nrf52 P19 external programming

[akshaey]

I really need your help regarding a problem. I developed my own pcb with nrf52 and verified it with your hw engineer. I just finished soldering and hooked it up with your Development kit via P19 to program it via Jtag. But when i flash any program in keil, it gets uploaded into the chip on DK and not on my pcb. I don't understand why this is happening? I have verified the GND and external VDD connections on P19 which are connected to the VDD and gnd of my pcb and my pcb is externally powered on 3.3V. So i don't get why the DK IS NOT programming my external chip. please help

thanks

[Sigurd]

Hi,

How have you connected P19 to your custom board? Note that the voltage supported by external debugging/programming is 3.0 V.

The target board must be self-powered by 3V (e.g. by coin.cell battery of 3V).

Then connect from header P19:

pin1 (EXT VTG) to target board VDD (3V).

pin2 (EXT_SWDIO) to target chip SWDIO.

pin3 and pin9 (GND and EXT_GND_DETECT) to target board GND.

pin4 (EXT_SWDCLK) to target chip SWDCLK.

---

Port P20 can also be used for external board programming. For P20 programming take a look at the figure here.

The voltage on your external board should match the voltage on the nRF5x-DK in order to successfully "switch" to an external target. Maybe the easiest way to do this is to power your target chip from one of the "VDD" pins available on the nRF5x-DK.

[akshaey]

hey thanks for your reply, its working with P20 correctly! but still its not working with p19 after connecting again i don't get it why..

[Sigurd]

Great that you got the P20 port to work. Regarding P19, maybe you have not connected the wires correctly, the schematic looks like this on the nRF52-DK:

But you can of course use P20 instead of P19 if you want.