Sparse documentation of TASKS_SUSPEND and TASKS_RESUME in the SPIM with Easy DMA section of the nRF52832 data sheet

[David Anthony]

There seems to be little documentation on TASKS_SUSPEND and TASKS_RESUME in the SPIM with Easy DMA section of the nRF52832 data sheet. My assumption is that TASKS_SUSPEND stops the clock signal during an SPI transfer and TASKS_RESUME resumes the clock signal. Is this correct ?

[Kenneth]

It doesn't seem as the Figure in the documentation show the suspend and resume tasks, but there is a description in the text:
https://www.nordicsemi.com/DocLib/Content/Product_Spec/nRF52840/latest/spim?733#concept_lhv_fx2_wr 

"A transaction can be suspended and resumed using the SUSPEND and RESUME tasks, receptively. When the SUSPEND task is triggered the SPI master will complete transmitting and receiving the current ongoing byte before it is suspended."

So when calling SUSPEND task the clock is stopped after the ongoing byte is finished, the clock is started again when RESUME task is called.

Edit: I notice I referred to the nRF52840 datasheet, but the same applies to the nRF52832.

[David Anthony]

Is there an event associated with the completion of the transmission and receipt of the ongoing byte when the SUSPEND task is used ?

Looking at the nRF52832 data sheet it appears there is not.

[Kenneth]

No there is not. So you may consider add a nrf_delay_us(8); after calling SUSPEND task if you are using 1Mbps to ensure that ongoing byte is suspended.

Best regards,
Kenneth