
p_out(1)
pulse_timer = Timer.Alarm(self.pulse_off, ms=2000, periodic=False)

Could anyone give some advice on the most accurate way to perform a pulse? Thank you in advance!

Reply to Precise pulse duration on Wed, 23 May 2018 08:02:35 GMT

robert-hh — Wed, 23 May 2018 08:02:35 GMT

@berni The RMT class could be used for that.

Reply to Precise pulse duration on Wed, 23 May 2018 08:07:14 GMT

jmarcelino — Wed, 23 May 2018 08:07:14 GMT

@berni
Indeed RMT would be the best way to generate pulses, https://docs.pycom.io/chapter/tutorials/all/rmt.html.

The maximum single pulse width is ~ 100ms but you should be able to chain multiple together

Reply to Precise pulse duration on Wed, 23 May 2018 08:35:30 GMT

berni — Wed, 23 May 2018 08:35:30 GMT

Thank you @robert-hh and @jmarcelino! I will give it a go and report back. :-)