sd_app_evt_wait only waits until central is connected

[angelcruiz]

Hello,

I'm trying to put a BLENano board to slepp every loop iteration. These are te steps:

1. setup:

   sd_power_mode_set(NRF_POWER_MODE_LOWPWR);
   NRF_POWER->TASKS_LOWPWR = 0; NRF_POWER->DCDCEN = 0x00000000;

2: loop:

   [...]

   sd_app_evt_wait();

   BLECentral central = ble.central(); 

   // if a central is connected to peripheral:
   if (central) {        

        sd_app_evt_wait();

       // while the central is still connected to peripheral:
       while (central.connected()) {
              sd_app_evt_wait()
              [...]
    }

   [...]

The first time sd_app_evt_wait is called, it waits until a central is connected. But then, the execution enters the inner loop and sd_app_evt_wait returns instantly.

I've read things about pending events or interrupts, bu I've not managed to get to work. I've also tried calling sd_nvic_EnableIRQ(SWI2_IRQn); with a proper empty SWI2_IRQHandler, but then sd_app_evt_wait never returns and no central can connect to the device.

Please, ¿is there something with the library I have to setup in order for this to work?

Thanks!

[John]

Are you shure sd_app_evt_wait is returning instantly, or just very quickly? Once you are in a connection, the host will be sending you connection events to drive the communications. Those will arrive at some interval usually in the milli-second or 10's of milli-second range. Those are probably waking you up and you just need to go back to sleep if there is nothing to do.

[angelcruiz]

That's what I first thought, but when I disconnect the central (I've tried two, desktop dongle and mobile), the sleep/awake still happens. I'm writing to serial before and after the sd_app_evt_wait to debug it, but it doesn't affect anything as the first call to sd_app_evt_wait does wait indeed.

[John]

Well, that's a bummer and there goes the easy answer. From what you are describing the next best guess is that there is a interrupt that isn't being properly cleared preventing you from going to sleep. I think there are some good posts on the board about debugging those.

[angelcruiz]

I've narrowed it a little bit. sd_nvic_GetPendingIRQ tells there's a pending CAN1 SCE Interrupt. May I just clear it or is it worth knowing why is there?

[John]

You've pretty much gone beyond my knowledge as I've done most of my work using Nordic as a Peripheral device and not a central. That said, if my Googling is any good, that CAN1 SCE maps to IRQ number 22 which is SWI2 on the nRF. SWI2 is used by the soft device for protocol and SoC events. My guess is that the stack wants you to do something to respond to an event which would clear the IRQ, you can try clearing it but I don't know what affect that may have on stack operation if any.