Bootloader takes to long to go to the application

[Matze]

Hello,

I'm using the nRF51422 with a dfu dual bank bootloader with SDK 11. I can programm the uController with the Softdevice and the bootloader and afterwards load successfully load the application over dfu on the device. After the package ist transported the uController startes the application as planed. But when I send my device into sleep mode and wake it up it starts in the bootloader and wait für 2 minutes bevor it starts the application.

Is there a way to let it go direktly to the application?

[Vidar Berg]

Hello,

The bootloader will by default enter DFU mode on boot if one of the following conditions are met (times out from DFU mode after 2 minutes):

1. if NRF_POWER->GPREGRET == BOOTLOADER_DFU_START. 

2. BOOTLOADER_BUTTON is pulled low on startup

Are you using a custom board, or are you testing on a development kit. In case you are using a custom board, is BOOTLOADER_BUTTON enabled and do you have it connected to a button that is active low? 

[Matze]

thanks that was helpfull. I found my mistake: I am useing an custom board and the Pin 20 was already taken so the programm thought the button was pressed.

I want to let the application set a flag which tells the bootloader that there is an update avalible. I want to use the one of the 8 bits form NRF_POWER->GPREGRET but I don't know which of them I could use without distubing dfu_dual_bank_ble_s130_pca10028.

I didn't find a list of usage of the bits. Can you tell me one?

[Vidar Berg]

Glad you found the problem. We already use GPREGRET to signal the bootloader to enter DFU mode, see "adding DFU service support to an application". Is this what you want to do? 

Bootloader will by default enter DFU mode if GPREGRET is set to 0xB1 (BOOTLOADER_DFU_START).