4.2.8 Maximum UART Command/Response Frame Size

The maximum command and response data payload sizes are client dependent. The MaxCommandDataLength parameter defines the maximum number of bytes contained in the command data payload. See Command-Response Pairs for more information on command and response sizes.

The figure below shows the maximum size of a command and response.

The UART transport layer adds on a 2-byte checksum to commands and responses as shown in the figure below.

The worst case scenario is if every byte in the command or response is equal to a reserved code and has to be replaced with a 2-byte substitution in the expanded command/response and checksum as shown in the figure below.

Finally, the Start-Of-Frame and End-Of-Frame codes are added to the MDFU UART command/response frames. This results in a final formula for the worst case maximum size MDFU UART command frames and response frames.