Modbus: deciphering the CRC protocol

The Modbus over Serial protocol doc has a clear, simple set of instructions on how to decode. You just have to know that two of the steps are in a reverse order, but it actually makes sense. The Modbus protocol is used by the Daybetter LED light Bluetooth protocol. It's arguably a terrible fit for this: the protocol includes a bunch of stuff that isn't even slightly relevant with Bluetooth (like…