DK52 external programming

[Gueston]

Hi,

I need to power my external board while debugging with the DK52. Therefore I don't use the VDD connection from the DK52, I only connect the external VDD to SH_VTG.

I use Pin19, as follows:

P19                         External Board
3 (SH_VTG)          <->     VDD
4 (SH_SDWIO)        <->     SDWIO
5 (SH_SWCLK)        <->     SWCLK
6 (SH_SWO)          <->     SWO
7 (SH_RESET)        <->     RESET
8 (SH_GND_DETECT)   <->     GND

GND PIN of DK52     <->     GND

Is this correct? Because I connected it like this, and it worked. I can program, debug etc. But I also destroyed my DK52 with this, because while I was working later I forgot to connect the supply GND of my external board to the DK52 and suddenly the DK52 was not working anymore. How can it be destroyed like this?

So to be sure, is this the right way to connect it?

[Gueston]

Hi, any updates on this?

[Marjeris Romero]

Hi,

Sorry for the late reply. The voltage on the external board must match that of the development kit (DK). You write that you don't use the VDD connection from the DK52, so it's not given that VDD on the nRF52DK match your external VDD and most likely therefore you are seing problems.

BR,

Marjeris

[Gueston]

Yes, I don't use the VDD from DK52. The voltage of the external board is 2.5V, so lower then the DK52. Is it possible to supply the DK52 from the external board by not switching the DK52 on, and still make use of the USB for debug purposes?

[Marjeris Romero]

Is there a reason why you are not supplying you external board from the nRF52DK? The voltage supported by the external debugging/programming is 3.0V.

[Gueston]

The reason is that this external board is supplied with 7.4V and has an LDO which supplies 2.5V for the nRF chip. Only reason for connecting the 7.4V is because I can debug the whole board in this way, if I supply it with the nRF52DK then only parts of the circuit work.