Programming a nRF51822 in low voltage mode with the SWD interface of the nRF51 DK

[Christophe]

As explained by electronut in his Blog and Lijun here, it is possible to program an External nRF51822 board using the SWD interface of the nRF51-DK.

But what about a custom board using a nRF51822 in low voltage mode?

Are the four useful pins (SH_VTG, SH_SWDIO, SH_SWDCLK and SH_GND_DETECT) on a different voltage domain defined by voltage put on SH_VTG or are they using the same VIO than the all board?

If the SDW interface can be used to program a nRF51822 board in low voltage mode I guess it is important to make sure that the custom board is powered on before it is connected to the SWD interface as SH_VTG is low and SH_GND_DETECT is high by default.

Anyway I just don't want to ruin the custom board I will soon received by experimenting somethings like that!

So here is my question: Is it safe to use directly this SWD inteface to program a Custom board in low voltage mode or should I use a level translator between the nRF51-DK and my board? Any other suggestion allowing me to use my Development kit to program my board?

Thanks

[Nguyen Hoan Hoang]

You'll need a level translator or use same voltage as on the DK or use alternative debug jtag such as this one here or a full J-Link.

[Christophe]

Thank you for your answer.

I have a level translator board that might fit my design. I'll have a look at it and will try to use it. Anyway, if it doesn't work your IDAP-Link seems to be a very low-cost solution. I'll probably buy one in the near future.