SPI frequency limit

[vn2000]

In the nrf_drv_spi_frequency_t; structure, the maximum SPI frequency I can set is 8MHz, while many new SPI devices run at a higher speed.

The device I'm using can run up to 50MHz. But at this moment I'm limited to 8MHz due to that firmware structure. I'm using the nRF52840 kit with SDK V17.

I think there must be a way to write to some register a value in order to change the SPI frequency. I will be happy to do this in order to improve my firmware performance.

Please can someone give any suggestions? Thanks.

[Kenneth]

Hello,

Try using SPIM3 (SPIM0-SPIM2 only support 8MHz and below), while SPIM3 support up to 32MHz:
https://infocenter.nordicsemi.com/topic/ps_nrf52840/spim.html#topic

Kenneth

[vn2000]

I was able to locate a SPIM3 example here:

SPIM3 on nRF52840 and SDK17.0.2 - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

I downloaded ble_test_spim3.zip and compiled it. But I got the error 'undefined reference to nrfx_spim_init'.

What I don't understand is that I have 'I#define NRFX_SPIM_ENABLED 1' in sdk_config.h, but in nrfx_spim.c everything is grayed out after the line:

#if NRFX_CHECK(NRFX_SPIM_ENABLED)

Therefore nrfx_spim_init is undefined.

[Kenneth]

Can you share you sdk_config.h file?

Kenneth

[vn2000]

3652.sdk_config.h

[vn2000]

Enclosed please find the file sdk_config.h

[Kenneth]

The case you link to says that you should comment out SPI_ENABLED, so for instance:

//#ifndef SPI_ENABLED
//#define SPI_ENABLED 0
//#endif

Please do so.
 
Kenneth

[vn2000]

Hi Kenneth,

I never thought we have to do that. However, the problem is fixed and now I can compile it.

Thank you for your help.