DFU on one button device

[Moritz]

Hi there,

I'm trying to get a one button nrf52832 device to behave like the following:

1. Button press short: RESET or WAKE (depending on POWER state)

2. Button press long: POWEROFF

3. Button pressed while being connected to power source: DFU

Features 2 and 3 work fine, but every time I wake the device with a button press it goes to DFU instead of running the app.

I played around with GPREGRET a bit, but it seems those registers get overwritten by the bootloader. 

This post (https://devzone.nordicsemi.com/f/nordic-q-a/33507/bootloader-deep-sleep/128954#128954) talks very briefly about "disabling the BOOTLOADER_BUTTON", but it's unclear to me how to do that, and still retain the wake functionality. 

So if somebody could shed some light on wether it's possible to get features 1-3 implemented and if yes, I'd be very thankful.

Best

[Vidar Berg]

Hi,

This post (https://devzone.nordicsemi.com/f/nordic-q-a/33507/bootloader-deep-sleep/128954#128954) talks very briefly about "disabling the BOOTLOADER_BUTTON", but it's unclear to me how to do that, and still retain the wake functionality. 

Do you enter system OFF from the bootloader code? The BOOTLOADER_BUTTON is not directly tied to the wake-up functionality, but it will initialize the pin to input with sense enabled, see nrf_bootloader::dfu_enter_button_init().

sdk_config.h settings if you use SDK 15.3.0:

// </h> 
//==========================================================

// <h> DFU mode enter method 

//==========================================================
// <e> NRF_BL_DFU_ENTER_METHOD_BUTTON - Enter DFU mode on button press.
//==========================================================
#ifndef NRF_BL_DFU_ENTER_METHOD_BUTTON
#define NRF_BL_DFU_ENTER_METHOD_BUTTON 1
#endif
// <o> NRF_BL_DFU_ENTER_METHOD_BUTTON_PIN  - Button for entering DFU mode.
 
// <0=> 0 (P0.0) 
// <1=> 1 (P0.1) 
// <2=> 2 (P0.2) 
// <3=> 3 (P0.3) 
// <4=> 4 (P0.4) 
// <5=> 5 (P0.5) 
// <6=> 6 (P0.6) 
// <7=> 7 (P0.7) 
// <8=> 8 (P0.8) 
// <9=> 9 (P0.9) 
// <10=> 10 (P0.10) 
// <11=> 11 (P0.11) 
// <12=> 12 (P0.12) 
// <13=> 13 (P0.13) 
// <14=> 14 (P0.14) 
// <15=> 15 (P0.15) 
// <16=> 16 (P0.16) 
// <17=> 17 (P0.17) 
// <18=> 18 (P0.18) 
// <19=> 19 (P0.19) 
// <20=> 20 (P0.20) 
// <21=> 21 (P0.21) 
// <22=> 22 (P0.22) 
// <23=> 23 (P0.23) 
// <24=> 24 (P0.24) 
// <25=> 25 (P0.25) 
// <26=> 26 (P0.26) 
// <27=> 27 (P0.27) 
// <28=> 28 (P0.28) 
// <29=> 29 (P0.29) 
// <30=> 30 (P0.30) 
// <31=> 31 (P0.31) 

#ifndef NRF_BL_DFU_ENTER_METHOD_BUTTON_PIN
#define NRF_BL_DFU_ENTER_METHOD_BUTTON_PIN 16
#endif

// </e>

// <q> NRF_BL_DFU_ENTER_METHOD_PINRESET  - Enter DFU mode on pin reset.
 

#ifndef NRF_BL_DFU_ENTER_METHOD_PINRESET
#define NRF_BL_DFU_ENTER_METHOD_PINRESET 0
#endif

// <q> NRF_BL_DFU_ENTER_METHOD_GPREGRET  - Enter DFU mode when bit 1 (0-indexed) is set in the NRF_POWER_GPREGRET register.
 

#ifndef NRF_BL_DFU_ENTER_METHOD_GPREGRET
#define NRF_BL_DFU_ENTER_METHOD_GPREGRET 1
#endif

// <q> NRF_BL_DFU_ENTER_METHOD_BUTTONLESS  - Enter DFU mode when the Boolean enter_buttonless_dfu in DFU settings is true.
 

#ifndef NRF_BL_DFU_ENTER_METHOD_BUTTONLESS
#define NRF_BL_DFU_ENTER_METHOD_BUTTONLESS 0
#endif

[Moritz]

No. I power down from the app. I managed to get something working by reading RESETREAS like this:

uint32_t reset_reason;
reset_reason = NRF_POWER->RESETREAS;
NRF_POWER->RESETREAS = 0x00000000;

// if not power cycle
if (reset_reason > 0) {
    nrf_bootloader_app_start();
} else {
    err_code = nrf_bootloader_init(dfu_observer);
    APP_ERROR_CHECK(err_code);
}

[Vidar Berg]

Hi,

Not sure I understand why it helps to check the RESTETREAS register helps. Do you have PINRESET enabled on this pin? 

[Moritz]

Well, I use the same button for entering the DFU and for waking up the device. The device should only go into DFU mode if the restart was caused by a power cycle. In order to distinguish the restart after deep sleep from a power cycle I check RESETREAS in the bootloader. 

[Vidar Berg]

I see, thanks. I suggest that you step through the dfu_enter_check() function to see where 'true' is being returned if you want to debug this further. Maybe the gpregret flag wasn't cleared?