normbxl/usb_ppm_joystick

Arduino adapter for RC remote control PPM signal to USB HID Joystick

USB PPM Joystick

An Arduino adapter for RC remote control PPM signals to USB HID Joystick.

Many (semi) professionl remote controls can output their control signal via a connector. Usualy the signal is PPM modulated.

If you want to train your steering skills before lifting off your RC helicopter you should consider using a RC simulator first. With this adapter-sketch you can use your original remote control as an joystick.

This sketch uses a slightly modified version of the vusb library in order to work with the Arduino framework, added some const before PROGMEM and changed the typedef of byte to uchar. The sketch is based on the UsbJoystick demo from Michel Gutlich (example included in library).

Requirements

Arduino IDE >1.0

Installation

You need to move the folder UsbJoystick to your sketchbook's libraries folder!

Hardware

This has only been tested with boards based on the Atmega168 MCU (Arduino Duemilanove). It should work with Atmega328 boards (Arduino Uno) as well.

The electric scheme included does not show all the Arduino connections and additions. It just shows a kind of bare minimum required. The voltage regulator is only required because USB signals are 3.3 V based while the USB power is 5 V.

Connections

Arduino D2 -> USB D+ (fixed)
Arduino D3 -> USB D- (fixed)
Arduino D4 -> 1.5 kOhm -> USB D- (optional)
Arduino D8 -> PPM input (changeable in code)

usb_ppm_joystick's Issues

Working after inverting my PPM signal

My config: Radiolink T8S transmitter and R8EF receiver, in PPM mode (blue LED means SBUS on ch1, PPM on ch2). Receiver powered from 5v USB, but its signal outputs are natively 3.3v, so that's nice.

I'm using an Arduino Uno, which is a mega328p. It enumerates on USB just fine, but I coudn't get any change in the readings when I moved the sticks.

Finally, I compared the oscilloscope trace of my PPM signal with some other images I found online, and... it appears to be inverted? So I grabbed the first NPN transistor I could find, a big ol' TIP31, and made a simple inverter. Et voila, suddenly it works! Joysticks wiggle, simulators simulate!

I'm pretty sure I could swap a bunch of HIGHs and LOWs in the code and do the same thing, but I'm more confident with transistors than code. ;)

I'm getting Unrecognized Device

I'm using a 5V, 16mHz Arduino Pro Mini with Atmel 328p powered by 3.3V through an AMS1117 voltage converter. I uploaded the sketch using a CP2102 USB to UART converter without errors.
When I connect the device to my Win7 laptop USB slot, I get "Unrecognized Device". I tried changing D+ with D- but that was not the problem. Your help would be very much appreciated.

positive or negative PPM supported?

Hi,

I tried to use this adapter on an old Graupner mc15. The HID device is recocnized properly at the PC but no axis is giving any movement. A PPM sigfnal is present at pin8.
Is a positive or negative signal required at pin8 or is there any software possibility to "invert" the signal?

Thanks for this nice project anyway.

Onki