This page contains documentation for the SDU UAS TX, a DSMX based C2 transmitter developed by the SDU UAS Center. The transmitter has been designed for educational and prototyping activities.

Key features are:

• Based on the Arduino Nano.
• Compatible with the OrangeRX DSMX Transmitter module V1.2¹⁾ (and similar TX modules).
• Supports the open source CRRCSim²⁾ simulator via an audio jack connected to the computer microphone input.
• Other outputs from the Arduino: Piezo buzzer, red LED, green LED.
• Inputs: 2 joysticks, 2 two-pos switches, 2 three-pos switches, potentiometer, battery voltage.
• Optional serial input allowing transmission controlled by computer software.
• Open source hardware and open source software.

The SDU UAS TX it defaults to a transmitter output designed for use with the AutoQuad flight controllers.

If you wish to select a more generic output (tested with the CRRCsim simulator) please press down the left joystick and turn on the TX.

After calibration (see below) the TX will flash green 1 time for AutoQuad output or 2 times for CRRCsim output.

The SDU UAS TX firmware (see next section) requires calibration upon startup. Please follow this procedure:

After power-up the red LED will flash 2 times. Please move both joysticks to their extreme positions in both the horizontal and vertical orientation.

Having completed this it is time to save the extreme positions and the center position of the right joystick: Remove your thumb from the right joystick and press the left joystick down once. If the TX is happy about the calibration the red LED will now flash 1 time.

Now it is time to save the center position of the left joystick. Remove your thumb from the left joystick and press the right joystick down once. If the TX is happy about the calibration the green LED will now flash and the TX begins transmitting.

If the battery voltage is below 7.3 Volt the red LED will flash 1 time. If the battery voltage is below 7.0 Volt the red LED will flash 2 times. At this stage you should immediately stop using the TX and recharge the battery.

Firmware for the SDU UAS TX is available at:

• https://github.com/SDU-UAS-Center/SDU-UAS-TX

Schematics, PCB layout and Bill of materials are available in this document:

• http://frobomind.org/download/SDU_Transmitter_2018-03-23.pdf