2b4a3pico71

In this article we look at an expansion board for the Raspberry Pi Pico that I found on one of my searches online which is designed to test all of the GPIO pins of the Raspberry Pi Pico.

Its a fairly niche board, it is low cost and doesn't really have that many use cases for most users but as always we have a look and give you couple of micropython code examples later on.

You can see this pictured below, the board contains 5 push buttons, 1 potentiometer and 20 leds connected to various GPIO pins.

Here is an image of the pins that this board uses and the function of them, as you can see all used.

This board has a couple of possible use cases

• As a demo board , test whether the GPIO pins of Pico are working
• As a basic expansion board, this module includes LEDs, buttons, and you can test ADC basic function.

Purchase

The board only costs about $2 from A;iexpress

Aliexpress store link

Code

There are a couple of code examples

This is a button test example, simply a case of press a button and an LED will light

from machine import Pin
import time

led = Pin(15, Pin.OUT)
button = Pin(12, Pin.IN, Pin.PULL_UP)
button1 = Pin(13, Pin.IN, Pin.PULL_UP)
button2 = Pin(14, Pin.IN, Pin.PULL_UP)
button3 = Pin(16, Pin.IN, Pin.PULL_UP)
button4 = Pin(17, Pin.IN, Pin.PULL_UP)

while True:
    if button.value() & button1.value() & button2.value() & button3.value() & button4.value() :                       
        led.low()
        time.sleep(0.5)
    elif button.value() | button1.value() | button2.value() | button3.value() | button4.value() :
        led.high()
        time.sleep(0.5)

This is an led test example, the LEDs will flash in sequence

from machine import Pin
import time

led=[28,27,1,0,22,21,3,2,20,19,5,4,15,18,7,6,11,10,9,8];

Pin(led[0], Pin.OUT)
Pin(led[1], Pin.OUT)
Pin(led[2], Pin.OUT)
Pin(led[3], Pin.OUT)
Pin(led[4], Pin.OUT)
Pin(led[5], Pin.OUT)
Pin(led[6], Pin.OUT)
Pin(led[7], Pin.OUT)
Pin(led[8], Pin.OUT)
Pin(led[9], Pin.OUT)
Pin(led[10], Pin.OUT)
Pin(led[11], Pin.OUT)
Pin(led[12], Pin.OUT)
Pin(led[13], Pin.OUT)
Pin(led[14], Pin.OUT)
Pin(led[15], Pin.OUT)
Pin(led[16], Pin.OUT)
Pin(led[17], Pin.OUT)
Pin(led[18], Pin.OUT)
Pin(led[19], Pin.OUT)


while 1:
    for i in range(len(led)):
        j=Pin(led[i], Pin.OUT)
        Pin(led[0], Pin.OUT).low()
        Pin(led[1], Pin.OUT).low()
        Pin(led[2], Pin.OUT).low()
        Pin(led[3], Pin.OUT).low()
        Pin(led[4], Pin.OUT).low()
        Pin(led[5], Pin.OUT).low()
        Pin(led[6], Pin.OUT).low()
        Pin(led[7], Pin.OUT).low()
        Pin(led[8], Pin.OUT).low()
        Pin(led[9], Pin.OUT).low()
        Pin(led[10], Pin.OUT).low()
        Pin(led[11], Pin.OUT).low()
        Pin(led[12], Pin.OUT).low()
        Pin(led[13], Pin.OUT).low()
        Pin(led[14], Pin.OUT).low()
        Pin(led[15], Pin.OUT).low()
        Pin(led[16], Pin.OUT).low()
        Pin(led[17], Pin.OUT).low()
        Pin(led[18], Pin.OUT).low()
        Pin(led[19], Pin.OUT).low()
        
        
        time.sleep(0.1)
        j.high()
        time.sleep(0.1)

In this article we look at the Pico Display Pack which is an 18-bit capable 240×135 pixel IPS display.

The pack also has four tactile buttons and an RGB LED that you can use as an indicator.

Here are the features

Features

1.14” 240×135 pixel IPS LCD screen
4 x tactile buttons
RGB LED
Pre-soldered female headers for attaching to Pico
Compatible with Raspberry Pi Pico.

Here is a pinout of display pack which show you the pins that are used for the 4 buttons, the RGB LED is controlled by 3 pins and the LCD is an SPI type.

You can power this using USB or external power

Getting started

The labels on the underside of Pico Display will show you which way round to plug it into your Pico – just match up the USB port with the markings on the board.

The easiest way to get started is by downloading and copying the custom MicroPython uf2 to your Pico, it includes all the libraries you’ll need to use our add-ons.

https://github.com/pimoroni/pimoroni-pico/releases/latest/

To be able to copy this file on to your Pico, you’ll need to put it into bootloader mode.

