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programming nrf51822 in low voltage mode using level translator

michel

I'm trying to program a nrf51822 custom board using the SWD interface of the nrf51 DK. The board is using the low voltage configuration.

I'm not duplicating this question because I think that I'm showing a different problem here and I'm showing the logic level translator configuration.

I'm connecting everything as follows:

  • SWDIO on nRF51 connects to SH_SWDIO (pin #4) on P20 (green wire)
  • SWDCLK on nRF51 connects to SH_SWDCLK (pin #5) on P20 (orange wire)
  • VDD on nRF51 connects to SH_VTG (pin #3) on P20 (cyan wire)
  • GND on nRF51 connects to SH_GND_DETECT (pin #8) (purple wire)

image description

When I try to flash program the board, the keil throws this error:

image description

When I disconnect the ground detect of P20 the keil programs the DK board.

My question is: What am I doing wrong? Why it doesn't work as I expect?

Thank you in advance.

Best Regards.

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  • 0

    I'm not able to test the setup since I don't have a logic level translator, but can you try to set SH_VTG to the 3.3V instead of the 1.9V? Since that is the voltage the debugger is seeing.

    Are you sure the transistors are able to keep up with the SWD speed? Maybe try to set it to 5kHz in Keil.

    And as Monpetit suggested, make sure your voltage divider is able to supply enough current. The chip draws several milliamps while flashing, so make sure the voltage drop is not too high.

    Let me know what you find out, and meanwhile I will try to get my hands on a level translator.

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  • 0

    I'm not able to test the setup since I don't have a logic level translator, but can you try to set SH_VTG to the 3.3V instead of the 1.9V? Since that is the voltage the debugger is seeing.

    Are you sure the transistors are able to keep up with the SWD speed? Maybe try to set it to 5kHz in Keil.

    And as Monpetit suggested, make sure your voltage divider is able to supply enough current. The chip draws several milliamps while flashing, so make sure the voltage drop is not too high.

    Let me know what you find out, and meanwhile I will try to get my hands on a level translator.

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