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Jlink alternative for 3.6v custom board

Jason

Hi, What's the best JLink alternative for a 3.6V custom board? I'm using NRF Connect SDK2.2.0 in VScode. The segger devices are expensive so I wondered if there's anything else.

My custom board has VCC, GND, SWDIO and SWDCLK pins for programming and debugging. 

I've been using an NRF52840-DK hooked up to my custom board via the SWD interface on P20. My current custom board is 2.8V, so this works fine.

I'm designing a new custom board which will have a 3.6v LDO, so the SWD interface will also be at 3.6V.

I believe that if I use an NRF52840DK that I can set VDD of the P20 debug interface up to 3.3v using UICR_REGOUT0_VOUT_3V3, but I cannot set it to 3.6v. Is this correct?

Can I use the nrf52840DK to program a 3.6v custom board?

I'd like to find something I can use as a debugger, and maybe a seperate device that can be used in the factory for programming the firmware. 

The Black Magic probe seems to support NRF52 (https://black-magic.org/getting-started.html) but with some caveats that I'm not certain about.

It doesn't look as straight-forward as a JLink. This devzone question suggests nrfjprog won't work for example. 

 RE: JTAG Programmer (under $100, not a DK) 

I'm not sure if there are other limitations that will make debugging difficult.

The NRF52840-DK and NRF52833-DK both seem like the best method at the moment except for the voltage concern.

Any help/advice is greatly appreciated

  • +1

    Hi,

    What's the best JLink alternative for a 3.6V custom board? I'm using NRF Connect SDK2.2.0 in VScode. The segger devices are expensive so I wondered if there's anything else.

    We always recommend SEGGER J-link.

    I believe that if I use an NRF52840DK that I can set VDD of the P20 debug interface up to 3.3v using UICR_REGOUT0_VOUT_3V3, but I cannot set it to 3.6v. Is this correct?

    Correct, by supplying the DK from the nRF_USB port and configuring the REG0.

    Can I use the nrf52840DK to program a 3.6v custom board?

    Unfortunately no, the maximum voltage of REG0 is 3V3, But you could use an external level shifter on the SWD lines between the DK and your custom board. 

    I'd like to find something I can use as a debugger, and maybe a seperate device that can be used in the factory for programming the firmware. 

    The Black Magic probe seems to support NRF52 (https://black-magic.org/getting-started.html) but with some caveats that I'm not certain about.

    It doesn't look as straight-forward as a JLink. This devzone question suggests nrfjprog won't work for example. 

     RE: JTAG Programmer (under $100, not a DK) 

    I'm not sure if there are other limitations that will make debugging difficult.

    The NRF52840-DK and NRF52833-DK both seem like the best method at the moment except for the voltage concern.

    I can't give a comment on this as I have no experience with this debugger. As earlier mentioned, we officially recommend using the SEGGER J-link with our products.

    regards

    Jared 

  • 0 in reply to Jared

    I knew there was a reason I bought a bag of level shifters a few years ago!

    I might try this later.

    Thanks

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