Bootloader doesn't load application on power-on

RE: Bootloader doesn't load application on power-on

dingari — Tue, 23 May 2017 13:51:06 GMT

Hi Hung Bui, I finally got around to debugging this. I posted an answer below.

RE: Bootloader doesn't load application on power-on

dingari — Tue, 23 May 2017 13:50:40 GMT

Well, I think I finally found the culprit.

I use hardware debouncing for the buttons on my board (couple of resistors and a capacitor). During initial power up of the board, the capacitor might not be fully charged by the time nrf_dfu_enter_check is called, leading the application to read a low level on the bootloader button pin, and thus staying in bootloader mode.

On my board a 100nF capacitor is initially charged through 200 kOhms, so a 20ms delay (100*10^(-9) * 200*10^3) at the top of main in my bootloader code is sufficient to make this problem go away.

RE: Bootloader doesn't load application on power-on

Hung Bui — Fri, 24 Mar 2017 11:39:03 GMT

You can also think of using logging debug, such as printing something out on UART/RTT

RE: Bootloader doesn't load application on power-on

dingari — Thu, 23 Mar 2017 18:36:52 GMT

I understand that it doesn't think my application is valid. But I'm failing to see why it then suddenly thinks it's valid after a reset through SWD.

The DFU procedure works as expected and the application starts normally after that. If I put the device in OFF mode, and wake it up, the bootloader loads the application. The only time where the bootloader doesn't load the application is if it loses power.

I'll see if I can re-produce this behaviour in with GDB (I'll need to catch the first power on).

RE: Bootloader doesn't load application on power-on

Hung Bui — Thu, 23 Mar 2017 17:05:55 GMT

If it advertise as DFUTarg and doesn't enter your application, meaning it thinks that the application is not valid. This could be due to CRC mismatch.

Do you do any flash operation in your application ?

Please step into bootloader code and check the return value of nrf_dfu_app_is_valid() inside nrf_dfu_init().

Could you test doing DFU with any of our example for example the ble_app_hrs .

RE: Bootloader doesn't load application on power-on

dingari — Thu, 23 Mar 2017 14:22:56 GMT

Hi, I said before that the bootloader starts advertising as DFUTARG.

I haven't had the chance to debug the bootloader yet.

RE: Bootloader doesn't load application on power-on

Hung Bui — Thu, 23 Mar 2017 14:18:53 GMT

Please give information on this:

When the bootloader didn't start application what did it do ?Would it advertise as DFUTarg ? Or it's simply bricked ?

Have you tried to debug the bootloader ?

RE: Bootloader doesn't load application on power-on

dingari — Thu, 23 Mar 2017 10:22:45 GMT

Hi, the device starts in the bootloader advertising as DFUTARG. There are two ways I can get it out of bootloader mode: Do a DFU update or issue a reset through SWD.

RE: Bootloader doesn't load application on power-on

Hung Bui — Thu, 23 Mar 2017 10:18:07 GMT

Hi,

How does the application start at the first place? I assume it only start on the first run if you do DFU update but not if you do a power rest after that ?

When the bootloader didn't start application what did it do ?Would it advertise as DFUTarg ? Or it's simply bricked ?

You may want to check what happened inside the bootloader, simply debug it, add a breakpoint in main and step the code (you may need to put optimization level to 0 )