The purpose of the sub-hub is in order that arbitrary electronics can be put in the wing of a plane with 2 piece or more detachable wings while being able to connect the wing to the fuselage with a single 4 way connector for useability.
The sub-hub communicates with the FC via a high speed uart. The connector also provides power at 7 to 20 V. (There is a switching regulator on the pcb to convert this to 5V at 2 A for the servos.
The prototype PCB uses an stm32f0 as the mcu and has the following features:
* 2 servo PWM outputs which can provide 2A at 5V. ( More coud be added as necessary but I only need 2 servos on the current project)
* analog /digital RSSI input from the RcRx
* PPMsum receiver input from RcRx
* FrSky telemetry output to th RcRx
* UART (for GPS)
* Other analog input ( for airspeed sensor)
* I2C input (for magnetometer.- airspeed etc)
I'm assuming I can get a baud rate of 1 Mbit per sec over the link ( cable length is around 400 mm) , so the next task is to try to work out the detail of communication between a sub-hub and the FC.
The UART for comm with the FC is probably an overly simplistic way of doing things. Dependent on how this goes, I may try a UAVCAN version or even a USB version using an Raspberry Pi as the host