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:<\/p>\n
If the Pi receives a command:
\nTransfer a single byte (value 0x1).
\nTransfer the message length (size 4 bytes).
\nTransfer the message
\nWait for single byte (value 0x1).
\nRead in the message length (size 4 bytes).
\nRead the message.
\nTransfer the message to the original sender.<\/p>\n
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.<\/p>\n
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.<\/p>\n","protected":false},"excerpt":{"rendered":"
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). … <\/p>\n