Raspberry Pi Pico Flashing Guide¶

This comprehensive guide covers how to flash MicroPython firmware onto your Raspberry Pi Pico and upload your first program.

Table of Contents¶

Prerequisites
Understanding Raspberry Pi Pico
Method 1: Flashing with Thonny (Recommended)
Method 2: Manual Flashing
Uploading Your First Program
Setting Up Autostart
File Management
Common Issues

Prerequisites¶

Before you begin, make sure you have:

✅ Raspberry Pi Pico or Pico W
✅ Micro USB cable (data cable, not charging-only)
✅ Computer with USB port
✅ Thonny IDE installed (Installation Guide)
✅ Internet connection (to download firmware)

Understanding Raspberry Pi Pico¶

Raspberry Pi Pico Specifications¶

Feature	Specification
Microcontroller	RP2040 (Raspberry Pi custom chip)
CPU	Dual-core ARM Cortex-M0+ @ 133MHz
RAM	264KB SRAM
Flash Memory	2MB
GPIO Pins	26 multi-function pins
PWM Channels	16
ADC	3 channels, 12-bit
UART, SPI, I2C	Multiple interfaces
USB	1x USB 1.1 controller
Temperature Sensor	Built-in

Pico vs Pico W¶

Pico: Standard version without wireless
Pico W: Includes WiFi and Bluetooth (via Infineon CYW43439)

Boot Modes¶

The Pico has two boot modes:

BOOTSEL Mode (USB Mass Storage)
Appears as a USB drive
Used for flashing firmware
Accessed by holding BOOTSEL button while plugging in
Normal Mode (Running Code)
Executes uploaded MicroPython code
Regular operation mode

Method 1: Flashing with Thonny (Recommended)¶

This is the easiest method for beginners.

Step 1: Enter BOOTSEL Mode¶

Disconnect the Pico from your computer (if connected)
Locate the BOOTSEL button on the Pico (small white button near the USB port)
Press and hold the BOOTSEL button
While holding the button, connect the Pico to your computer via USB
Release the BOOTSEL button after 2 seconds

Result: The Pico appears as a USB drive named "RPI-RP2"

The BOOTSEL button is a small white button located near the USB port on the Pico board.

Step 2: Flash Firmware via Thonny¶

Launch Thonny IDE
Check Connection
The Pico should be detected as "RPI-RP2" drive
Install MicroPython Firmware
Click Tools → Options
Select the Interpreter tab
Choose "MicroPython (Raspberry Pi Pico)" or "MicroPython (Raspberry Pi Pico W)"
Click Install or update MicroPython
Configure Installation
Target volume: Select "RPI-RP2" drive
MicroPython variant:
- For Pico: "Raspberry Pi Pico / Pico H"
- For Pico W: "Raspberry Pi Pico W / Pico WH"
Version: Select the latest stable version
Click Install
Wait for Completion
Installation takes 10-30 seconds
Don't disconnect during installation
Pico will restart automatically
Verify Installation

After restart, Thonny's Shell should show:

MicroPython v1.x.x on YYYY-MM-DD; Raspberry Pi Pico with RP2040
Type "help()" for more information.
>>>

Test with Simple Code
```
>>> print("Hello, Pico!")
Hello, Pico!
```

Method 2: Manual Flashing¶

Advanced method for those who prefer manual control.

Step 1: Download MicroPython Firmware¶

Visit MicroPython Download Page
Go to https://micropython.org/download/
Select Your Device
For Pico: Raspberry Pi Pico
For Pico W: Raspberry Pi Pico W
Download Latest .UF2 File
Click on the latest stable release
Save the .uf2 file (e.g., rp2-pico-latest.uf2)

Step 2: Enter BOOTSEL Mode¶

Follow the same steps as Method 1, Step 1.

Step 3: Copy Firmware to Pico¶

Locate RPI-RP2 Drive
macOS: Check Finder sidebar
Windows: Check "This PC"
Linux: Usually mounted in /media/ or /mnt/
Copy UF2 File
Drag and drop the .uf2 file to the RPI-RP2 drive
Or use command line:

# macOS/Linux
cp rp2-pico-latest.uf2 /Volumes/RPI-RP2/

# Linux (adjust mount point)
cp rp2-pico-latest.uf2 /media/$USER/RPI-RP2/

# Windows (adjust drive letter)
copy rp2-pico-latest.uf2 D:\

Wait for Auto-Reset
The Pico will automatically reboot
RPI-RP2 drive will disappear
Flashing is complete!

