nrf52811 dfu issue

[nebojsar]

Hi, I'm a novice in embedded systems. I have board based on nrf52811 and firmware written for my device but when I received my board from production I could not load firmware because there is no DFU on board.  I see device as AT 52811 and I can connect but no option to load firmware. 

I understand that I will probably need to make DFU bootloader using nrf util but I am not sure that I will be able to load the current firmware with the DFU bootloader that I made. Also board is very small with just a couple of sensors and it was intended to be updated over Bluetooth. Is it possible to load DFU bootloader over BT or device must be connected to the PC to do so?

[snoopy20]

There are three parts to an OTA system; DFU, SoftDevice (aka BLE) and App.

Softdevice and App don't know anything about DFU. The DFU and (usually) App use Softdevice for BLE.

So as a minimum you need DFU and SoftDevice installed by PC connection. Later the DFU can update all three parts of the system.

[nebojsar]

I thought I would need some sort of PC connection. On the board itself, I have a header for PC connection with SWDIO/SWDCLK pins.  Any suggestion on how to connect the board to the PC (USB or via some other controller) I assume I will need to make connection cable?

[snoopy20]

You can use pins on NRF52DK. There's also Segger J-LINK Edu and various models they do. As Nordic licensing comes with NRF52 it makes sense to stay in the ecosystem (and Segger is absolutely superb after all).

[nebojsar]

Ok, I will try to source one NRF52DK. Will NRF52840 development kit work as well (easier to source for me)?

[snoopy20]

Yeah, they all have Segger Jlink onboard. It is the cheapest way to do it as Segger JLink's by themselves can be expensive.