Jumping to bootloader without DFU

RE: Jumping to bootloader without DFU

Vidar Berg — Tue, 14 Apr 2020 08:48:05 GMT

nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_DFU) calls NVIC_SystemReset() at the end of its shutdown procedure.

[quote userid="72280" url="~/f/nordic-q-a/60133/jumping-to-bootloader-without-dfu/244351"]Why do I see different behavior if I set GPREGRET and don't set it before calling[/quote]

It should be cleared before you call NVIC_SystemReset()/nrf_pwr_mgmt_shutdown() if you don't want the bootloader to enter DFU mode.

    /* Clear POWER->GPREGRET0 */
    err_code = sd_power_gpregret_clr(0, 0xffffffff);
    VERIFY_SUCCESS(err_code);

RE: Jumping to bootloader without DFU

CodeLoader — Tue, 14 Apr 2020 08:28:22 GMT

Why do I see different behavior if I set GPREGRET and don't set it before calling

nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_DFU)?

With NVIC_SystemReset() it seems to enter the bootloader

RE: Jumping to bootloader without DFU

Vidar Berg — Tue, 14 Apr 2020 07:36:55 GMT

Hello,

The bootloader will always run before the application after reset, so it is sufficient to just call NVIC_SystemReset() without setting the retention register first. The bootloader will only enter DFU mode if one of the "DFU_ENTER_METHOD" checks return true.