how to config p21 as a gpio

RE: how to config p21 as a gpio

FormerMember — Thu, 12 May 2016 04:08:00 GMT

ok! it is solved after erase all with nrfgo, thanks!

RE: how to config p21 as a gpio

RK — Thu, 12 May 2016 04:03:03 GMT

That's what I said, you need to erase the UICR which will reset it back to 0xffffffff. Just perform a full erase on the chip with whatever tools you're using, and then reload the softdevice and your code. As long as you no-longer have that #define, it won't replace the value back to 0x15 when you run and the pin will work as normal. if it does put it back, you still have the define defined.

Note also that P0.21 is connected to the debug in, so if (unlikely) you are using an external debugger, it may hold that pin high. Looking at the schematic, I believe that is not the case as long as you are using the on-board debugger, which you probably are.

RE: how to config p21 as a gpio

FormerMember — Thu, 12 May 2016 03:59:13 GMT

ok, if value of NRF_UICR->PSELRESET[0] and NRF_UICR->PSELRESET[1] should be reset to 0xffffffff, now it is 0x15

RE: how to config p21 as a gpio

RK — Thu, 12 May 2016 03:52:22 GMT

... and .. is that a question? Have you ensured the UICR has been erased or not? Have you checked the reset pin configuration in the UICR to make sure it's not configured as a reset pin? If it was ever configured as one, it will stay configured as one.

RE: how to config p21 as a gpio

FormerMember — Thu, 12 May 2016 03:49:37 GMT

I just test with sdk example: nRF5_SDK_11.0.0_89a8197\examples\peripheral\spi\pca10040, just modified the spi io config

RE: how to config p21 as a gpio

RK — Thu, 12 May 2016 03:27:54 GMT

Then P0.21 should work just like any other GPIO. Make sure you've cleared the UICR entirely as if you've ever run with that define set, the pin has been configured as reset and that configuration is sticky (it is't in non-volatile memory)

RE: how to config p21 as a gpio

FormerMember — Thu, 12 May 2016 03:22:49 GMT

I have removed this define

RE: how to config p21 as a gpio

RK — Thu, 12 May 2016 03:20:57 GMT

have you defined P0.21 as the reset pin with CONFIG_GPIO_AS_PINRESET

RE: how to config p21 as a gpio

FormerMember — Thu, 12 May 2016 03:16:21 GMT

it is 52, I configured p21 as spi clk but it is not work, it is ok when I change to another io.

RE: how to config p21 as a gpio

RK — Thu, 12 May 2016 03:12:42 GMT

That's not a very clear question is it

nrf51 or nrf52?
What have you tried? Post code.
What problem are you actually having if you have tried something.

you configure P0.21 as a gpio just like you configure any other pin as a gpio.