← MicroPython on Pi Pico and Projects

Project 1.2

Project 1.2: Flashing MicroPython with Thonny

Get MicroPython running on your Pico for the first time, using Thonny

Checklist (covers 1.2 & 1.3) Slides (covers 1.2 & 1.3)

← Project 1.1 Wiring Three LEDs Project 1.3: Files on Your Pico, and Your First REPL Commands →

Check whether you even need this

Open Thonny and look at the bottom-right corner of the window. If it already shows MicroPython (Raspberry Pi Pico) with your Pico connected, MicroPython is already installed. Skip ahead to Project 1.3.

If it doesn’t, or your Pico shows up as a plain removable drive instead, keep going. This is likely the first time your specific Pico has had MicroPython put on it.

Put your Pico into BOOTSEL mode

Hold down the BOOTSEL button on top of your Pico. While still holding it down, plug your Pico into the computer with a micro USB cable. Count to three, then let go of the button. Your Pico should appear as a plain removable drive, not as a MicroPython device yet.

The first time you do this, your Mac will ask whether to allow the accessory to connect. Click Allow.

A macOS dialog titled Allow accessory to connect, asking whether to connect Raspberry Pi RP2350 Boot to this Mac, with Don't Allow and Allow buttons.
Your Mac asking permission to connect to your Pico in BOOTSEL mode

Install MicroPython from inside Thonny

With your Pico in BOOTSEL mode, use Thonny’s own installer rather than downloading anything by hand:

  1. Click the interpreter indicator in Thonny’s bottom-right corner.
  2. Look for an option to install or update MicroPython on the device.
  3. Choose the variant that matches your board exactly: Raspberry Pi Pico 2 W, not plain Pico 2. Picking the wrong variant is the most common mistake here.
  4. Click Install, and wait. Don’t unplug your Pico while this runs.
Thonny's interpreter menu open, showing Install MicroPython highlighted above Install CircuitPython and Configure interpreter options.
The interpreter menu in Thonny's bottom-right corner, with Install MicroPython selected

When it finishes, Thonny should reconnect automatically and show MicroPython (Raspberry Pi Pico) in the bottom-right corner. If it doesn’t, click the interpreter indicator again and pick the MicroPython entry for your board from the list.

Thonny's interpreter menu listing MicroPython options for the connected board, with one highlighted.
The interpreter menu after installing, now listing MicroPython for your connected board

Once Thonny shows MicroPython connected, move on to Project 1.3.