MPC5775B DSPI baud rate setting with slew rate control and drive strength

[MarkFan]

Hi, 

     I use DSPI to connect FRAM device, default setting is 2Mhz slew rate control and half drive strength,

     it's working fine, however, I tried to increase the  baud rate to 40Mhz , I got error. then I tried some different setting and result as below,

1. 25-40Mhz, CLK/MOSI/MISO without slew rate control and full drive strength - OK

2. 2-5MHz, CLK/MOSI/MISO with slew rate control and half drive strength - OK

My questions are.

1. baud rate to 40Mhz but measure the clock = 25Mhz? 

2. How can I setting the baud rate I want from 2Mhz - 40Mhz without no error.

Thanks for any help.

Mark

[davidtosenovjan]

Full drive strength with slew control disabled (SIU_PCRn[SRC] = 11b) is the configuration with fastest edges, so it is needed to use for higher frequency setting.

For higher frequencies you can also use Modified SPI/DSI Transfer Format.