create waves with pigpio on raspberry pi

generic-wave-pigpio.sh

#!/usr/bin/env bash
# eg. bash generic-wave-pigpio.sh 25 3000 10
#
# Creates 3kHz 10% duty cycle on GPIO 25
# 3kHz 10% duty cycle -> 30microseconds on, 300 microseconds off

# If accuracy problems, /boot/config.txt dtparam=audio=off

#set -x

G="$1"
freq="$2"
duty="$3"

usage() {
  echo "$0 GPIO freq duty"
  exit 1
}

[ $G ] || usage
[ $freq ] || usage
[ $duty ] || usage


period=$(python -c "print(1000000/$freq)")
on=$(python -c "print(int($period *$duty/100.0))")
off=$((period - on))

pigs m $G w
pigs wvag $((1<<$G)) 0 $on 0 $(( 1<<$G)) $off
wid=$(pigs  wvcre)
pigs wvtxr $wid
# stop waveform by running:
#   pigs wvhlt

hardware-pwm.sh

#!/usr/bin/env bash

# GPIO 18 30kHz 20% duty cycle

pigs 18 30000 200000

monitor-freq.py

#!/usr/bin/env python3

import sys
import time
import pigpio

last = [None]*32
cb=[]
lastdiff=0


def cbf(GPIO, level, tick):
  global lastdiff

  if last[GPIO] is not None:
    diff = pigpio.tickDiff(last[GPIO], tick)
    twosamplesaverage = (diff + lastdiff)/2
    #print("G={} l={} d={}".format(GPIO, level, int(1000000.0/twosamplesaverage)))
    print("GPIO={}  freq={}Hz".format(GPIO, int(1000000.0/twosamplesaverage)))
    lastdiff=diff
  last[GPIO] = tick 

pi = pigpio.pi()
if not pi.connected:
  sys.exit()




g=int(sys.argv[1]) if len(sys.argv) == 2 else 25 
c = pi.callback(g, pigpio.RISING_EDGE, cbf)

try:
  while True:
    time.sleep(60)
except KeyboardInterrupt:
  c.cancel()

monitor.py

#!/usr/bin/env python3

import sys
import time
import pigpio

last = [None]*32
cb=[]

def cbf(GPIO, level, tick):
  if last[GPIO] is not None:
    diff = pigpio.tickDiff(last[GPIO], tick)
    print("G={} l={} d={}".format(GPIO, level, diff))
  last[GPIO] = tick

pi = pigpio.pi()
if not pi.connected:
  sys.exit()

g=int(sys.argv[1]) if len(sys.argv) == 2 else 25
c = pi.callback(g, pigpio.EITHER_EDGE, cbf)

try:
  while True:
    time.sleep(60)
except KeyboardInterrupt:
  c.cancel()

pigpiod.service

[Unit]
Description=Daemon required to control GPIO pins via pigpio
[Service]
ExecStart=/usr/bin/pigpiod -l -n 127.0.0.1
ExecStop=/bin/systemctl kill pigpiod
Type=forking
[Install]
WantedBy=multi-user.target

start-pigpiod.sh

#!/usr/bin/env bash
sudo systemctl start pigpiod