Button and LED module

• The XRP controller (Raspberry Pi Pico and other electronics), software (Micropython and XRPlib), and mechanical platform are designed to allow additional components to be added.

• In this exercise, we'll add a button and LED module.

• The parts needed include:

  • Grove - LED Button

  • Qwiic Cable - Grove Adapter (100mm)

  • Button_LED_board_connector (3D-print) - [https://www.thingiverse.com/thing:6669721]

  • (3) M2x12mm bolts and nuts

Button Programming

• The Button on the Button LED module is connected to the IO22 pin of the Pico. This is in parallel with the User Button on the XRP controller board.

• Therefore, the button on the module acts the same as the user button. The code in the Button exercise will work with the botton on the module.

• Use the same program from the Button exercise to test if the button on the module is working.

Note

• IO28 pin is connected to the XRP controller board battery voltage sensor. Connecting the Button module to this pin will interfere with reading the battery voltage when the button is pressed. This is not of importance for this exercise.

A better way to blink

• Here is a better way to blink an LED in Micropython using the timer and interrupt functionality:
  https://github.com/raspberrypi/pico-micropython-examples/blob/master/blink/blink.py
  Added while True ... board.wait_for_button to show that the LED continues to blink while waiting.
  (There are other Pico MicroPython example in this Gihub for you to explore.)

from XRPLib.board import Board

import time

from machine import Pin

from machine import Timer

board = Board.get_default_board()

led = Pin(28, Pin.OUT)

tim = Timer()

def tick(timer):

    global led

    led.toggle()

tim.init(freq=2.5, mode=Timer.PERIODIC, callback=tick)

while True:

  board.wait_for_button()

  print("Button!")