Building a USB Vendor Device with the Raspberry Pi Pico

In this episode, I demonstrate how to create a custom USB vendor device using the Raspberry Pi Pico and the TinyUSB stack. We’ll look at a simple but complete example that implements both control and bulk transfers, following a subset of the protocol used by the xum1541 project (part of OpenCBM).

Building a USB Vendor Device with the Raspberry Pi Pico - Playing with the Pico ep1

This tutorial covers:

Setting up a basic USB vendor device
Implementing USB descriptors
Handling control and bulk transfers
Working with multiple cores on the Pico
Using the watchdog timer

Timestamps

00:00 Intro
01:19 What is a custom/vendor device?
02:27 Building & running the example
07:59 TinyUSB stack configuration
09:36 USB Descriptor code
15:46 Example header file
18:18 main.c
24:20 Control transfer callback
28:54 Bulk transfer callback
33:39 Wrap-up

The complete source code and documentation is available at:
https://github.com/piersfinlayson/tinyusb-vendor-example

This example is perfect for anyone wanting to:

Learn USB device development
Create custom USB peripherals
Understand low-level USB communication
Get started with the Raspberry Pi Pico

Prerequisites:

Basic familiarity with C programming
Raspberry Pi Pico
Development environment set up for Pico

Errata:

I implied that, if you run a watchdog on your Pico, you must start core 1, and feed the watchdog from that core as well as core 0. That’s not true - you only need to feed the watchdog from core 1 if you have started core 1 (which I am in this example for demonstration purposes).
The example may be incorrectly returning false from tud_vendor_control_xfer_cb() for transfers it doesn’t want to handle. It may be safest to return true for all unexpected/unhandled transfers.