Minimal example project for using TinyUSB with Pico-PIO-USB on a Raspberry Pi Pico

TinyUSB with Pico-PIO-USB can do bitbanged USB hosts/device on a Raspberry Pi Pico

The purpose of this repo is demonstrating a simple way to get the example code to compile as a separate project so check the CMakeLists.txt file.

The actual source code that is built isn't a part of this repo but comes from https://github.com/sekigon-gonnoc/Pico-PIO-USB.git (it is included in tinyusb https://github.com/hathach/tinyusb as a submodule under /hw/mcu/raspberry_pi/Pico-PIO-USB)

It isn't necessary to checkout tinyusb and pico-sdk as submodules if you already have them available, see below for details.

Requirements

Tools

• cmake
• arm-none-eabi-gcc

External Libraries (included as git submodules for convenience)

• tinyusb
• pico-sdk

Quickstart

# Checkout tinyusb & pico-sdk as git submodules
git submodule update --init -- tinyusb pico-sdk

# Checkout Pico-PIO-USB as git submodules in tinyusb
git -C tinyusb submodule update --init hw/mcu/raspberry_pi/Pico-PIO-USB

# Build
cmake -B _build && cmake --build _build/ --config Release

# Done
find _build/ -type f -name "*.uf2" -ls

Extras

Alternate variants

Copying the example code to ./src and build it there

1. Copy the whole host_hid_to_device_cdc folder to ./src
2. In ./src/host_hid_to_device_cdc/CMakeLists.txt comment out the line set(PICO_PIO_USB_SRC "${CMAKE_CURRENT_LIST_DIR}/../../src")
3. In ./CMakeLists.txt uncomment the line #set(SRC_TO_BUILD_PATH ${CMAKE_CURRENT_LIST_DIR}/src/host_hid_to_device_cdc)

# This performs the above steps
cp -R ./tinyusb/hw/mcu/raspberry_pi/Pico-PIO-USB/examples/host_hid_to_device_cdc ./src/
sed --in-place -re 's/^set\(PICO_PIO_USB_SRC .*/# \0/' src/host_hid_to_device_cdc/CMakeLists.txt
sed --in-place -re 's/^#(set\(SRC_TO_BUILD_PATH .*)/\1/' CMakeLists.txt

Build like usual:

cmake -B _build && cmake --build _build/ --config Release
find _build/ -type f -name "*.uf2" -ls

Overriding paths to pico-sdk and tinyusb

cmake -B _build -DPICO_SDK_PATH=$PWD/pico-sdk  -DPICO_TINYUSB_PATH=$PWD/tinyusb && cmake --build _build/ --config Release

Use branch "develop" of pico-sdk:

git submodule add -b develop https://github.com/raspberrypi/pico-sdk pico-sdk

GIT Submodule commands cheatsheet

# Checkout code
git submodule update --init -- tinyusb pico-sdk

# Checkout one submodule in a submodule
git -C tinyusb submodule update --init hw/mcu/raspberry_pi/Pico-PIO-USB

# Check status
git submodule status --recursive

Setting up your own project like this

Create empty git repo

git init barbaz
cd barbaz
mkdir src

Add tinyusb and pico-sdk as submodules

git submodule add https://github.com/hathach/tinyusb tinyusb
git submodule add https://github.com/raspberrypi/pico-sdk pico-sdk

Initialize the git submodule for Pico-PIO-USB included in ./tinyusb

git -C tinyusb submodule update --init hw/mcu/raspberry_pi/Pico-PIO-USB

Copy CMakeLists.txt from this repo

cp ../minimal-pico-tinyusb-pio-project/CMakeLists.txt ./

Build

cmake -B _build
cmake --build _build/ --config Release
find _build/ -type f -name "*.uf2" -ls