How to put Application in Bootloader mode without using a Softreset?

[Roshan007007]

I am trying the ANT-OTA DFU Update using an ANT Stick and the nr51422 pca 10028 board.Using the OTA Tester (s210), I am currently doing an OTA Update with the s210 dual bank bootloader. But the application goes into bootloader mode using a NVIC soft reset .Is there another way to put the Application in Bootloader mode ,since my application goes to a power off and on mode frequently to save battery consumption. This would indicate that my application would go to Bootloader mode ,every time it wakes up from a sd_power_system_off. Any other method to put the application to bootloader mode, when it receives a specific ANT Payload? _

[AmbystomaLabs]

Two things: You say you have the device power on/off frequently to save power. You should really re-think this approach. The action of the processor booting, setting up software registers, initializing gpio, peripheral ports and communications stack, initializing clocks, etc., etc. uses gobs of power. I recently went through an exercise where I determined that the boot for a ble device was so traumatic that the lithium button cell voltage actually doesn't recover for several minutes. You should really boot once then go into power save and have user or application just wake up the processor out of power save.

On switching to boot loader without a system reset. You can do this. It is mentioned in one of the dfu tutorials (sorry can't remember where). Essentially, you just have your program do a graceful shutdown (save out registers, close flash) and switch the program counter to the start of bootloader code. The graceful shutdown part should get discussed on docs for brownout reset. Same idea anyway.

[AmbystomaLabs]

Well the term "bootloader" gets used a little loosely here. Technically the bootloader is the soft device which I assume you have even though you are using ANT instead of BLE. The processor always boots from 0x0 which is where the soft device starts (assuming one is loaded). Then the soft device looks to see if there is dfu code in its assigned space, if not then it goes straight to the application code. In the situation where there is SD and DFU code, the processor starts at 0x0 (ie, SD) then the code moves to the DFU code, the DFU code checks its local flag to see if it has installed valid application code, if there is valid application code then the program counter is moved to your app code and things run normally. In the event that there isn't valid app code the DFU code will sit in DFU mode waiting for OTA software. I hope this answers your question.