SPI share problem

RE: SPI share problem

Susheel Nuguru — Thu, 28 Jun 2018 12:04:05 GMT

Like Ketil mentioned, the way you do is not common. Normally you use CS pin to address slaves.

At the same time, what you are doing is not illegal operation. It is hard to say why nrf_drv_spi_transfer stops. But are you not able to start your code in the debug mode and see where exactly it is stuck in this function and why?

RE: SPI share problem

Bing — Thu, 28 Jun 2018 09:35:51 GMT

Hi ketiljo, the hardware are already designed and cannot be changed. And the two spi devices do not share any pins, I have to reconfig the SPI0 before each communication start. So I want to know is there any same usage scenarios examples. Or anyone else had the same problem as me?

RE: SPI share problem

ketiljo — Thu, 28 Jun 2018 09:26:34 GMT

If you route MISO, MOSI and CLK to both devices and use separate CS (chip select) pins, you don't need to reconfig the SPI pins at all.

RE: SPI share problem

Bing — Thu, 28 Jun 2018 06:14:46 GMT

Sorry, I give the wrong description of my problem. In fact, not the nrf_drv_spi_init() gives the failed error code. But the communication always stops to wait for the current transmission issued by api nrf_drv_spi_transfer() to be complete. It seems that the freuquently uinit and init SPI0 causes the problem. All the SPI0 communications start and done is in the event handler registered by app_sched_event_put(). The using SDK is version 11.0.

RE: SPI share problem

Susheel Nuguru — Wed, 27 Jun 2018 20:29:34 GMT

what error does it give? does it give NRFX_ERROR_INVALID_STATE? If so, then the uninit was not successful for some reason. I cannot see any other reason for the _init to fail

RE: SPI share problem

Bing — Wed, 27 Jun 2018 14:29:52 GMT

Thanks. I know what is SPI. My problem is I need to reconfig the spi pins(miso, mosi, sck) before a new communication start. When I do this, the nrf_drv_spi_init() return a error code not NRF_SUCCESS.

RE: SPI share problem

ketiljo — Wed, 27 Jun 2018 14:17:39 GMT

This it not how you should use SPI. It's designed to support multiple slaves. Have a look at this http://www.circuitbasics.com/basics-of-the-spi-communication-protocol/

Use one GPIO as select pin for each slave.