Question about Changing SPI channel from SPI2 8Mhz to SPIM3 16MHz

[eleven-x_devteam]

Hi,

I am developing a custom device with nrf52840 and use SPI for flash driver and radar sensor.

For better SPI performance of the flash driver and radar sensor, I am trying to change the SPI channel from SPI2 8Mhz to SPIM3 16MHz since 16Mhz is only available on SPIM3.

The interesting thing is if I keep the SPI channel as SPI2 in bootloder and use SPIM3 in f/w application, that SPI communication in F/W doesn't work(no SPI clock in an oscilloscope).

When I update new BL with SPIM3 as well, SPIM3 in F/W works fine. I guess SPI setting in BL should not affect SPI in F/W.

Any clue about this problem?

[Jørgen Holmefjord]

Hi,

Are you using the same GPIO pins for the two SPI instances? Is the SPI peripheral uninitialized/stopped in the bootloader before the jump to the application is made? 

Can you provide an example that can be used to reproduce this behavior?

Best regards,
Jørgen

[eleven-x_devteam]

Right, using the same GPIOs for two SPI instances and doesn't have uninitializing code in the end of bootloader.

It makes sense that SPI2 is being used in bootlodaer and F/W will not be abled to initialize SPI3 with the same GPIO.

I verified that uninit SPI before jumnping to F/W can fix this issue.

Thank you!