Bootloader Deep Sleep

[Adriana]

Wich is the proper way to bring bootloader into deep sleep?

I'm using a modified version of the BLE Secure DFU Bootloader (SDK 14.1.0) for the nrf52810. I have added button support for trigger the sd_power_system_off function and the wakeup event. In this way I'm able to put the system in sleep mode. By pushing the button it starts advertising again and it is possible to establish connection, but not starting a DFU.

Can you give me some advice to fully understand how wakeup works and how to use it with bootloader?

Thank you

[Vidar Berg]

Hello,

A device will typically enter sleep from the main application (after advertisment timeout,etc.), and therefore not require any changes in the bootloader code, but you may need to disable the BOOTLOADER_BUTTON pin if you only have one button in your design, bootloader will enter DFU mode on startup if you use the same pin for wake-up. 

BOOTLOADER_BUTTON pin is not required if you implement support for buttonless dfu in your main app. 

 

[Adriana]

Hello,

I'm using buttonless dfu so I've disabled the BOOTLOADER_BUTTON pin. But actually I want to enter sleep from the bootloader when there is no main application.

I'm able to enter sleep from the inactivity timeout handler and also from the button handler, and after wakeup (from button) connect again to central device. But when I enter sleep from the button handler is not  possible to start a DFU process again. 

I'd like to understand how the wakeup works when there is only bootloader and no application

[Vidar Berg]

It shouldn't require any special considerations to implement deep sleep in the bootloader code. When you enter sleep from the button handler, does the system wake up and start advertising? 

[Adriana]

No, it remains in sleep mode. I've added button_app support for handling debouncing.

[Vidar Berg]

Is the problem that the chip doesn't wake up, or is it that it wakes up but doesn't start to advertise in DFU mode? Did you configure the wake-up pin from the button handler? Suggest to debug the bootloader and confirm that the wake up pin is configured correctly prior to entering system off. 

[Adriana]

The chip wakes up, and it starts advertising in DFU mode. I can even connect from central after wake up, but when I try to start a OTA DFU it fails.

System ON --> button event --> System OFF --> wake up from button --> System ON. Advertising --> Connect --> Start OTA DFU --> OTA Aborted

System ON. Advertising --> Connect --> Start OTA DFU --> OTA successfully completed

[Vidar Berg]

When the bootloader is in this state (DFU gets aborted), please try to kill the app on your phone, then try DFU again. This should ensure that the phone restarts DFU from scratch and re-sends to init packet instead of attempting continuation from a previous session, which may be the case if you entered system off during a transfer.