Bootloader with FDS

RE: Bootloader with FDS

bjorn-spockeli — Wed, 05 Apr 2017 10:27:52 GMT

Yes, I forgot that the register must be cleared to prevent the device from staying in the bootloader when it should jump to the application. I added have fixed this in the snippet above.

RE: Bootloader with FDS

dblasco — Wed, 05 Apr 2017 10:24:14 GMT

I think I forgot to clear first the register. I added sd_power_gpregret_clr and now it does work. Thank you!

RE: Bootloader with FDS

dblasco — Wed, 05 Apr 2017 10:16:42 GMT

Thank you Bjørn, that worked. I didn't know it was so simple! However, when I upload the new application firmware through DFU, the device does not start the application automatically (I have to turn off and on the device). I suppose this is because the register still has the 0xB1 value, so I tried adding sd_power_gpregret_set(0,0x00); in bootloader, but it has no effect. Is there any explanation for this?

Thank you

RE: Bootloader with FDS

bjorn-spockeli — Wed, 05 Apr 2017 07:57:18 GMT

Hi dblasco,

if you want to enter bootloader mode from the application then you only have to write to one of the nRF52s GPREGRET registers(general purpose registers that are retained through a Soft Reset) and then check this register once you enter the bootloader on startup.

Thus, you only need to call the following snippet in your application when you want to enter bootloader mode.

err_code = sd_power_gpregret_set(0,0xB1);       
APP_ERROR_CHECK(err_code);       

sd_nvic_SystemReset();

In the bootloader you will have to modify the nrf_dfu_enter_check() in nrf_dfu.c to the following

__WEAK bool nrf_dfu_enter_check(void)
{    
     if(NRF_POWER->GPREGRET == 0xB1)
     {
           //Reset GPREGRET register so bootloader mode is not triggered when the device resets.
           NRF_POWER->GPREGRET = 0x00;       
           return true;   
     }       

     if (s_dfu_settings.enter_buttonless_dfu == 1)   
     {       
        s_dfu_settings.enter_buttonless_dfu = 0;       
        (void)nrf_dfu_settings_write(NULL);       
        return true;     
     }     
     return false;
}

Best regards

Bjørn