This high-precision altimeter/variometer is designed to work with Team Black Sheep's Crossfire and Tracer PWM receivers, and should also work great with any RC receivers that are able to speak the CRSF protocol at 416,666 baud, and transmitters that can receive and display it.

Note: This product is unrelated to the UDB7mini, and is meant for gliders/planes without a full flight controller.

How It Works

It uses an MS5607 barometer to convert pressure to altitude. It sends CRSF messages to your transmitter for both Altitude and Vertical Speed (Vario).

Since pressure changes with the weather, it is recommended to zero-out the altitude value on your transmitter on every launch, and then view the relative altitude during the flight.

Setup Guide

• Wiring: Solder a short servo cable to the 3 pads. Square pad is Ground(-), then VCC(+3V to +6V), then Data.
• Power Pass-through (Optional): Connect your Receiver's battery to the 2 additional pins for power and ground, if you want to avoid plugging your battery directly into your radio receiver, or it's out of power pins.
• Installation: Cover the barometer chip to prevent light leaks, but ensure air circulation.
• Radio Config: Set up your receiver's Output Map (e.g., 3 & 4) as CRSF RX and CRSF TX. Connect the altimeter to the CRSF RX channel's pins, and note that the receiver's Mavlink TX channel is not used.
  Then power up your plane and transmitter, and tell your transmitter to Discover New Sensors. It should find a few new sensors, and the ones you want to use are "ALT" and "VSpd".
  Then use these values however you want! I set up my transmitter's Discus Launch Glider model to speak the Alt sensor value 3 seconds after each launch, to get instant feedback on how high my launches are going, and I set up the Transmitter's Variometer settings to watch the VSpd sensor to beep when I'm in rising or sinking air.