Raspberry Pi Pico & Pico Explorer Workout

by tonygo2

9.3K2331

Intro: Raspberry Pi Pico & Pico Explorer Workout

In this Instructable I'm going to demonstrate the new Raspberry Pi PICO microcontroller board for Physical Computing and Graphics using the Pimoroni PICO EXPLORER.

I am going to assume that you have installed the Pimoroni UF2 file to your Pico, installed the Thonny Editor on your computer, know how to connect your Pico to your computer's USB port, enter and run code from Thonny.

(I've updated this tutorial to use the updated Pimoroni UF2 file 0.0.7 - 17th Feb 2021)

Pimoroni have supplied a few graphics commands - screen clear, filled rectangles and circles, pen colours, pixel, text string and text character printing to the screen.

This demonstration adds lines, hollow rectangles and circles, bar and line graphs, user defined characters and how to combine them in various ways to scroll text cross the screen and react to physical changes as buttons are pressed and a potentiometer knob is turned.

I hope you will find it useful.

STEP 1: Wire Up

The picture shows how to wire up the breadboard. Once this has been done push the potentiometer into the breadboard at the right side to cover the two short black and orange wires. The wiper leg should be at the top, between the two wires.

The demonstration will work without the components and demonstrates the graphical capabilities of the board but with less user control.

At this point you can download the MicroPython file and run it.

The following pages look at the code and add comments/observations

STEP 2: Basic Boilerplate and Procedures


This sets up the display and has routines to clear the screen to black and write titles for each section of code.

STEP 3: Lines and Boxes

These routines provide vertical and horizontal lines, lines between two points and hollow rectangles.

STEP 4: Alignment and Circles

Here are routines to update the screen and pause a short while, left align text by inserting extra spaces and two methods of drawing hollow circles.

STEP 5: Bar Graph and User Defined Characters (small)

These routines draw a bar graph and show how to define 7x5 pixel characters and display them at twice the size. The pixels are so small on this screen that at normal size you cannot really see them effectively.

STEP 6: Larger Defined Characters

This routine draws the predefined characters at size 3.

STEP 7: Basic Stuff

Here we start the main program showing lines, circles, a box and predefined characters at two sizes

STEP 8: Character Set

Notice that the text can set to various sizes. Size 1 is very difficult to read and size 6 is rather crude. There are no lower case letters - probably to save space. The type face is an unusual choice.

'~' has been replaced at the end with a right leaning single quote.

Long strings will text wrap at a 'space' character.

STEP 9: A Load of Lines

Lines at any angle and drawn pretty quickly.

STEP 10: Sine and Cosine Curves

Notice the speed difference with display.update() inside and outside the loop

STEP 11: Text on a Path

Pretty easy to do

STEP 12: Scrolling Text on a Path - Setup

STEP 13: Scrolling on a Path - the Loop

I was impressed by the speed the pico and display managed this. There is a great deal going on.

STEP 14: Physical Computing - Potentiometer, LED With PWM, Bar Graph and Button

I found that the readings from the pot would not give a proper zero at the low end and as this need numbers exactly between 0 and 255 inclusive I had to 'tidy up' the raw ADC readings with a bit of code.

Do not run your display too bright. I found a bit of burn in while trying to take the photographs.

Notice the use of the button to break out of the loop.

STEP 15: Tidy Up and Finish

I put the LED pin back to a normal state after using it for PWM

I hope this tutorial has been useful. Most of the routines can also be used with the smaller Pimoroni Pico Display screen.

17 Comments

bwsorrell 1 year ago

Thank you for this tutorial, it really hlped me get to grips with the Pico Explorer as an introduction to the Pico!

wd-feyd 1 year ago

I see that several people have had problems recently with running this example.

The micropython libraries have been updated many times by Pimoroni since this example was posted. If you are using the latest version you will need to make several changes to the code to get it to work.

You can find the information about how to use the latest picographics library on the pimoroni github page here:

https://github.com/pimoroni/pimoroni-pico/tree/mai...

I think it is a useful experience for anyone interested in learning micropython and programming their Pico to take a look there and attempt to update this example themselves to work with the new library version rather than just have me post a fully fixed version for you.

But to point you in the general direction, some basics of what you need to change are that you now initialise the display like this:

from picographics import PicoGraphics, DISPLAY_PICO_EXPLORER
display = PicoGraphics(display=DISPLAY_PICO_EXPLORER)

You can get the width and height values for the display with:

width, height = display.get_bounds()

and to use pens you now define a pen with the create_pen method, and make it the active pen with the set_pen method, so the blk() routine would now become something like this:

def blk():
black_pen = display.create_pen(0,0,0)
display.set_pen(black_pen)
display.clear()
display.update()

Hope this gets anyone coming across this example now heading in the right direction.




basicbare 2 years ago

I've wired the breadboard as per the diagram and instructions, and have tried to run the ExplorerWorkoutV3.py file. When I run it, I get the following traceback message:

Traceback (most recent call last):
File "<stdin>", line 5, in <module>
ImportError: no module named 'picoexplorer'

This refers to "import picoexplorer as display" in the script. However, I can't find "picoexplorer" as a module anywhere. What am I missing? What am I doing wrong?

Thanks!

user1818 2 years ago

Hi, I'm a noob. I'm trying to run the python file ExplorerWorkoutV3.py on a Pico Pi with Pico attached to a Pico Explorer, but without the optional additional components.
When I try to run it on my Pico with Thonny, I get the following error:
"Traceback (most recent call last):
File "<stdin>", line 8, in <module>
AttributeError: 'module' object has no attribute 'get_width'"
line 8 reads:
width = display.get_width()
Am I doing something wrong?
I know the Pico and explorer are connected correctly to the computer as I can run other programs through Thonny.
Thanks!

Toldcodger 2 years ago

It’s not your fault if you are using the latest version of the Pimoroni uf2. Version 1.19.
Hopefully Tony will update this soon.
Try commenting out the width and height lines.
I had problems with the colours too.

altgreenfan 2 years ago

Only your example works for me :) The ones from the store have a problem with the library, I know you have to use their version. Can't upload uf2 file as thonny library

tonygo2 3 years ago

Les Wright has solved the lowercase characters problem. Written in pure Python you can now get lower case characters and define your own.

peterhczaja 4 years ago

Thanks Tony, nice easy instructions, and it works (of course :) )

romilly 4 years ago

You’ll need to comment out the line that sets the backlight intensity as this method has been removed in the current (0.0.7) Pimoroni uf2

tonygo2 4 years ago

Thanks, I've added a note.
PS I've still got your expansion boards from when the Mk I Pi came out.

Jason.1 4 years ago

How bad is the burn-in ?

do you think it's likely just to be your unit or maybe more widespread ?

I'm very tempted but may hold off if this display problem is common !

tonygo2 4 years ago

Not a problem. I'd left the unit on with full white on the circle while I had lunch. I only noticed when I took the photos, which were a bit over exposed. (Contrast is tricky when snapping screens.) I cannot see any problem with the naked eye now and I've been using the unit a great deal. Get the base - it is great fun.
I think the backlight command is being withdraw - no backlight in the screen? See the Github. Just avoid colour (255,255,255) in large areas for too long.

Jason.1 4 years ago

Hi Tony
I really appreciate you taking the time to give me such a complete answer!
Just ordered one to add to my seemingly endlessly expanding collection of Micro_controllers & expansion boards!
Really looking forward to seeing what I can do with it

Thanks Again

Stay Safe

doidgy1 4 years ago

Thank you, well written and easy to follow.
Oh and it works :)

tonygo2 4 years ago

Thank you, Great little screen.