Buttonless Secure DFU with WDT needs DFU twice

RE: Buttonless Secure DFU with WDT needs DFU twice

Guillaume LS — Tue, 14 Nov 2017 08:34:08 GMT

You will face the same watchdog issue if you try to update the SoftDevice. I think the same fix has to be applied also in the nrf_dfu_sd_continue_impl() function.

RE: Buttonless Secure DFU with WDT needs DFU twice

Hung Bui — Tue, 11 Apr 2017 10:42:40 GMT

Good to know it worked. Thanks for the tip, I will update my blog.

RE: Buttonless Secure DFU with WDT needs DFU twice

kamisen — Tue, 11 Apr 2017 07:43:15 GMT

Thanks a lot. I think you can update your Secure DFU blog with the WTD handle. ;-)

RE: Buttonless Secure DFU with WDT needs DFU twice

kamisen — Mon, 10 Apr 2017 13:43:59 GMT

Thanks @Hung Bui. I'll try your suggestion. And in the same question link @etienne said he solved the issue "by checking and fixing the compiler optimisation flag for the nano_ecc library". You can see it.

RE: Buttonless Secure DFU with WDT needs DFU twice

Hung Bui — Mon, 10 Apr 2017 10:25:06 GMT

Hi Kamisen,

I'm sorry indeed for late response. I was occupied by something else and forgot to get back to the case.

I checked again, it seems that if we only put the NRF_WDT->RR[0] = WDT_RR_RR_Reload; inside wait_for_event() it's not enough as after we receive the image and then do swapping it may last longer than 2 seconds ( i tried 10seconds and it worked) and cause a WDT reset. What you can do is to put the NRF_WDT->RR[0] = WDT_RR_RR_Reload; also inside the while loop in nrf_dfu_app_continue() in nrf_dfu_utils.c like this:

NRF_LOG_INFO("Enter nrf_dfu_app_continue\r\n");

    // Copy the application down safely
    do
    {   NRF_WDT->RR[0] = WDT_RR_RR_Reload;

        cur_len = (length_left > split_size) ? split_size : length_left;

Please try and let me know if it fix the issue for you.

RE: Buttonless Secure DFU with WDT needs DFU twice

kamisen — Fri, 07 Apr 2017 14:22:10 GMT

@Hung Bui , any progress? Thanks.

RE: Buttonless Secure DFU with WDT needs DFU twice

Hung Bui — Wed, 29 Mar 2017 15:35:01 GMT

Thanks, it seems that on the first DFU we receives the application, and replaced the old application but haven't finish the process properly and got a WDT reset. I will try to reproduce the issue on the SDK v12 and get back to you tomorrow if we manage to make an example.

RE: Buttonless Secure DFU with WDT needs DFU twice

kamisen — Wed, 29 Mar 2017 15:31:28 GMT

The 51822 chip is running into application(WDT runs too)
Use iOS nRF toolbox to do DFU with the relating secure Zip file that have application but no bootloader or softdevice in it.(The first time DFU)
The DFU finish in App but the 51822 chip is still adverting as DfuTarg and run in bootloader proram not in application.
Use iOS nRF toolbox to do DFU with the same secure Zip file again.(The second time DFU)
The DFU finish in App and the 51822 chip runs into application.

RE: Buttonless Secure DFU with WDT needs DFU twice

Hung Bui — Wed, 29 Mar 2017 14:33:28 GMT

Sorry I was testing on SDK v13.

I still don't understand what you mean by "DFU still need to do twice" or "twice means that only entering bootloader twice by LED indicating. " Could you describe what exactly you see ? until which stage the first DFU process get to before it reset ?

RE: Buttonless Secure DFU with WDT needs DFU twice

kamisen — Wed, 29 Mar 2017 13:47:08 GMT

Sadly it is still not work for me. After adding the __WFI(); the DFU still needs to do twice. And the first time DFU's transmit speed is much slower. And I found my nrf_dfu.c doesn't have sd_app_evt_wait(); in wait_for_event(). My sdk is 12.2. I knew it can use timer to feed the dog in bootloader but when I added it, the storage is over the limit.

RE: Buttonless Secure DFU with WDT needs DFU twice

Hung Bui — Wed, 29 Mar 2017 13:09:04 GMT

Hi Kamisen,

Seems that I found the problem, it was with wait_for_event(). Inside that function we call sd_app_evt_wait(); This call won't return if you don't have any application event or receive Softdevice event. If you replace that function with simply __WFI(), then we can be sure the CPU wake up and do WDT feeding every time we have a BLE activity. This worked for me :

static void wait_for_event()
{
    // Transport is waiting for event?
    while(true)
    {
	     NRF_WDT->RR[0] = WDT_RR_RR_Reload;
        // Can't be emptied like this because of lack of static variables
        __WFI();

        app_sched_execute();
    }
}

A better way of doing this is to setup a timer with a timeout smaller than 2 seconds to feed the dog.

