Modulate complex signal on all gpio

Question

I need a signal at the output of the GIPO of approximately this shape.(sub-pulse in pulse)

How can this be implemented using PWM on PI? Im trying do it with RPIO,but his ancient GPIO pinout maybe not working for my Rpi 3 b+.

from RPIO import PWM
servo = PWM.Servo()
servo.set_servo(12, 10000)
PWM.add_channel_pulse(0, 12, start=200, width=2000)

Not Signal on pin. I'm confused in it and would like to try the built-in library to work with PWM, but I did not find there the possibility of sub-cycles. How else i can a signal of this form be output from different GPIO?

Answer 1

It seems, you should use code like this. Unfortunately, I have no chance to test it since I have no frequency meter or oscillograph.

import time
import pigpio

GPIO=12

pulse = []

#                          ON       OFF    MICROS
pulse.append(pigpio.pulse(1<<GPIO, 0,       5))
pulse.append(pigpio.pulse(0,       1<<GPIO, 5))
pulse.append(pigpio.pulse(1<<GPIO, 0,       5))
pulse.append(pigpio.pulse(0,       1<<GPIO, 1e7))

pi = pigpio.pi() # connect to local Pi

pi.set_mode(GPIO, pigpio.OUTPUT)

pi.wave_add_generic(pulse)

wid = pi.wave_create()

if wid >= 0:    
    pi.wave_send_repeat(wid)
    time.sleep(60)   # or another condition for stop processing
    pi.wave_tx_stop()
    pi.wave_delete(wid)

pi.stop()

Answer 2

The documentation suggests that simply passing a list of channels as the first argument to both GPIO.setup and GPIO.output will accomplish what you are asking.

chan_list = [11,12]    # add as many channels as you want!
                       # you can tuples instead i.e.:
                       #   chan_list = (11,12)
GPIO.setup(chan_list, GPIO.OUT)
GPIO.output(chan_list, GPIO.LOW)                # sets all to GPIO.LOW

Answer 3

I have had much better PWM experience with pigpio as compared to RPi.GPIO. Wiringpi is also good but pigpio's PWM support is much better IMO.

The documentation has a few functions for generating PWM on any pin:

http://abyz.co.uk/rpi/pigpio/python.html#set_servo_pulsewidth http://abyz.co.uk/rpi/pigpio/python.html#set_PWM_dutycycle

Do you *have* to use RPi.GPIO? I understand that this is not an exact answer, but I hope it at least points you in the right direction.