# SmartPort (SPort) Master
## Overview
With the Taranis, I got a GPS using the “SmartPort” interface from FrSky. It's basically a Serial bus on which you can add many sensors, which are (randomly ?) polled by the master of the bus.
* One wire bus ( ⇒ Half Duplex communication ) * Inverted logic * 57600 bauds
Luckily the Teensy3 can do that. If you don't want to mess with voltage conversion, just use a Teensy3.1.
Most of the information comes from the OpenTX firmware, information on the Internet and direct analysis of the communication bus, so it might not be perfectly accurate.
## Teensy3
I don't have anything permanent, it's all on breadboard for now, so there's no schematic. Just connect the signal pin of the sensor to the pin 1 of the Teensy (TX1, PB17), Gnd to Gnd and… you're done. You can power the GPS using the Vin pin of the Teensy, it makes development easier.
Here's the last code: tsysportmaster_20140916.tar.gz
<note important>This is experimental work. Do this at your own risks.</note>
## Next ?
* Forge UBX/NMEA packets from SPort GPS data
* Serial/SPI/I2C output (something standard 
)
* Write a TauLabs module, like the existing one for the Hub Telemetry
* Attiny(25/45, or 85 but it might be overkill) port with serial output, with Low power mode so it can be embedded on virtually any other flight controller
* Support more sensors
## Links
I found different projects interfacing the Teensy3.1 with a SmartPort receiver (like the X8R):
* http://code.google.com/p/telemetry-convert/ * https://code.google.com/p/telemetry-convert/wiki/FrSkySPortProtocol * http://diydrones.com/forum/topics/amp-to-frsky-x8r-sport-converter