Bootloader shutdown after DFU instead of resetting

[ibrahim123]

Hi ,

I am using the secure bootloader example (SDK 15) as a template for my DFU solution. 

I am experiencing issue with the update process as the device shuts down after the update instead of reset. 

I tried to debug and saw that it reach the function bootloader_reset and run the NVIC_SystemReset function however it then shutdown. 

I am using a LDO for the voltage regulation in the circuit and initially i thought that it is related however i am using an app on the board that uses the same function to reset in order to go to the bootloader and that works fine. 

 

I verified it with the example in the SDK  without changes as well as my modified version. 

Please assist as i dont have any solid lead here.

 thanks in advance, 

Ibrahim

[Susheel Nuguru]

I tried to debug and saw that it reach the function bootloader_reset and run the NVIC_SystemReset function however it then shutdown. 

 There is no shutdown feature in nRF chips, the closest is the System OFF mode and calling NVIC_system reset should not make it go into that mode. Are you sure that this behavior happens due to the call NVIC_SystemReset? I highly doubt it.

[danny habot]

Hi Aryan, 

We Are using LDO to regulate the system voltage which might be the cause for this.

It has an enable pin that is set to a logic "1" and my guess is that during the reset it falls and the system shutdown. 

The reason it is weird for us is that we use the same function on the application and it does a reset correctly. 

Does the NVIC_SystemReset change all the pins to logic "0"? if so why is it different from the way it works on the application side and can we change it to avoid changing the pins?

[Susheel Nuguru]

danny habot said:

Does the NVIC_SystemReset change all the pins to logic "0"? if so why is it different from the way it works on the application side and can we change it to avoid changing the pins?

 Danny,

based on the below image you can see that the soft reset (NVIC_System reset) will reset the GPIO registers. So this should change all the logic to reset values before the configuration.

[danny habot]

OK, so it should be possible to move the chip to off mode and then wake it up to reset? 

Do you have an example how to do it?

[Susheel Nuguru]

we do not call it off mode, but it is system off mode and seems like this is what you need.

The system is made to go to deep sleep mode by calling either

NRF_POWER->SYSTEMOFF = 0x1; //when softdevice is not enabled  OR

sd_power_system_off(); //when softdevice is enabled.

a wakeup source needs to be configured before calling this and the wakeup will cause a system reset. This wakeup will not reset the GPIO registers so you will not see the pin status changing.

[ibrahim upright]

Hi Susheel,
We have got to work on this and we can see that in order to use NRF_POWER->SYSTEMOFF = 0x1 we need to define a source for wake up.
However from the thread (devzone.nordicsemi.com/.../nrf52832-system-off-with-wake-on-reset) we can use one of the following interrupt:
GPIO , LPCOMP, NFC however we need to have an internal trigger so we need an interrupt that we can control (like a timer for example).
Which interrupt can we use to trigger an immediate reset after the move to low power mode, as we need it to create a "reset" for the system that will retain the GPIO state?

Thanks A lot 

Ibrahim