Jared’s Status Report for Apr 18

The SPI bus is done. It operates at 15.6 MHz and transfers the data to and from the 50MHz domain successfully. The current protocol is as follows:

If the Pi receives a command:
Transfer a single byte (value 0x1).
Transfer the message length (size 4 bytes).
Transfer the message
Wait for single byte (value 0x1).
Read in the message length (size 4 bytes).
Read the message.
Transfer the message to the original sender.

The routine requires that every message has a response. A possible addition to this is a routine that attempts a short SPI read when receiving an empty message.

A recent change in design was made to use TCP over UDP. At the time I did not realize it, but the protocol does not interpret message fragmenting correctly. While we did not integrate in time to reach this state, I believe it would have caused issues on operation.

Leave a Reply

Your email address will not be published. Required fields are marked *