I try to communicate by SPI between MSP430F6779 and F28035. MSP is a master, and F28035 is slave. The problem is, F28035 has 16-bit SPI register but MSP has 8-bit. I try to send 2 8-bit commands and read it as one command on F28035. I emulate SS pin by another GPIO, so SS will not go to high state between bytes. Unfortunately, some data is not read properly. We are sending alternately following data: 0x1000 and 0x1001 ( For MSP430 that is two commands like 0x10 and 0x00). We receive appropriate data in around 75%. Most of the wrong data are read as 0x8001 or 0x0801 or 0x0401 so one or two bit are shifted. Between two signals, there is a gap when clock is not generated, is it a problem? I try to change clock phase and polarity on slave and it did not help. I try to send in various frequencies, and it also did not improve much.
I am sending oscilogram. Yellow is SS, Pink is clock and blue is MISO.
Slave is probably good configured. I try to send from one F28035 to another F28035 and it works good.
