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nRF5280 PDK Floating VDD_nRF_SENSE

sas

Hi,

Suddenly I can not connect to my nRF5280 PDK (PCA10056 0.11.0 2018.3)

1. I tried using JLinkExe and also SES, the same result, I got error "Can not connect to JLink via USB". All LEDS off.
2. Double cheking all switch, it was correct as it worked before. I am using linux, so I did "lsusb" but the PDK did not show up on lsusb output.
3. Accidentally I switch on SW10 and then I didn't know how LED5 was on. I run lsusb on the terminal which gave me output "segger", which is correct.
4. JLinkExe and SES can connect to interface MCU, but can not connect to target.

I switch off SW10, measured VSENSE_SW_OUT voltage, it showed 1.5V. This is interesting as I believe it should be around 3V as it is connected to VDD to power up the board.
Measuring VSUPPLY I got 2.89V, which is close to 3V. I suspected something wrong with U17. So I shorted SB39 and viola... the system run as expected. I can connected to SES and JLinkExe, also I can go to BOOTLOADER MODE and download blinky firmware via SES.


I concluded something was wrong with U17. I dig deeper, and found VDD_nRF_SENSE was floating if SW9 was in VDD position and SW10 was in OFF posisition.

I could be wrong here, could you please verify my finding?

Thank you,
-sas

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  • 0

    Ketiljo,

    SW10 is ON:
    1. Yes you were correct, there is no power to nRF52840. But Interface MCU is still powered. This is the expected behavior I think.

    VDD_nRF_SENSE is floating:
    1. Unfortunately I don't have the right tool to install R88. But I confirm that when I shorted both pad of R88, my laptop can communicate with the PDK smoothly., I can detect the board using lsusb command, I can download the code to nRF5280 chip.
    Shorting R88 pads means pull Q2 gate low, on which pull U17_ENABLE high and at the same time pull U16_ENABLE low. No doubt add R88 should fix VDD_nRF_SENSE floating.
    2. I believe this is not a good practice to left Q82 gate, which is VDD_nRF_SENSE, floating. If it is, then why nordic didn't populate R88? I saw some thread setters asking why suddenly their computer can not detect PDK. I conclude populate R88 is the solution to their problem. Cmiiw.

    Thanks,

Reply
  • 0

    Ketiljo,

    SW10 is ON:
    1. Yes you were correct, there is no power to nRF52840. But Interface MCU is still powered. This is the expected behavior I think.

    VDD_nRF_SENSE is floating:
    1. Unfortunately I don't have the right tool to install R88. But I confirm that when I shorted both pad of R88, my laptop can communicate with the PDK smoothly., I can detect the board using lsusb command, I can download the code to nRF5280 chip.
    Shorting R88 pads means pull Q2 gate low, on which pull U17_ENABLE high and at the same time pull U16_ENABLE low. No doubt add R88 should fix VDD_nRF_SENSE floating.
    2. I believe this is not a good practice to left Q82 gate, which is VDD_nRF_SENSE, floating. If it is, then why nordic didn't populate R88? I saw some thread setters asking why suddenly their computer can not detect PDK. I conclude populate R88 is the solution to their problem. Cmiiw.

    Thanks,

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