Concurrent device access causes interference between programs

Created by: Lekensteyn

When I tried to run scan-registers.sh while solar was running, it tagges wrong messages as a response to another (solar periodically reads the battery register 07).

Part of the solution:

• Use the following hints to match responses and requests:
  • the device index, type and register.
  • in case type=ERROR_MSG (8F), compare the device index and the Sub ID plus register of the error message to the request.
• Let messages be asynchronous (in a dedicated I/O thread?), on submission it will be queued. A queue item could have the attributes time of submission (for expirity), a callback function and the actual message.