GPIO PIN issue

RE: GPIO PIN issue

Jørgen Holmefjord — Wed, 24 Oct 2018 09:38:21 GMT

Why are you writing the whole OUT register? If you are doing this, I would recommend that you use OUTSET and OUTCLR.

With that said, what I would recommend the most is to use the GPIO HAL functions to configure, set and clear pins:

Best regards,
Jørgen

RE: GPIO PIN issue

hmolesworth — Tue, 23 Oct 2018 21:30:26 GMT

The code you listed above in the first question shows "&=" (a read-modify-write operation) and not "=" (a write operation). Yes just "=" 0xFFFFFFFF should indeed set them all high, which is what I was trying to say.. sorry if I was just confusing. It may be that nrf_gpio_cfg_output() just expects a pin number, eg 6, and not the value you are passing. See this example:

//      Software Label  Id // Pin Name  Dir Function  Description
//      =============== == // === ===== === ========= ===========
#define LED_GREEN_PIN   30 //  29 P0.30 Out GPIO/AIN6 LED_GREEN

    //                 Pin Id                Pin Port Schematic
    //                 ===============       === ==== =========
    nrf_gpio_pin_set  (LED_GREEN_PIN   ); // 29 P0.30 LED_GREEN
    nrf_gpio_cfg(LED_GREEN_PIN,           // 29 P0.30 LED_GREEN
                 NRF_GPIO_PIN_DIR_OUTPUT,
                 NRF_GPIO_PIN_INPUT_DISCONNECT,
                 NRF_GPIO_PIN_NOPULL,
                 NRF_GPIO_PIN_H0S1,       // Require High Drive low level
                 NRF_GPIO_PIN_NOSENSE);

RE: GPIO PIN issue

gdutk001 — Tue, 23 Oct 2018 19:27:47 GMT

Im not trying to read the value on the pin, i'm trying to drive the pin high and measure it using an oscilloscope. Are you saying that NRF->P0->OUT = 0xFFFFFFFF will not drive the pins high? I am using NRF->P0->OUT = 0xFFFFFFFF to try and drive all the pins high and see if i can measure a difference on the pins on the development board however that is not working. is this not what NRF->P0->OUT is meant for? my guess is that im somehow not initializing the pins on the port correctly however i havent been able to verify that.

RE: GPIO PIN issue

hmolesworth — Tue, 23 Oct 2018 16:41:35 GMT

Unlike many simpler 8-bit devices most (all) ARM cores implement the io pin with separate out and in registers; reading the OUT register returns the last value written to the OUT register, not the value currently on the io pin. To read the pin, instead use the IN register. To further illustrate, look at the definition of nrf_gpio_pin_toggle() function.

You can do a quick check by replacing "&=" with "=" and "|=" with "=" in your example, although of course you are driving all 32 pins on P0.