SLAA638A august 2014 – may 2023 MSP430I2040 , MSP430I2041
Figure 7-2 and Figure 7-3 shows the structure of the command and respond frame in polling mode. The command and respond frame has the same structure in the header and the frame end, the difference is in the data field. The first 2 bytes in the data field of a command are CMDH and CMDL, which defines the command and the parameters that follows. After receiving a valid command frame from the host, the EVM responds to the host with a respond frame with the RSPH = CMDH and RSPL = CMDL | 0x80 (because of that CMDL cannot use value larger than 0x7F). The respond data is defined by the command received.
The definition of commands and the corresponding response are listed in the next section.
When writing custom protocol, make sure that the data buffer is sufficient to hold the data byte from the host