How to enter DFU mode with plain modules?

[dandyse]

My question is rather simple, yet I cannot seem to find any documents describing how to do this basic and first step of all:

I have bought plain MDBT42Q module and connected power. On my iPhone I have nRF Connect running that I want to use to install firmware.

But the devices don't have DFU mode activated. How do I force them to go into DFU mode? Please help!

[Einar Thorsrud]

Hi,

The nRF devices are shipped with an empty flash, and I assume that also applies to the MDBT42Q module when you get it from the module manufacturer. This means that it does not have any bootloader, and cannot enter DFU mode. Initial programming needs to be done via SWD, using a debugger or programer.

If you are new to nRF development I suggest you have a look at the nRF Connect SDK Fundamentals course.

[dandyse]

So after flashing and installing a bootloader ... I remember that in order to bring the buttonless device into DFU mode a specific pin had to be connected to power (or GND?) when powered on. I am unable to find that information, could you please advise?

[Einar Thorsrud]

This depends on which bootloader you have programmed and how you have configured it. Bootloaders are a bit complex, so if this is the very first thing you do then I would wait a bit and learn the basics of the nRF Connect SDK, for instance from the nRF Connect SDK Fundamentals that I already mentioned. After that, for bootloader specifics you can look at these samples as well as the documentation.