Strange behavior Button 2 and Button 3 on nRF51 DK

[Hieu]

Updates are moved to the end of the question

I created a modified version of pca10028.h and boards.h and have preprocessors changed so that the following new config is loaded:

// Custom LEDs definitions for PCA10028
#define LEDS_NUMBER    1

//#define LED_START      21
#define LED_1          21
#define LED_2          22
#define LED_3          23
#define LED_4          24
#define LED_5          25

#define LED_START      24
#define LED_STOP       25

//#define LEDS_LIST { LED_1, LED_2, LED_3, LED_4 }
#define LEDS_LIST { LED_4 }

//#define BSP_LED_0      LED_1
//#define BSP_LED_1      LED_2
//#define BSP_LED_2      LED_3
//#define BSP_LED_3      LED_4
#define BSP_LED_0      LED_4
#define BSP_LED_1      LED_5

#define BSP_LED_0_MASK (1<<BSP_LED_0)
#define BSP_LED_1_MASK (1<<BSP_LED_1)
//#define BSP_LED_2_MASK (1<<BSP_LED_2)
//#define BSP_LED_3_MASK (1<<BSP_LED_3)

//#define LEDS_MASK      (BSP_LED_0_MASK | BSP_LED_1_MASK | BSP_LED_2_MASK | BSP_LED_3_MASK)
#define LEDS_MASK      (BSP_LED_0_MASK | BSP_LED_1_MASK)
/* all LEDs are lit when GPIO is low */
#define LEDS_INV_MASK  LEDS_MASK

#define BUTTONS_NUMBER 0

#define BUTTON_1       17
#define BUTTON_2       18
#define BUTTON_3       19
#define BUTTON_4       20

I expected that this changed the BSP module to use pin 24 and 25 for LED display purpose.

Then in main.c I am setting some simple GPIO toggling behavior. Basically, at a button input interrupt event, the interrupt handler would set a flag, and in main()'s infinite loop, the according LED should be toggled. My code is basically exactly this

...

static bool m_input_it_flag = false;

...

/** @brief  Helper function to toggle output
  */
static void __forceinline toggle_output(void)
{
    nrf_gpio_pin_toggle(2);
    nrf_gpio_pin_toggle(LED_2);
}

/** @brief  Input pin interrupt handler
  */
void group1_input_it_handler(nrf_drv_gpiote_pin_t pin, nrf_gpiote_polarity_t action)
{
    m_input_it_flag = true;
//    toggle_output();
}

/** @brief  GPIO initialization
  */
void gpio_init(void)
{
    nrf_drv_gpiote_in_config_t  nrf_drv_gpiote_in_config;
    
    // Input ---------------------------------------------------------------------------------------
    // This could return either NRF_SUCCESS or NRF_ERROR_INVALID_STATE. However, NRF_ERROR_INVALID_STATE
    // simply means the GPIOTE module is already initialized, so that error could be ignored.
    nrf_drv_gpiote_init();
    
    memset(&nrf_drv_gpiote_in_config, 0, sizeof(nrf_drv_gpiote_in_config_t));
    nrf_drv_gpiote_in_config.sense = NRF_GPIOTE_POLARITY_TOGGLE;
    nrf_drv_gpiote_in_config.pull = NRF_GPIO_PIN_PULLUP;
    nrf_drv_gpiote_in_config.hi_accuracy = false;
    nrf_drv_gpiote_in_config.is_watcher = false;
    
    nrf_drv_gpiote_in_init(BUTTON_2, &nrf_drv_gpiote_in_config, group2_input_it_handler);
    nrf_drv_gpiote_in_event_enable(BUTTON_2, true);
    
    // Output --------------------------------------------------------------------------------------
    nrf_gpio_cfg_output(2);
    nrf_gpio_cfg_output(LED_2);
    
    nrf_gpio_pin_set(2);
    nrf_gpio_pin_clear(LED_2);
}

...

/**@brief Application main function.
 */
int main(void)
{
    ...
    gpio_init();
    ...
    
    for (;;)
    {
        ...
        if (m_input_it_flag)
        {
            toggle_output();
            m_input_it_flag = false;
        }
        ...
        
