Secure Serial DFU, app with UART stuck at bootloader

RE: Secure Serial DFU, app with UART stuck at bootloader

PB — Tue, 25 Jul 2017 05:08:21 GMT

I'll experiment a little more and report it on github. Thank you for your help Bjørn

RE: Secure Serial DFU, app with UART stuck at bootloader

bjorn-spockeli — Mon, 24 Jul 2017 11:31:23 GMT

@pb: Yes, with the latest version of nrfutil v3.2.0 you should be able to set the baudrate as well as enabling/disabling HWFC. The chosen baudrate must of course match the one configured in the bootloader example. Could you report this as an issue in the nrfutil github repo(here is the link)?

RE: Secure Serial DFU, app with UART stuck at bootloader

PB — Mon, 24 Jul 2017 10:31:53 GMT

Also I've tried using the --baud-rate=115200 param of nrfutil but it didn't have an impact on the events I've described above.

RE: Secure Serial DFU, app with UART stuck at bootloader

PB — Mon, 24 Jul 2017 10:31:22 GMT

So as it turns out my problem had a different source than problems with BL or the APP. nrfutil uses a lower baud rate (19200, am I right?) for firmware transfer than my APP uses (115200). As a result, my OS (Linux) by default selected the last used baud rate, even if i specified otherwise when calling screen /dev/ttyACM0 115200 it still rolled back to one used by nrfutil.

So to clear this and have a repeatable working DFU i have to do the following steps:

perform DFU. App goes through BL and boots which I observe with LED states on DK
Run screen /dev/ttyACM0 115200 - doesn't work, both sending
Run screen /dev/ttyACM0 19200 - this throws out some trash into the terminal
Run screen /dev/ttyACM0 115200 - this now works

Very confusing. I haven't inspected nrfutil yet, but is it possible that there should be some flush after DFU?

RE: Secure Serial DFU, app with UART stuck at bootloader

bjorn-spockeli — Thu, 20 Jul 2017 13:29:14 GMT

@pb: Yes, the experimental_ble_app_buttonless_dfu exaple found in examples\ble_peripheral\experimental_ble_app_buttonless_dfu has a precompiled hex file in the hex folder.

RE: Secure Serial DFU, app with UART stuck at bootloader

PB — Thu, 20 Jul 2017 12:25:11 GMT

You are right. But I've tried smaller even lower values than 0x59000 which unfortunately doesn't change anything in terms of correct application boot.

Are there maybe any example sources of the applications bundled as .hex with the SDK, eg. from examples/dfu/ble_dfu_send_hex/test_images_update_*/ ? I really don't see what can be wrong here and having some source reference would definitely help narrowing down on possible cause.

RE: Secure Serial DFU, app with UART stuck at bootloader

bjorn-spockeli — Thu, 20 Jul 2017 11:46:49 GMT

The length of the application Flash section should be 0x59000 since the Secure Serial Bootloader starts at 0x78000.

RE: Secure Serial DFU, app with UART stuck at bootloader

PB — Wed, 19 Jul 2017 16:25:22 GMT

output from RTT is

:DEBUG:In nrf_bootloader_init
:DEBUG:In real nrf_dfu_init
:DEBUG:running nrf_dfu_settings_init
:DEBUG:Enter nrf_dfu_continue
:DEBUG:Valid App
:DEBUG:Enter nrf_dfu_app_is_valid
:DEBUG:Return true. App was valid
:DEBUG:Enter nrf_dfu_app_is_valid
:DEBUG:Return true. App was valid
:DEBUG:Jumping to: 0x0001f000
:DEBUG:Running nrf_bootloader_app_start with address: 0x0001f000
:DEBUG:Disabling interrupts
:DEBUG:Setting SD vector table base: 0x0001f000

RE: Secure Serial DFU, app with UART stuck at bootloader

PB — Wed, 19 Jul 2017 16:24:27 GMT

Had to split my response into parts

But the results are the same. The thing which I don't also understand is why the bootloader doen't go into the app even though it finds it valid. My apps .ld is FLASH (rx) : ORIGIN = 0x1f000, LENGTH = 0x61000- tried reducing it but no luck. I've also reduced my firmware to total minimum and it still doesn't start from BL:

int main(void)
{
    uint32_t err_code;
    bool     erase_bonds;
    err_code = app_timer_init();
    APP_ERROR_CHECK(err_code);
    log_init();
    buttons_leds_init(&erase_bonds);
    nrf_clock_lf_cfg_t clock_lf_cfg = NRF_CLOCK_LFCLKSRC;
    SOFTDEVICE_HANDLER_INIT(&clock_lf_cfg, NULL);
    NRF_LOG_INFO("Firmware: reset_to_dfu\r\n");
    for (;;)
    {
        power_manage();
    }
}

RE: Secure Serial DFU, app with UART stuck at bootloader

PB — Wed, 19 Jul 2017 16:22:27 GMT

I've tried a few things, for example the code below:

void handle_dfu_start()
{
    uint32_t err_code;
    app_uart_flush();
    app_uart_close();

    softdevice_handler_sd_disable();
    err_code = sd_softdevice_disable();
    APP_ERROR_CHECK(err_code);

    err_code = sd_power_gpregret_clr(0, 0xffffffff);
    APP_ERROR_CHECK(err_code);

    err_code = sd_power_gpregret_set(0, BOOTLOADER_DFU_START);
    APP_ERROR_CHECK(err_code);

    NVIC_SystemReset();

}

RE: Secure Serial DFU, app with UART stuck at bootloader

bjorn-spockeli — Tue, 18 Jul 2017 14:21:34 GMT

Could you post the code where you uninitializing the UART peripheral in the application before you jump to the bootloader? Also,is teh SoftDevice enabled when you call handle_dfu_start()?