The Falcon boards use generic +3.3V serial ports, however to connect to certain manufacturers’ devices, it is necessary to use external interface boards. On the current Falcon 1 and 2 Rev 1.0 boards, external interfaces are required for SBUS receievers, FrSky S-PORT telemetry and Minim/Micro Minim OSD.
The interface boards detailed below use easily obtainable electronic parts, to facilitate anyone who is interested in creating and soldering the boards themselves. However, a plug and play interface kit will be available in early September (2017).
The SBUS standard reverses the polarity of a standard serial port signal. The Falcon Rev 1.0 boards therefore require a special, external, +3.3V compatible SBUS inverter circuit shown below:
The flight controller connector is attached to the Falcon’s throttle channel, while the receiver’s goes to the SBUS channel.
FrSky S-PORT Telemetry (Falcon 2 Only)
Some FrSky receivers use Smart Port (S-Port) telemetry to allow the flight controller to return flight data back to the transmitter.
Transmitters such as the Taranis X9D allow alarms to be set, for instance for low battery level or maximum altitude.
Note: either on menu pages where the OLED display is being continously refreshed, for example in SAFE mode, or when the GPS is active such as the loiter and RTL flight modes, the Falcon 2 is currently unable to meet the S-Port telemetry’s specific timing requirements. In this situation S-Port telemetry doesn’t fail, but the simply drops out. Switching to static menu pages or other flight modes causes the telemetry to recover oncemore.
The flight controller connector is attached to the Falcon 2’s central Serial2 port, while the single wire connects to the receiver’s S-Port connection. Note that the receiver’s ground is provided by the main (CPPM or SBUS) connector.
Minim/Micro Minim OSD
To interface the Falcon boards to a Minim or Micro Minim OSD requires a simple I2C Level Shifter. The level shifter is required to protect the Falcon 1 and 2’s +3.3V output, from the the +5V OSD receiver pin during start-up.
The cables for either side of the interface are as follows:
Falcon to I2C Level Shifter
I2C Level Shifter to Minim/Micro Minim OSD