Writing to Multiple SPI Devices in Parallel

RE: Writing to Multiple SPI Devices in Parallel

haakonsh — Fri, 01 Oct 2021 10:02:43 GMT

The driver can't write in parallel but the HAL can with the aid of the PPI and EGU.

The idea is to intitialize the SPIM's and their buffers, and then trigger the TASKS_START in all SPIM's at the same time via the PPI system.

In order to trigger 2 tasks from one SW call you need to use the EGU — Event generator unit to generate a PPI event, this PPI event can then be 'forked' to the two SPIM's START tasks.

RE: Writing to Multiple SPI Devices in Parallel

Omer Farooq — Mon, 27 Sep 2021 12:05:30 GMT

Hi Haakonsh,

Can you please comment on the following, as the link you shared doesn't explicitly states something w.r.t. my problem.

Thanks. Let's take an example. We suppose that I have two devices A and B. I want to connect A on SPI interface 1 and B to SPI interface 2. I want to write 0x01 to A and 0x02 to B in parallel. From your reply it seems that I can't do it in parallel, rather what I can do is to call nrfx_spim_xfer device twice first with data buffer containing value 0x01 and then call it again with data buffer containing value 0x02. This means we can only do sequential write and parallel writes are not possible in this case?

Best regards,

Omer

RE: Writing to Multiple SPI Devices in Parallel

haakonsh — Mon, 27 Sep 2021 11:56:22 GMT

See SPIM API docs and SPIM — Serial peripheral interface master with EasyDMA technical specification.

RE: Writing to Multiple SPI Devices in Parallel

Omer Farooq — Mon, 27 Sep 2021 11:14:01 GMT

Best regards,

Omer

RE: Writing to Multiple SPI Devices in Parallel

Turbo J — Mon, 27 Sep 2021 10:51:54 GMT

No but you can call this function multiple times and thus let it run in parallel. API is on the infocenter.

RE: Writing to Multiple SPI Devices in Parallel

Omer Farooq — Mon, 27 Sep 2021 10:34:58 GMT

One more thing can nrfx_spim_xfer() in parallel write different data to different SPI instances? Please also point me to the API documentation.

RE: Writing to Multiple SPI Devices in Parallel

Omer Farooq — Mon, 27 Sep 2021 10:10:14 GMT

Can you please share the documentation of nrfx_spim APIs?

RE: Writing to Multiple SPI Devices in Parallel

Turbo J — Mon, 27 Sep 2021 10:06:59 GMT

One idea is to use nrfx_spim_xfer() in non-blocking mode.