Switch to BLE DFU mode

[Automne]

Hello !

I have two devices with the same firmware, to switch in DFU mode I call this function :

void system_reset_to_dfu(void)
{
    NRF_POWER->GPREGRET = 0;
    NRF_POWER->GPREGRET = 0xB1;
    system_reset();
}

On the first device, I reset in BLE DFU mode.

On the others devices I reset in normal mode ... But I can read 0xB1 in NRF_POWER->GPREGRET register.

Do I need to allow BLE DFU mode somewhere ?

Any clues ?

Thanks Automn

[AndreasF]

Hi.

I think the issue is that you're not forcing memory write before you write to the same register twice.

Try this instead:

void system_reset_to_dfu(void)
{
    NRF_POWER->GPREGRET = 0;
    __DSB();
    NRF_POWER->GPREGRET = 0xB1;
    system_reset();
}

But why would you set it to 0 in the first place?

Best regards,

Andreas

[Automne]

Thanks for the quick answer,

I try with your code, I get set same result.

I also replace the code with nrf_function :

void system_reset_to_dfu(void)
{
    nrf_power_gpregret_set(0xB1);
    __DSB();
    system_reset();
}

It's the same, DFU work on my old device, but not on the new one.

At the restart I can read 0xB1 in the register :

log_info("NRF_POWER->GPREGRET = 0x%x", nrf_power_gpregret_get());

INFO - NONE - 0 - NRF_POWER->GPREGRET = 0xb1␊

Do I need to defined something in sdk_config.h ?

Best regards,

Automn

[AndreasF]

Hi again Automn.

Could you try to add a read event before system_reset(); ?

For example something like

(void)NRF_TIMER0->EVENTS_COMPARE[0];

Best regards,

Andreas

[Automne]

Hi again Andreas,

I added NRF_TIMER0->EVENTS_COMPARE[0]; before system_reset(), but it does not change anything.

Best regards,

Automn

[Automne]

Hi Andreas,

The DFU secure_bootloader was flash only on my olds devices but not on the new one. That's why I could not start in DFU mode.

I'm sorry for bother you for that kind of problems, thanks for your patience. 

Best regards,

Automn