SPI loop-back test analysis

RE: SPI loop-back test analysis

Jakub Rzeszutko — Thu, 08 Mar 2018 07:41:05 GMT

Hi,

I just tested following example in SDK14.2: sdk\nrf5\examples\peripheral\spi

I have shorted only PINs: P0.04 (MOSI) and P0.28 (MISO).

Once trasnfer is done Rx buffer reflects Tx buffer.

RE: SPI loop-back test analysis

Ree Wang — Thu, 08 Mar 2018 05:24:01 GMT

Thanks!

RE: SPI loop-back test analysis

Jakub Rzeszutko — Wed, 07 Mar 2018 12:28:13 GMT

But this is not a problem. You can have 2 isntances of SPI on 1 DK 🙂

Nevertheless I will try to reproduce your case here. If I understand you correctly you have only SPI master and you have shorted MOSI with MISO?

RE: SPI loop-back test analysis

Ree Wang — Wed, 07 Mar 2018 12:22:02 GMT

Because I have only one DK, I want to do a loopback test...

RE: SPI loop-back test analysis

Jakub Rzeszutko — Wed, 07 Mar 2018 08:33:00 GMT

Hi,

Basically you need to configure 2 instances of SPI: 1 for master and 1 for slave and connect them:

- Master MOSI with Slave MISO

- Master MISO with Slave MOSI

- Master SCK with Slave SCK

- Master CS with Slave CS.

So you will need 4 connections - now you have only 1.

RE: SPI loop-back test analysis

Ree Wang — Wed, 07 Mar 2018 08:13:55 GMT

Thanks Jakub,

I didnt connect SCK. As I am doing loopback test, I thought both master and slave are the nRF52 DK. Therefore, I didn't connect SCK.

Could you tell me how to connect SCK for loopback test?

Regards

RE: SPI loop-back test analysis

Jakub Rzeszutko — Wed, 07 Mar 2018 07:25:30 GMT

Hi,
How did you configured SPI SCK? I assume master and slave shall have different PIN configured for SCK. I don't see SCK connection between SPI master and SPI slave on you picture.