To do this, hold down the BOOTSEL button whilst plugging the USB cable into your computer – it should now show up as a drive called RPI-RP2.  Copy the downloaded .uf2 file across to this new drive. Your Pico will now reboot

Code examples

There are several good examples at https://github.com/pimoroni/pimoroni-pico/tree/main/micropython/examples/pico_display

Here is an example

# This example takes the temperature from the Pico's onboard temperature sensor, and displays it on Pico Display Pack, along with a little pixelly graph.
# It's based on the thermometer example in the "Getting Started with MicroPython on the Raspberry Pi Pico" book, which is a great read if you're a beginner!

import machine
import utime
import gc

# Pico Display boilerplate
import picodisplay as display
width = display.get_width()
height = display.get_height()
gc.collect()
display_buffer = bytearray(width * height * 2)
display.init(display_buffer)

# reads from Pico's temp sensor and converts it into a more manageable number
sensor_temp = machine.ADC(4)
conversion_factor = 3.3 / (65535)
temp_min = 10
temp_max = 30
bar_width = 5

# Set the display backlight to 50%
display.set_backlight(0.5)

temperatures = []

colors = [(0, 0, 255), (0, 255, 0), (255, 255, 0), (255, 0, 0)]


def temperature_to_color(temp):
    temp = min(temp, temp_max)
    temp = max(temp, temp_min)

    f_index = float(temp - temp_min) / float(temp_max - temp_min)
    f_index *= len(colors) - 1
    index = int(f_index)

    if index == len(colors) - 1:
        return colors[index]

    blend_b = f_index - index
    blend_a = 1.0 - blend_b

    a = colors[index]
    b = colors[index + 1]

    return [int((a[i] * blend_a) + (b[i] * blend_b)) for i in range(3)]


while True:
    # fills the screen with black
    display.set_pen(0, 0, 0)
    display.clear()

    # the following two lines do some maths to convert the number from the temp sensor into celsius
    reading = sensor_temp.read_u16() * conversion_factor
    temperature = 27 - (reading - 0.706) / 0.001721

    temperatures.append(temperature)

    # shifts the temperatures history to the left by one sample
    if len(temperatures) > width // bar_width:
        temperatures.pop(0)

    i = 0
    for t in temperatures:
        # chooses a pen colour based on the temperature
        display.set_pen(*temperature_to_color(t))

        # draws the reading as a tall, thin rectangle
        display.rectangle(i, height - (round(t) * 4), bar_width, height)

        # the next tall thin rectangle needs to be drawn
        # "bar_width" (default: 5) pixels to the right of the last one
        i += bar_width

    # heck lets also set the LED to match
    display.set_led(*temperature_to_color(temperature))

    # draws a white background for the text
    display.set_pen(255, 255, 255)
    display.rectangle(1, 1, 100, 25)

    # writes the reading as text in the white rectangle
    display.set_pen(0, 0, 0)
    display.text("{:.2f}".format(temperature) + "c", 3, 3, 0, 3)

    # time to update the display
    display.update()

    # waits for 5 seconds
    utime.sleep(5)

Lets look at a an example which shows the usage of the buttons

# This example shows you a simple, non-interrupt way of reading Pico Display's buttons with a loop that checks to see if buttons are pressed.

import picodisplay as display
import utime

# Initialise display with a bytearray display buffer
buf = bytearray(display.get_width() * display.get_height() * 2)
display.init(buf)
display.set_backlight(0.5)


# sets up a handy function we can call to clear the screen
def clear():
    display.set_pen(0, 0, 0)
    display.clear()
    display.update()


while True:
    if display.is_pressed(display.BUTTON_A):              # if a button press is detected then...
        clear()                                           # clear to black
        display.set_pen(255, 255, 255)                    # change the pen colour
        display.text("Button A pressed", 10, 10, 240, 4)  # display some text on the screen
        display.update()                                  # update the display
        utime.sleep(1)                                    # pause for a sec
        clear()                                           # clear to black again
    elif display.is_pressed(display.BUTTON_B):
        clear()
        display.set_pen(0, 255, 255)
        display.text("Button B pressed", 10, 10, 240, 4)
        display.update()
        utime.sleep(1)
        clear()
    elif display.is_pressed(display.BUTTON_X):
        clear()
        display.set_pen(255, 0, 255)
        display.text("Button X pressed", 10, 10, 240, 4)
        display.update()
        utime.sleep(1)
        clear()
    elif display.is_pressed(display.BUTTON_Y):
        clear()
        display.set_pen(255, 255, 0)
        display.text("Button Y pressed", 10, 10, 240, 4)
        display.update()
        utime.sleep(1)
        clear()
    else:
        display.set_pen(255, 0, 0)
        display.text("Press any button!", 10, 10, 240, 4)
        display.update()
    utime.sleep(0.1)  # this number is how frequently the Pico checks for button presses

Products

The following products are required