MSPM0L1306: 32-bit data SPI frame size with MSPM0 L-Series MCU

• By enabling the PACKEN feature, the SPI module will combine multiple smaller data frames (e.g., two 16-bit frames) into a larger packet.

• Set the SPI data frame size to 16 bits, which is the maximum supported frame size in this case.

•  When you send data, the SPI module will automatically pack the data frames into larger packets. For instance, if you need to send a 32-bit data frame, you would send two 16-bit frames consecutively.

• With PACKEN enabled, the CS signal will remain asserted (active) across the entire transfer of the packed data. This means the CS signal will not toggle between the 16-bit frames, effectively treating the two 16-bit frames as a single 32-bit frame from the perspective of the CS signal.

Hello Zain, good day.

Thank you for the detailed explanation and recommendation.

The approach that you are describing makes sense to me; I will implement this method and test it. Once I have proven that it, in fact, works; I may share the example and resolve this question.

Best Regards.

You can also use 3 wire mode and control CS yourself.

Hello again.

I have been working on implementing the suggested steps by Zain.

I am able to see the individual 16-bit data frames. But it appears that the packing feature with the PACKEN = 1 is not working as described in the documentation for the MSPM0 L-Series of MCU.

While using the debugger features of CCS, I have tracked down the issue to what seems to be related to writing to the TXDATA register of the SPI module.

The documentation (Technical Reference Manual, doc # slau847d) shows that this is a 32-bit register.

However when I write a 32-bit value (uint32_t) using the API function calls DL_SPI_transmitDataBlocking32() or even the basic DL_SPI_transmitData32(), what I observe is that only the lower 16-bits of the TXDATA register change while the upper 16-bits remain at zero. This results in only a single 16-bit entry moving to the FIFO, then followed by the 16-bit data frame going out the PICO port. The chip select is only remains active while the 16-bit are transferred out.

Is there something in the API that truncates the 32-bit value before it gets written to the TXDATA registers since the maximum frame size supported is 16 bits?

Kind Regards.