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pimoroni-pico/micropython/modules/pico_explorer/README.md

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Pico Explorer Base

Pico Explorer Base straps a whole host of physical computing goodies to your Pico - a vibrant 1.14" (240x240) IPS LCD screen, four switches, a piezo buzzer/speaker and a DRV8833 motor driver. It also has a bunch of handy accessible general purpose inputs and outputs and a built in breadboard.

You can buy one here!

The picoexplorer module contains constants you can use with our shared libraries to make it easy to draw to the screen and interface with the buttons, piezo buzzer and motor driver. You don't need to use the constants of course, you can skip the import pico_explorer and just enter the pin number/s if you prefer. There's a handy reference of what pins are used for which functions on the bottom of the board.

Board Functions

Display

Pico Explorer uses a shared Pico Graphics library to draw graphics and text on its screen. As a result, code written for our other Pico add-ons with a display should be easy to convert to run on Explorer.

Please note that the backlight on Pico Explorer is not dimmable (we needed the pins to hook up other functions) so set_backlight won't do anything on this board.

Here's a simple Hello World example that uses PicoGraphics to set up the display and draw some text on the screen.

from picographics import PicoGraphics, DISPLAY_PICO_EXPLORER

# Set up the display
display = PicoGraphics(display=DISPLAY_PICO_EXPLORER)

# Create a pen colour to draw with
WHITE = display.create_pen(255, 255, 255)

# Choose a font and switch to the white pen
display.set_font("bitmap8")
display.set_pen(WHITE)

# Display some text
display.text("Hello Explorer", 0, 0, scale=3)

# Update the screen
display.update()

Buttons

The four buttons, A, B, X and Y have corresponding constants set to their respective GPIO pins (12, 13, 14 and 15). They can be read with the shared pimoroni module which contains a Button class that handles button debounce and auto-repeat.

Button(button, invert=True, repeat_time=200, hold_time=1000)

To set up the buttons, first import the Button class from the pimoroni module and the pin constants from picoexplorer:

from pimoroni import Button
import picoexplorer

Then create instances of Button using our constants:

button_a = Button(picoexplorer.BUTTON_A)
button_b = Button(picoexplorer.BUTTON_B)
button_x = Button(picoexplorer.BUTTON_X)
button_y = Button(picoexplorer.BUTTON_Y)

To get the button state, call .read(). If the button is held down, then this will return True at the interval specified by repeat_time until hold_time is reached, at which point it will return True every repeat_time / 3 milliseconds. This is useful for rapidly increasing/decreasing values:

state = button_a.read()

It is also possible to read the raw button state without the repeat feature, if you prefer:

state = button_a.raw()

ADC

Pico Explorer's ADC channels are connected to Pico's ADC-capable pins (26, 27 and 28). You can read the voltages from them using the Analog class in the shared pimoroni module.

First import the Analog class from the pimoroni module and the pin constants from picoexplorer:

from pimoroni import Analog
import pico explorer

Then create instances of Analog using our constants:

 adc0 = Analog(picoexplorer.ADC0)
 adc1 = Analog(picoexplorer.ADC1)
 adc2 = Analog(picoexplorer.ADC2)

And read them like this

reading =  adc0.read_voltage()

Motors

Motors are driven by PWM via an onboard DRV8833. We'd recommend using our fully featured Motor library to drive them - here's a quick example:

import picoexplorer
from motor import Motor
import time

m = Motor(picoexplorer.MOTOR_1)

m.enable()

# run the motor full speed in one direction for 2 seconds
m.speed(1.0)
time.sleep(2)

# and in the opposite direction for 2 seconds
m.speed(-1.0)
time.sleep(2)

m.disable()

You can find much more info about working with motors in the Motor library documentation.

The red LED next to the motor connectors is part of the motor driver circuit - it will light up if the overvoltage/undervoltage/short circuit auto shutdown functions of the motor driver are triggered. It's not user controllable.

Audio

To make noise with Explorer, you must select one of the GP0 to GP7 pins to PWM for audio. You'll then need to connect this pin to AUDIO with a jumper wire.

To set up the buzzer, first import the Buzzer class from the pimoroni module and the pin constants from picoexplorer:

from pimoroni import Buzzer
import picoexplorer

Then create a Buzzer instance:

BUZZER = Buzzer(picoexplorer.GP0)

You can then play audio tones like this - frequency should probably be a number between 1 and 5000 if you have human ears.

buzzer.set_tone(frequency)

To make the buzzer be quiet, you can:

buzzer.set_tone(0)

GPIO

The 8 general purpose IO pins on Pico Explorer are connected to GP0 through GP7. You can use machine to read inputs in the same way as you would if you were using a Pico on its own.

import machine

GP0 = machine.Pin(0, machine.Pin.IN, machine.Pin.PULL_DOWN)

You can also use these pins as outputs, if you wanted to connect up stuff like LEDs:

import machine

GPO = machine.Pin(0, machine.Pin.OUT)

Note that if you're connecting external LEDs up to Explorer Base, GP0-7 have built in 100 Ohm resistors, so you don't need to include a resistor in your circuit to protect your LED from drawing too much current.

There's lots more info about how to use machine in the Raspberry Pi documentation.

Breakout Garden slots / I2C

The slots at the top of the board let you plug (I2C) Breakout Garden breakouts into Pico Explorer.

Pico Explorer uses GP20 and GP21 for its I2C interface - these pins differ from our default Breakout Garden pins so you will specify you're using a Pico Explorer when running breakout examples. You can use the constants in the shared pimoroni module to set up the I2C interface:

from pimoroni_i2c import PimoroniI2C
from pimoroni import PICO_EXPLORER_I2C_PINS

i2c = PimoroniI2C(**PICO_EXPLORER_I2C_PINS)

Alternatively, you can specify the pin numbers directly:

from pimoroni_i2c import PimoroniI2C

i2c = PimoroniI2C(sda=(20), scl=(21))

Pin Constants

Here's a list of constants that are available in picoexplorer, and the pin numbers that they correspond to on the Pico.

Buttons

  • BUTTON_A = 12
  • BUTTON_B = 13
  • BUTTON_X = 14
  • BUTTON_Y = 15

ADC

  • ADC0 = 26
  • ADC1 = 27
  • ADC2 = 28

Motors

  • MOTOR_1 = 8, 9
  • MOTOR_2 = 10, 11