Can I use the NRF52 DK JTAG port to program my own custom built device? And does it happen automatically when I upload code to the DK through Segger?

[RyanA]

Hello,

I have tested and verified the code for my application on the NRF52 DK, but now I need to program my own custom device using the nRF52832 chip. I saw there was a JTAG port for Serial wire debugging on the DK and so I was wondering if I can use that to program my custom device when I upload code to the DK from Segger.

Thanks for any help.

[jkyle]

Yes you can, just make sure the external device is powered first. You can connect the Debug out port (P19 on the DK) to your custom board with a ribbon cable if you included a similar 10 pin header in your design. You can also connect the boards using P20 on the DK as described in this answer (note that the diagram in the answer given by Remi is powering the board from the DK so no external power is needed). If the DK detects an external voltage is connected it will automatically program the external board instead of the chip on the DK.

[RyanA]

Are you referring to Vref when you say power? Does the JTAG port do this automatically or would I need to conect it to a 3.3 V pin on the board? Also once connected, can I upload code to it through Segger embedded studio as I would regularly for the DK?

[jkyle]

Your custom device needs to have power supplied to it in some way. This can be a battery, external power supply, or Vdd and GND from the DK board.

The VTG and GND Detect pins on the dev kit sense the voltage level on the target board, so they should be connected to VDD and GND on your custom device. The SWD IO and SWD CLK also should be connected to the corresponding pins on your device. You can do this either with P20 on the DK or using P19 (schematic below)

Once everything is connected you should be able to upload code as you normally would with SES. If everything is connected correctly your custom device will be programmed instead of the chip on the dev kit.

[RyanA]

Thanks, I am getting the picture now but I am still confused on these GND and VCC pins. So I need to bus the VCC and GND pins on my device not only to the Debug out connector but also to the boards actual 3.3V out pin and GND pin?

[jkyle]

Yes, the debug out connector will not supply power to your custom board. You will need to power it from another source, which can be the VDD and GND pins of the dev kit.