    }
}

I have trimmed the full code and change variable name not to make this post lengthy unnecessarily. However in the original code I have that above code for both Button 1, 2 and 3. They should toggle LED 1, 2 and 3, respectively.

Now come the fun part: For button 2 and 3, after I pressed them once, their output seem to adopt the behavior of LED 4 (blink while advertising), which is BSP LED 1. In particular, LED 2 and 3 starts to blink in sync with LED 4. Sometimes they blink with the same state. Sometime they blink with reversed state. The output just toggle in sync.

Button 1 does not cause this problem.

Also, if instead of setting flags and handle the job in main, I toggle the output right at the handler, then this problem does not happen.

I could post a video of this if requested, but that seems too much work right now.

Do anyone have any guesses on what is going on?

---

Edit 1: I am using nRF51 DK with SDK v10.0.0 and SoftDevice S110 v8.0.0.

---

Edit 2: After some discussion with Øyvind in the comment down below, I have found some further issue even when not using BSP.

main.c code: buggy_gpiote_in_flag_main.c

---

Edit 4: In Edit 2 and 3's attachment I forgot to remove some irrelevant includes and codes. Here is a better trimmed down main.c file buggy_gpiote_in_flag_main.c

I tested it and it should run and reproduce the issue simply by replacing main.c in SDK v10's ble_app_uart example.

At the beginning of the file are two macros DEV_CFG_USE_FLAG and DEV_CFG_USE_BSP. Setting them to 1 will change the code to use flag raising to run GPIO triggered code or to use BSP, respectively. Setting them to 0 will change the code to run event code directly in GPIO handler or to disable BSP.

Also here is the board support file that could be used with it to observe the weird behavior when used with BSP. It is basically the code I have in the post. pca10028_modded.h

---

[Øyvind Karlsen]

Hi,

I've also had trouble with unexpected behavior when running BSP and BLE simultaneously. What happens is that the function bsp_led_indication() in bsp.c will turn off all LEDs and then blink LED1.

LEDS_OFF(LEDS_MASK & ~BSP_LED_0_MASK & ~m_alert_mask);

// in advertising blink LED_0
if (LED_IS_ON(BSP_LED_0_MASK))
{
    LEDS_OFF(BSP_LED_0_MASK);
    next_delay = indicate == BSP_INDICATE_ADVERTISING ? ADVERTISING_LED_OFF_INTERVAL : ADVERTISING_SLOW_LED_OFF_INTERVAL;
}

You can comment out the line LEDS_OFF line. For me the BSP is too much of an abstraction and I prefer to implement buttons and LEDs myself to have full control over what is happening.

Best regards,

Øyvind

[Hieu]

Øyvind,

I tried a little more without BSP, and has observed that even without BSP, using nRF51 Button 2 and 3 along with flag raising still cause events to be tangled up with each other. Do you have any guess what is going on?

[Øyvind Karlsen]

Setting the LEDs in main might get tangled up in interrupts that occur at the same time. Since it works in the handler and not in main I guess this is what you are seeing.

If what you want to do is to toggle LEDs every time you press a button you can follow the BSP tutorial, as it implements this.

[Hieu]

Øyvind, I think my problem is a little different. What I am seeing is that after pressing button 2 or 3, pressing any button (1, 2 or 3) will cause button 2 or 3's flagged routine to run. For example, after pressing button 2, when I pressed button 1 I will see both LED 1 and 2 blink.

You could check that out with my attached main.c. It should work by just replacing it into an ble_app_uart example of SDK v10.

I would like to understand the root of this problem a little better for future use of GPIO interrupt and flags, since I foresee a need to run a heavy workload at an GPIO event.

[Øyvind Karlsen]

Hi,

Had to include some .h files and comment out ir_raw.h. When I compiled and ran it LED 1, 2 and 3 on the DK lit up, and these become unlit when I hold Button 1, 2 and 3 respectively. I am also able to connect to it using master control panel on a android device. None of the LEDs are blinking by themselves in either connected or advertising mode.