Cant drive pins with nrf_gpio_pin_setbut can using pullup/down.

[Jason]

Our new prototype uses an ISP1807 (nrf52840 module). The schematic is almost the same as a previous working prototype based on the Ublox Nina B302. (also nrf52840)

I've spent 2 days trying to understand what could be wrong and I'm not sure if this is a hardware or software problem. Or if my modules are somehow faulty. 

Using a brand new PCB that has had no other programming. 

• I can drive pin 6 (NRF_GPIO_PIN_MAP(0, 26)) high and low using nrf_gpio_pin_set(26); This is my RED_LED
• I can pull pins 2 and 4 high and low using the internal pullup / pulldown.
• I cannot drive pins 2 or 4 high using nrf_gpio_pin_set  (pins 2 and 4 are my SCL and SDA pins for my sensors)

#define MY_RED_LED_PIN                  NRF_GPIO_PIN_MAP(0, 26)   
#define MY_SCL_PIN                      NRF_GPIO_PIN_MAP(0, 10)
#define MY_SDA_PIN                      NRF_GPIO_PIN_MAP(0, 9)

This code 

    for (int ii = 0; ii < 10000; ii++)
    {
        nrf_gpio_cfg(MY_SCL_PIN, 
                      NRF_GPIO_PIN_DIR_OUTPUT,
                      NRF_GPIO_PIN_INPUT_DISCONNECT,
                      NRF_GPIO_PIN_PULLUP,
                      NRF_GPIO_PIN_S0S1,
                      NRF_GPIO_PIN_NOSENSE);

        nrf_delay_ms(300);

        nrf_gpio_cfg(MY_SCL_PIN, 
                      NRF_GPIO_PIN_DIR_OUTPUT,
                      NRF_GPIO_PIN_INPUT_DISCONNECT,
                      NRF_GPIO_PIN_NOPULL,
                      NRF_GPIO_PIN_S0S1,
                      NRF_GPIO_PIN_NOSENSE);

        nrf_delay_ms(300);

        nrf_gpio_cfg(MY_SCL_PIN, 
                      NRF_GPIO_PIN_DIR_OUTPUT,
                      NRF_GPIO_PIN_INPUT_DISCONNECT,
                      NRF_GPIO_PIN_PULLDOWN,
                      NRF_GPIO_PIN_S0S1,
                      NRF_GPIO_PIN_NOSENSE);

        nrf_delay_ms(300);
    }

Looks like this

But this code 

    nrf_gpio_cfg(MY_SCL_PIN, 
                  NRF_GPIO_PIN_DIR_OUTPUT,
                  NRF_GPIO_PIN_INPUT_DISCONNECT,
                  NRF_GPIO_PIN_NOPULL,
                  NRF_GPIO_PIN_S0S1,
                  NRF_GPIO_PIN_NOSENSE);

    for (int ii = 0; ii < 10000; ii++)
    {
        nrf_gpio_pin_set(MY_SCL_PIN);

        nrf_delay_ms(100);

        nrf_gpio_pin_clear(MY_SCL_PIN);

        nrf_delay_ms(100);

    }

Shows this

I can flash the LED using this code

          nrf_gpio_cfg(MY_RED_LED_PIN, 
                    NRF_GPIO_PIN_DIR_OUTPUT,
                    NRF_GPIO_PIN_INPUT_DISCONNECT,
                    NRF_GPIO_PIN_NOPULL,
                    NRF_GPIO_PIN_S0S1,
                    NRF_GPIO_PIN_NOSENSE);

          nrf_gpio_pin_set(MY_RED_LED_PIN);
          nrf_delay_ms(300);
          nrf_gpio_pin_clear(MY_RED_LED_PIN);
          nrf_delay_ms(300);

I've checked the datasheet for the ISP1807 and I cannot see anything special about those pins. I've looked at the product spec for the NRF52840 and I cannot see anything (but maybe I've missed something).

I cannot understand why I can pull the pin high with the internal pull up, but I cannot set it high with nrf_gpio_pin_set.

Any suggestions are greatly appreciated.

Pins 2,4, 6 are at the bottom of this image.

[Jørgen Holmefjord]

Hi,

P0.09 and P0.10 are by default used as pins for the NFCT peripheral. To use the pins as normal GPIOs, you either have to defined the preprocessor symbol CONFIG_NFCT_PINS_AS_GPIOS, as described in NFC antenna interface, or write zero to NRF_UICR->NFCPINS register.

You can check the state of the register by reading it with nrfjprog:

nrfjprog --memrd 0x1000120C
0x1000120C: FFFFFFFF                              |....|

And you can also write it:

nrfjprog --memwr 0x1000120C --val 0
Parsing parameters.
Writing.

nrfjprog --memrd 0x1000120C
0x1000120C: 00000000                              |....|

nrfjprog -r
Applying system reset.
Run.

Best regards,
Jørgen

[Jason]

oh wow. thank you!

[Jason]

FYI There's a mistake in the docs

I noticed this in the NFC doc section 

But on page it references there are no values. This is the latest NRF52840 product specification v1.2

[Jørgen Holmefjord]

Thank you for this notice, I have reported it internally. The parameter is included in nRF52832 specifications, but I'm not certain that it will be exactly the same for nRF52840 also.

[Jason]

Thanks, 10uA is a bit more than I expected but I've got pull-ups so there's probably no leakage across those pins. But you’ve reminded me that I really need to power profile ASAP (with my shiny new nordic power profiler 2!)

I’ve not had any problems using i2c with these pins. So the extra capacitance doesn’t seem to be a problem. The rest of the board was completely fine thankfully. 

I’m very grateful for your help with this. I had never considered the possibility that the pins were preconfigured in this way. I think it would be very helpful to add something to the GPIO section of the product specification.