Install PyCall on Raspberry PI and try using GPIO's library for Python from Ruby

Introduction

I thought about doing something with the Raspberry Pi that I had left for a long time, but I can't think of a theme ... (sweat)

As a result of thinking for a while, I decided to try how versatile PyCall I have been using from the other day can be used, so I put PyCall in Raspberry Pi and made a circuit to detect ON / OFF of the switch and run it with Ruby Saw.

[Reference site] Raspberry Pi GPIO input / output sample (Python, C language, shell script)

Install PyCall

Since Ruby 2.1 was included immediately after the initial installation, I will use it as it is. Install PyCall with the following command.

python

$ sudo apt install -y ruby-dev
$ sudo gem install --pre pycall

Check the source code for Python

Let's take a look at the source code published on the reference site mentioned above.

gpio_input.py

#!/usr/bin/python
 
import RPi.GPIO as GPIO
import time
 
IO_NO = 4
 
print("press ^C to exit program ...\n")
 
GPIO.setmode(GPIO.BCM)
GPIO.setup(IO_NO, GPIO.IN)
 
try:
 while True:
  print(GPIO.input(IO_NO))
  time.sleep(1)
except KeyboardInterrupt:
 print("detect key interrupt\n")
 
GPIO.cleanup()
print("Program exit\n")

When I try it out ...

python

$ python gpio_input.py
press ^C to exit program ...
1
1
1
0
0
1
1
1
0
1
1
^Cdetect key interrupt

Program exit
$

It seems that when you press the button, it becomes 0, and when you release it, 1 is displayed. For the time being, I found that the wiring was correct.

Rewrite using PyCall

If you use the sample code as it is, it will be a little dull, so let's change it so that it is displayed while counting the number of ON / OFF times.

gpio_input.rb

require 'pycall/import'
include PyCall::Import

pyimport 'RPi.GPIO', as: 'gpio'

io_no = 4

status = 1
buff = 1

cnt = 0

puts "press ^C to exit program ...\n"

gpio.setmode.(gpio.BCM)
gpio.setup.(io_no, gpio.IN)

# 「Ctrl」+Stop at "C"
Signal.trap(:INT) do
  puts "detect key interrupt\n"
  gpio.cleanup.()
  puts "Program exit\n"
  exit 0
end

loop do
  status = gpio.input.(io_no)
  if buff != status
    if status == 1
      puts "OFF"
    else
      cnt += 1
      puts "ON(#{cnt})"
    end
  end
  
  buff = status
  sleep 0.5
end

By the way, in Ruby, variables starting with uppercase letters cannot be defined (I've heard that ...), so I change them to lowercase letters.

Operation check

Execute the command and press the button several times ...

python

$ ruby gpio_input.rb
press ^C to exit program ...
ON(1)
OFF
ON(2)
OFF
ON(3)
OFF
^Cdetect key interrupt

Program exit
$

It was done (^-^)

If you use a gem called PI Piper, you can do it with Ruby without any problem, so you don't need to use PyCall ...

Well, what should I do next?