How to enter DFU Mode

RE: How to enter DFU Mode

Christopher — Wed, 11 May 2016 17:08:22 GMT

Both approaches are possible. Depending on the BLE connection parameters, the timeout can be several seconds. I always prefer to correctly close a BLE connection.

RE: How to enter DFU Mode

John — Wed, 11 May 2016 16:56:17 GMT

Not sure I agree with that. It makes sense if you are doing the "soft reset" where you enter the bootloader by jumping into the bootloaders entry point instead of doing a chip reset. However, if you are doing a chip reset the stack is going to be coming up from scratch and any connection you had will be taken down by a connection supervisor timeout. Just seems like additional complexity if you are doing a chip reset.

RE: How to enter DFU Mode

Christopher — Wed, 11 May 2016 16:23:21 GMT

Before resting to the bootloader mode, you should prepare the reset. Calling directly the NVIC_SystemReset(); method is not a good option IMO:

void reset_prepare(void) {
  uint32_t err_code;

  // Change a LED state

  // Disconnect from BLE peer if connected
  // If not connect, stop advertising if enabled

  err_code = ble_conn_params_stop();
  APP_ERROR_CHECK(err_code);
}

// Disable the SoftDevice and restart properly in bootloader mode
void bootloader_start() {
  // A "simple" reset is not enough, the SD and IRQs must be disabled first
  ble_dfu_evt_t evt;
  memset(&evt, 0, sizeof(evt));
  evt.ble_dfu_evt_type = BLE_DFU_START;
  dfu_app_on_dfu_evt(&m_dfus, &evt);
}

In my case, I generate a ble_dfu_evt_t event to restart properly in bootloader mode. I also use the reset_prepare function to close a BLE connection or stop advertising before entering in bootloader mode.

RE: How to enter DFU Mode

John — Wed, 11 May 2016 13:07:54 GMT

My post above was discussing changes needed in the device FW. It shouldn't impact the python script I don't think.

RE: How to enter DFU Mode

John — Wed, 11 May 2016 13:07:03 GMT

This is pretty close to what I am doing as well.

RE: How to enter DFU Mode

Sven — Wed, 11 May 2016 12:55:59 GMT

Hi!

I am using SDK10 nRF51 and dual boot S310 version of the DFU.

Also i do not intend to share information and I do not have BLE stack set up in my app (using ANT)

Two steps:

In my app call the following:

NRF_POWER->GPREGRET = 0xB1; NVIC_SystemReset();
(You can disable the option at all or do something else)

in /examples/dfu/bootloader/main.c

I simply disabled the check inside ble_stack_init() by removing the if (init_softdevice). I need to always startup the SD since I do not have it enabled in my app and I am doing complete reset in step 1.

Also I disabled anything that is connected to GPIO since on my custom board I do not have buttons etc...

So at the end of the day bootloader(DFU) always starts first, checks the GPREGRET register. If it matches the magic value, voilaa.

RE: How to enter DFU Mode

Siva Subrahmanyam — Wed, 11 May 2016 12:47:55 GMT

So from nrfutil python script i should set GPREGRET register. i am using example/dfu/bootloader souce code on PCA10001 evaluation kit with s120 softdevice. What are the changes needed.

RE: How to enter DFU Mode

John — Wed, 11 May 2016 12:31:13 GMT

The short answer is yes. The newer SDKs provide some very nice features for entering the bootloader without a button or even a reset. Which allows sharing of bonding information, or avoiding bonding being an issue for the bootloader. That said, you don't have to use all of that. In our case we didn't need the functionality and in fact it was causing some problems due to the fact that there wasn't a system reset to stop other portions of our system. So, I simplified bootload entry to just setting the GPREGRET register and doing a system reset. It required changes in the bootloader, but you have the source code so you can modify it to your needs.