Arduino code using the mbed core that runs on a Pi Pico (2040) to emulate a USB HID Joystick
Pirmarily developed to use and ExpressLRS receiver and a HID Joystick for Sim use!
Shout out to CapnBry for the Crsf Library
https://github.com/CapnBry/CRServoF
Shout out to RealRobots.net for the Gamepad Library
https://gitlab.com/realrobots/PicoGamepad/-/tree/master
Since FPVExchange is now down, please send me an email for availability, purchase, or to get additional info!
You can also contact me on discord HouseFPV
- Blank carrier boards for Pi Pico, Tiny 2040, and Waveshare RP2040
- Built and flashed units
This project was designed primarily with ELRS usage in mind, however this code base has also been tested with TBS Crossfire Receivers (915MHZ) (last tested v6.16) and TBS Tracer Receivers (2.4GHz) (last tested v6.17) and both appear to work! Flight was teseted in the Liftoff simulator.
I no longer have TBS Crossfire nor TBS Tracer TX modules or Receivers so future tests will have to be conducted by others.
Tested with arduino-1.8.19.
Go to Boards manager and install 'Arduino Mbed OS RP2040 Boards' package. I'm using version 2.6.1 currently.
Update the arduino ide preferences to point to the Sketchbook folder contained by this repo. Libraries and examples are already included.
Compile and upload.
On first upload to the pico, you will need to hold in the bootsel buttion before plugging it into the computer. This should only have to be done once and subsequent uppdates can be done automatically by the ide.
Once uploaded, the device should be recgonzed by your computer as a HID Joystick.
This was a quick map and is not fully featured.
On link up/down the onboard Pi Pico LED will light indicating connection
NOTE Channel 5, 6, 7, and 8 are mapped both to analog axis as well as joystick buttons.
| Channel | Logical Mapping | Joystick Mapping |
|---|---|---|
| 1 | A | X |
| 2 | E | Y |
| 3 | T | Rx |
| 4 | R | Ry |
| 5 | Channel 5 (Full) AND AUX1 (1510-2011) | Z AND Button 0 |
| 6 | Channel 6 (Full) AND AUX2 (1510-2011) | Rz AND Button 1 |
| 7 | Channel 7 (Full) AND AUX3 (1510-2011) | S0 AND Button 2 |
| 8 | Channel 8 (Full) AND AUX4 (1510-2001) | S1 AND Button 3 |
| 9 | AUX5 (1510-2011) | Button 4 |
| 10 | AUX6 (1510-2011) | Button 5 |
| 11 | AUX7 (1510-2011) | Button 6 |
| 12 | AUX8 (1510-2011) | Button 7 |
| 13 | Not Used | Not Used |
| 14 | Not Used | Not Used |
| 15 | LQ - Not Used | Not Used |
| 16 | RSSI - Not Used | Not Used |
Note additional button mappings can be created in caliration.h
| Part | Link | Approx Cost |
|---|---|---|
| Pi Pico | https://www.pishop.us/product/raspberry-pi-pico/ | $4 (Approx $6 with shipping) |
| Tiny 2040 (alt part) | https://www.pishop.us/product/tiny-2040/ | $10 (Approx $12 with shipping) |
| ELRS RX (any will do) | https://www.racedayquads.com/products/happymodel-2-4ghz-ep1-rx-express-lrs-receiver?_pos=1&_sid=c7214d987&_ss=r | $13.50 |
| https://www.amazon.com/dp/B07F7W91LC?psc=1&ref=ppx_yo2_dt_b_product_details | 10 for $7.50 ($0.75 ea) |
Approx part cost for pico hardware (large footprint, cheaper) - $20-$25
- Pi Pico - $4.00
- ELRS RX - $13.50
- Level Shifter - $0.75
- Carrier Board - $1.00 (approx)
- Shipping / Tax from vendors - varies
Approx part cost for tiny2040 hardware (much smaller footprint) - $25-$30
- Tiny2040 - $10.00
- ELRS RX - $13.50
- Level Shifter - $0.75
- Carrier Board - $1.00 (approx)
- Shipping / Tax from vendors - varies
NOTE: References to level shifters below are no longer needed as the level shifter can be omitted. You will have to bridge the pads on the level shifter for the TX/RX pins or use a newer version of the carrier board.
I personally use the Waveshare RP2040-Zero version for my ELRS Joystick!
Hardware build files are located in hardware/kicad/CRSFJoystick/output/Rev1.0
I used JLCPCB with Black Soldermask and a board thickness of 1.6mm.
Note the different orientation of the ELRS RX's. The orientation can be flipped. I installed each RX to ensure the boot pad is exposed should the RX need recovered.
Board files now in the hardware folder. Not built or tested but should work.
Build a smaller pico by yourself.
- Print the top and bottom enclosure
- Print 2 of the spacers for the Pi2040, Print 4 of the spacers for the Pi Pico version
- Follow the directions in this video https://youtu.be/Zuhfbobgm5A
- Convert from Arduino IDE to platform.io (or possibly QMK for more robust HID configuration)
- Add failsafe nopulses / hold
