SDK15.2 PCA10056 SPI example - change SCLK pin to 0.21

[Otso Jousimaa]

I'm trying to use Pin 0.21 as SCLK in the SDK15.2/examples/peripheral/spi/pca10056/blank/ses. 

The example works fine with CLK on pin 3 (default) and on pin 29 (just tried something else). However, on pin 21 I do not get any activity on CLK line - in fact the line seems to be floating judging by noise on oscilloscope trace. 

After testing a couple more pins it seems that I cannot use the CLK on pins which are connected to QSPI: 17, 18, 19,  20, 21, 22, 23 all fail, 16 and 24 work. 

I've tried the example on 2 different PCA10056 boards, one is 0.9.0 and one is 0.11.0 I'm compiling the project with SES 3.5.0 on Mac OSX.

Am I missing some configuration option or is this a hardware limitation?

[Marjeris Romero]

Hi,

Pins P0.17 and P0.19-P0.23 are by default connected to the 64 Mb external flash memory using QSPI. See the GPIO usage here. To use the GPIOs for another purpose and have them available in the P24 connector you need to cut six solder bridges (SB10-SB15) and six solder bridges must be shorted (SB20-SB25).

The solder bridge information is also printed on the back of the DK board.

Best Regards,

Marjeris