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Serial Outputs for 2.4GHz Receivers

My DSM2 compatible 2.4ghz receivers can output serial data streams on one pin, usually used for quadcopter type models, UAV's etc. Two types are available, Serial and Sequential PPM.


- 16 byte RS-232 serial output at 115200 baud, 8 bit, no parity, 2 stop bits, LSB first.
- Byte 1: Checksum - sum of other 15 bytes cast to 1 byte
- Byte 2: Signal quality - 1st bit (MSB) 1=new data, 0='hold' data/signal not validated; next 2 bits not used; last 5 bits (LSB) = RSSI (31 max, 0=no signal/timeout)
- Bytes 3-16: Payload - 7 channels, 2 bytes per channel - 1st 3 bits not used, next 3 bits = channel number, last 10 bits = servo position
- Frame rate is 22ms


- 7 channels ~0.9 to 2.1ms, 1.5ms neutral
- 300us start/stop pulses; either edge can be used for triggering
- 'v3 software only has fixed numeric sort order (0-Throttle, 1-Aileron, 2-Elevator, 3-Rudder, 4-Gear, 5-Aux1, 6-Aux2)
- 'v2' software has options for fixed numeric and for the order to be as supplied by the Tx
- Frame rate is 22ms

More information on 2.4GHz can be found here:
* DSM2 compatible receivers
* Overview of 2.4GHz
* 2.4GHz scanner
* 2.4GHz range tests
* Spektrum technical FAQs
* QFN soldering

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