SPI Slave CLK

Question

Hi 
 I'm using two different designs using nRF51822 as SPI Slave.
One is using p0.07 as CLK input and the other is using p0.06 as CLK input.
I'm using the code from spi_slave.c/h without any changes. 
 The one using p0.07 works like a charm. 
 Using p0.06 adds a 90Mhz oscillating signal to the clock-pulses and consequently the SPI Slave doesn't understand it. 
 Are there any default-settings on p0.06 I have to shut off?
I'm not using any analog stuff whatsoever.

Stefan Birnir Sverrisson · Accepted Answer

I am not able to reproduce the problem on my side with the standard spi_slave_example from the SDK and the spi_master_example_with_spi_slave. 
 You say you change port which gives the same result, what port exactly? Do you change port on the PCA10001 or your custom board? 
 Where is the SPI slave located? On your custom board or on the PCA10001 board? 
 What frequency is selected for the SPI? 
 I suspect there is something on your custom board that is creating this disturbance. Perhaps you could show us your schematics and layout for your custom board, in case we see something suspicious. For that purpose, create a support case in our support portal on www.nordicsemi.no. Go to the bottom of the page and click Technical Support Team. Attach your schematics with your case and refer to this thread. 
 Any additional description of the problem would be helpful. Images from your scope that show the disturbance signal would be appreciated.