Guide

How to create a simple Focus Timer using Raspberry Pi Pico

Sam

Mar 5, 2023 • 3 min read

In this guide we will create a simple yet extremely useful focus timer using Raspberry Pi Pico development board.

You can use this timer to focus on tasks at hand. The technique also known as the Pomodoro Technique.

Focus timer demo

Code is licensed under the Open Source MIT License

What you need

Raspberry Pi Pico or compatible board with CircuitPython installed
LED strip (WS2812, also known as NeoPixel)
1M Ohm Resistor
Jumper wires
USB cable to connect to the power source

Wiring

You can use any Raspberry Pi Pico board. For this guide we chose a Pimoroni Pico Lipo since it has a handy battery charger if we wanna make our timer mobile.

LED connection

Connect Pi Pico Ground and 3v3 to LED strip Ground and VIN
Connect GP16 to LED strip data in

Touch sensor

Connect our 1M Ohm resistor between GP15 and Ground
Connect a piece or wire to GP15, this will be our touch sensor which will control the timer

Libraries

These libraries are licensed under the Open Source MIT License

Adafruit Neopixel

Copy neopixel.mpy to lib/

neopixel.mpy.zip

2 KB

Thats it, we can now code our awesome focus timer.

The code

Copy the following code in code.py file on your development board. Be sure to check out the inline comments for the explanation.

import time, os, board
import neopixel, touchio
from rainbowio import colorwheel

OFF = (0, 0, 0)
WHITE = (255, 255, 255)
RED = (255, 0, 0)
YELLOW = (255, 150, 0)
GREEN = (0, 255, 0)
CYAN = (0, 255, 255)
BLUE = (0, 0, 255)
PURPLE = (180, 0, 255)

# Settings
pixels_count = 8
# How many LEDs on a strip to glow on each touch
pixels_increment = 1
# Brightness, max is 1, go nuts if you like
pixels_brightness = 0.1
# Each LED is a 5 minutes timer
timer_seconds = (60 * 5)
# See the color constants above, define a new color if you like
color = WHITE

# Initialise lights
pixel_pin = board.GP16
pixels = neopixel.NeoPixel(pixel_pin, pixels_count, brightness=pixels_brightness, auto_write=True)

# Initialise touch pin
touch_pin = touchio.TouchIn(board.GP15)

on_count = 0
prev_count = 0

# Helper to get rounded time monotonic
def time_monotonic():
    return round(time.monotonic())

# A cool rainbow effect, we will use this on startup and when the timer ends
def rainbow_cycle(wait, count):
    for color in range(count):
        for pixel in range(len(pixels)):  # pylint: disable=consider-using-enumerate
            pixel_index = (pixel * 256 // len(pixels)) + color * 5
            pixels[pixel] = colorwheel(pixel_index & 255)
        pixels.show()
        time.sleep(wait)
    pixels.fill(OFF)

# Glows or switches off the LEDs
def update_pixels():
    pixels.fill(OFF)
    if on_count:
        for p in range(on_count):
            pixels[p] = color
        
rainbow_cycle(0.01, 80)
start_time = time_monotonic()

while True:
    prev_count = on_count
    now_time = time_monotonic()
    if touch_pin.value:
        # Detected a touch
        if on_count >= pixels_count:
            # Still less than 'pixels_count', increase the timer count
            on_count = 0
            update_pixels()
        else:
            # Cant go above 'pixels_count', reset to 0
            on_count += pixels_increment
            update_pixels()
        # Touch will always reset the start time
        start_time = time_monotonic()

    elapsed_min = now_time - start_time
    if elapsed_min >= timer_seconds and on_count:
        # Each tick (timer_seconds) will trigger this
        # Reduce 'pixels_increment' which will switch off 'pixels_increment' number of LEDs
        start_time = time_monotonic()
        on_count -= pixels_increment
        update_pixels()
        if on_count is 0:
            # A little show for you
            time.sleep(1)
            rainbow_cycle(0.01, 80)

    time.sleep(0.2)

Test

Simply run code.py or you can disconnect/connect your board which will automatically run your code.

On startup you would see a nice rainbow light show for few seconds. To set the timer, touch the wire connected on pin GP15, each touch should increment the timer.

Sit back and focus on the given task, once the timer ends it will again show a little rainbow to celebrate.