Unable to set P0.01 as a GPIO output

[hjklas]

As the title suggests, I am unable to set P0.01 as a gpio output. I know this pin is also used to source an external LFCLK, however I am using the internal RC clock.

I have the following defines in sdk_config

#define NRFX_CLOCK_CONFIG_LF_SRC 0
#define CLOCK_CONFIG_LF_SRC 0

#define NRF_SDH_CLOCK_LF_SRC 0

Also, I have made sure that NRF_CLOCK->LFCLKSRS is set to 0, yet I am still unable to toggle P0.01 as a gpio pin. 

Below is the code I am using to try and test this pin, it works for other pins just not P0.00 or P0.01.

uint16_t test_pin = NRF_GPIO_PIN_MAP(0, 1);
nrf_gpio_cfg_output(test_pin);
while(1)
{
     nrf_gpio_pin_toggle(test_pin);
     nrf_delay_ms(50);
}

P0.01 just stays low the whole time. Also, I am using the mbn52832 module dev kit with nrf sdk 16, schematic is here mbn52832_schematic.pdf (murata.com).

I have removed R46 and R45 and placed a 0 ohm resistor at R43 and R44 to ensure that the output pin is connected directly to the mcu.

Any insights into what the problem might be would be greatly appreciated,

Harrison

[Vidar Berg]

Hello,

It sounds like you have performed all the neccessary steps. That is, made sure the pins are routed to the pin header by moving the 0 ohm resistors, and made sure that the LF crystal oscillator was not enabled. Could you run to run the project or program the hex file below and see if it gives the same result? I verified that it worked on a nRF52 DK here.

blinky_pca10040_toggle_xl1_and_xl2.hex

blinky_use_xl_pins_as_gpio.zip

Thanks,

Vidar

[hjklas]

Hello Vidar,

I am seeing the same result after running your project. The XL1 and XL2 pins are staying low the whole time. There shouldn't be any other hardware changes besides moving the 0 ohm resistors correct?

Best,

Harrison Klas

[Vidar Berg]

Hello Harrison,

Strange. I looked over schematics again, and I don't see anything else that needs to be changed to route the XL IOs to the pin header. Only suggestion I can think of at this point is that you try to perform a continuity test to verify the connection.

Best,

Vidar

[hjklas]

I have performed continuity tests to ensure the connection from the resistor to the pin. There doesn't seem to be a way I can directly probe the output pin on the mcu. 

I can't think of anything else to test at this point, it seems like I have hit a dead end. 

[hmolesworth]

Perhaps have a look at the LFCLKSRC register; maybe it is not cleared correctly; both pins are either i/o or crystal, This is some code I posted a few years ago:

// Note 32kHz Osc pins can be both used as GPIOs or both used as 32kHz Crystal Oscillator
if ( (ThisPinId == PIN_NRF_XL2) && (NRF_CLOCK->LFCLKSRC & 0x000001) ) return "RTC-OSC-OUT";
if ( (ThisPinId == PIN_NRF_XL1) && (NRF_CLOCK->LFCLKSRC & 0x000001) ) return "RTC-OSC-IN";