Hub should communicate via UART to DX810

[gillspice]

Message info for communicating to DX810:
UART, 115200 baud rate

Message Format
All messages consist of the following fields (each field is a single byte):
Sync, Device ID, Message ID, Effect ID, Channel, Index, Value

For setting crosspoint gain:
Sync: A5
Device ID: 00
Message ID: 78
Effect ID: 04
Channel: Output channel (1-10), determined by the ID of the transmitter
Index: Input Channel (1-8), determined by the pot number
Value: 8-bit value (0xFF) = + 10 dB, 193 (0xC1) = 0 dB, 0 = off