Step 4: Verify in Thonny¶

Open Thonny
Go to Tools → Options → Interpreter
Select "MicroPython (Raspberry Pi Pico)"
Port should auto-detect
Click OK
Check Shell for MicroPython prompt >>>

Uploading Your First Program¶

Using Thonny¶

Create New File
Click File → New

Write Code

# blink.py - Simple LED blink example
import machine
import time

led = machine.Pin("LED", machine.Pin.OUT)

while True:
    led.toggle()
    time.sleep(0.5)

Save to Pico
Click File → Save as...
Select "Raspberry Pi Pico"
Name it blink.py
Click OK
Run the Program
Click the green Run button (F5)
Or click Run → Run current script
The LED should start blinking!
Stop the Program
Click the red Stop button
Or press Ctrl+C in the Shell

Setting Up Autostart¶

To make your program run automatically when the Pico powers on:

Method: Rename to main.py¶

Save or Rename Your Script
In Thonny, save your working script as main.py
Or rename existing file on Pico to main.py
Upload to Pico
Make sure main.py is saved to the Pico (not your computer)
Test Autostart
Disconnect the Pico from USB
Reconnect it (without holding BOOTSEL)
The program should start automatically

Example: Autostart Blink¶

# main.py - Autostart LED blink
import machine
import time

led = machine.Pin("LED", machine.Pin.OUT)

print("Autostart: LED blink program")
print("Press Ctrl+C to stop")

try:
    while True:
        led.toggle()
        time.sleep(0.5)
except KeyboardInterrupt:
    led.off()
    print("Program stopped")

To disable autostart: - Delete or rename main.py on the Pico - Or add a long delay at the start and interrupt with Ctrl+C

File Management¶

Viewing Files on Pico¶

In Thonny: 1. Click View → Files 2. You'll see two file browsers: - This computer: Your local files - Raspberry Pi Pico: Files on the Pico

Uploading Files¶

Drag and drop: - Drag files from "This computer" to "Raspberry Pi Pico"

Or use menu: - Right-click file in "This computer" - Select "Upload to /"

Downloading Files¶

Right-click file in "Raspberry Pi Pico"
Select "Download to..."
Choose destination on your computer

Deleting Files¶

Right-click file in "Raspberry Pi Pico"
Select "Delete"
Confirm deletion

Creating Directories¶

Right-click in "Raspberry Pi Pico" area
Select "New directory"
Enter directory name

Common Issues¶

Pico Not Detected¶

Symptoms: - RPI-RP2 drive doesn't appear - Thonny can't find Pico

Solutions: 1. Try a different USB cable (must be data cable, not charge-only) 2. Try a different USB port 3. Make sure you're holding BOOTSEL while connecting 4. Check Troubleshooting Guide

Upload Failed¶

Symptoms: - "Could not write to port" error - Upload hangs indefinitely

Solutions: 1. Reconnect the Pico 2. Restart Thonny 3. Check port permissions (Linux/macOS) 4. Re-flash MicroPython firmware

Code Runs Once Then Stops¶

Symptoms: - Program runs in Thonny but not on restart

Solutions: 1. Make sure file is saved as main.py 2. Check file is on Pico, not your computer 3. Add error handling to catch and print exceptions

Import Errors¶

Symptoms: - ImportError: no module named 'xxx'

Solutions: 1. Some modules are not available in MicroPython 2. Check MicroPython documentation 3. Use MicroPython-specific libraries

File Size Limitations¶

The Pico has 2MB of flash storage: - MicroPython firmware: ~500KB - Available for your code: ~1.5MB

Tips: - Keep code files small and modular - Delete unused files - Use .mpy compiled files for larger libraries

Next Steps¶

Now that you've flashed your Pico:

Try Example Scripts - Run the provided examples
src/pico_scripts/01_blink.py
src/pico_scripts/02_wifi_connect.py
Explore MicroPython - Learn the differences from standard Python
MicroPython Documentation
Build Projects - Try the seminar projects
WiFi signal monitor
API consumer
Access point web server

Additional Resources¶

Raspberry Pi Pico Getting Started: Official PDF Guide
MicroPython Forum: https://forum.micropython.org/
Raspberry Pi Forums: https://forums.raspberrypi.com/
Pico SDK Documentation: https://raspberrypi.github.io/pico-sdk-doxygen/

Troubleshooting¶

For more detailed troubleshooting, see the Troubleshooting Guide.