RE: Buttonless Secure DFU with WDT needs DFU twice

kamisen — Wed, 29 Mar 2017 02:43:02 GMT

When I debug the bootloader, I found the wait_for_event() can be entered again and agian. So the NRF_WDT->RR[0] = WDT_RR_RR_Reload will be called frequently. Here is the code:

static void wait_for_event()
{
    // Transport is waiting for event?
    while(true)
    {
        NRF_WDT->RR[0] = WDT_RR_RR_Reload;
        // Can't be emptied like this because of lack of static variables
        app_sched_execute();
    }
}


void nrf_dfu_wait()
{
    NRF_WDT->RR[0] = WDT_RR_RR_Reload;
    app_sched_execute();
}


uint32_t nrf_dfu_init()
{
    uint32_t ret_val = NRF_SUCCESS;
    uint32_t enter_bootloader_mode = 0;

    NRF_LOG_INFO("In real nrf_dfu_init\r\n");

    nrf_dfu_settings_init();

    // Continue ongoing DFU operations
    // Note that this part does not rely on SoftDevice interaction
    ret_val = nrf_dfu_continue(&enter_bootloader_mode);
    if(ret_val != NRF_SUCCESS)
    {
        NRF_LOG_INFO("Could not continue DFU operation: 0x%08x\r\n");
        enter_bootloader_mode = 1;
    }

    // Check if there is a reason to enter DFU mode
    // besides the effect of the continuation
    if (nrf_dfu_enter_check())
    {
        NRF_LOG_INFO("Application sent bootloader request\n");
        enter_bootloader_mode = 1;
    }

    if(enter_bootloader_mode != 0 || !nrf_dfu_app_is_valid())
    {
        timers_init();
        scheduler_init();

        // Initializing transports
        ret_val = nrf_dfu_transports_init();
        if (ret_val != NRF_SUCCESS)
        {
            NRF_LOG_INFO("Could not initalize DFU transport: 0x%08x\r\n");
            return ret_val;
        }

        (void)nrf_dfu_req_handler_init();

        // This function will never return
        NRF_LOG_INFO("Waiting for events\r\n");
        wait_for_event();
        NRF_LOG_INFO("After waiting for events\r\n");
    }

    if (nrf_dfu_app_is_valid())
    {
        NRF_LOG_INFO("Jumping to: 0x%08x\r\n", MAIN_APPLICATION_START_ADDR);
        nrf_bootloader_app_start(MAIN_APPLICATION_START_ADDR);
    }

    // Should not be reached!
    NRF_LOG_INFO("After real nrf_dfu_init\r\n");
    return NRF_SUCCESS;
}

RE: Buttonless Secure DFU with WDT needs DFU twice

Hung Bui — Tue, 28 Mar 2017 12:36:52 GMT

It's pretty clear that the WDT was not fed properly in the bootloader , causing a reset and it enter the DFU bootloader again, this time without WDT and it works. I don't know how would it enter DFU on the second reset instead of starting application. Should be pretty easy to figure out why, by debugging the bootloader.

The NRF_DRV_WDT_DEAFULT_CONFIG will set the WDT timeout to 2 seconds which should be long enough. My suggestion for testing is to modify DFU mode , that instead of starting advertising, you can put an infinite loop there and do only one task of feeding the dog. Just to check if it can run normally or a reset would occurs.

RE: Buttonless Secure DFU with WDT needs DFU twice

kamisen — Tue, 28 Mar 2017 02:45:24 GMT

I mean the default value is NRF_DRV_WDT_DEAFULT_CONFIG. DFU twice means that only entering bootloader twice by LED indicating. I think it must be related with WDT but don't know how to solve it.

RE: Buttonless Secure DFU with WDT needs DFU twice

Hung Bui — Mon, 27 Mar 2017 14:57:13 GMT

What do you mean by default value ? What exactly was the timeout ? When you say DFU twice, meaning it actually enter the application twice or only once and then enter DFU bootloader twice ? I suspect that on the reset after the first trial, it enter bootloader again and this time WDT doesn't run ?

RE: Buttonless Secure DFU with WDT needs DFU twice

kamisen — Mon, 27 Mar 2017 13:04:02 GMT

The WDT timeout is default value. I can be ture of feeding dog by a led showing in bootloader or in application. Even feeding not frequently enough, it can not explain the situation that needs DFU twice every time.

RE: Buttonless Secure DFU with WDT needs DFU twice

Hung Bui — Mon, 27 Mar 2017 11:00:04 GMT

What was your WDT timeout ? Can you be sure you will feed the dog frequently enough to avoid WDT timeout ? When you enter wait_for_event() then get to CPU sleep mode, it will only wake up and feed the dog when there is BLE event.