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Nordic Case Info
  • Case ID: 298876
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issues when flashing a custom board using nrf52833dk debug port P19

George Shaker

test setup

the custom board schematic

we tried to flash the custom board with the beacon sample here https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/samples/bluetooth/beacon/README.html

Connect debug out header P19 on DK to jtag-style connector on custom board. Connect custom board to power supply.

Testing as follows:

1.Program the 52833 chip on the dk without the connection above

Result:  success, DK beacons as expected

2.Program the 52833 chip on the dk with the connection above, but do not power the custom board

Result: success, DK beacons as expected. Custom board does not beacon as it is not powered.

3.Program the 52833 chip on the custom board with connection above and power.

Result: DK does not beacon, setup programs custom board only. Successfully program the custom board with no errors in VSCode when connecting or flashing. However, board is till not beaconing at all.

The VS code message for the third test

We then examined the voltage of the chip

Following measurements were done:

Measurement

DK Result

Custom Board Result

Voltage at DEC1

1.1 V

0.75V

Voltage at Vbus

0V

< 0.001V

Following these results, capacitor C24 in our custom board was removed. No difference in measure Voltage was observed. Custom board is still not functional.

Question:

1. did we have a correct setup to flash the custom board

2. what could be the reason that Voltage at DEC1 is not correct on our custom board

Thank you for reading through this problem.

Parents
  • 0

    Hi Jared,
    Thank you for your response. Please see the full schematic and layout: http://surl.li/duitk

    Thanks

  • 0 in reply to George Shaker

    Hi,

    EDIT:

    I just remembered that you didn't have the LFXO crystal. Have you remembered to configure the nRF52833 to use the internal RC oscillator instead?

    Could you add CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y to the prj.config file? 

    Could you also address my question in my last reply:

    Jared said:
    Have you tuned the device? It might be that the device is advertising, but that it's difficult to see the advertising because the antenna hasn't been tuned. 

    Could you share the full part number and datasheet of your HFXO crystal?

    regards

    jared

  • 0 in reply to Jared
    Jared said:
    Could you add CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y to the prj.config file? 

    Adding CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y to the config file does not seem to fix the issue. The board is still not beaconing, and is not viewable on the nRF Connect mobile application. 

    Jared said:
    Have you tuned the device? It might be that the device is advertising, but that it's difficult to see the advertising because the antenna hasn't been tuned. 

    The custom board was flashed and powered up at the DC input at J8 with a 5V-3.3V power adapter. We tested the transmit power at the SWF connector J5 on the board (oriented as shown to measure at the point closest to the nordic chip) to bypass potential issues with antenna tuning. The following results below are seen at the BLE advertising channels. Despite these results, we cannot see the device beaconing on the nRF Connect mobile application. 

    When measuring the DK at the SWF connector J1, we got the following result below at the BLE advertising channels. After removing the measurement probe, we can also see the DK advertising

    Jared said:
    Could you share the full part number and datasheet of your HFXO crystal?

    To answer your question about the crystal, we are using ECS-320-8-37B-7KM-TR.

    Additional details: 

    - RF matching network for custom PCB and DK after nordic chip are identical.

    - Stackup for custom PCB and DK are identical.

  • 0 in reply to George Shaker

    Hi,

    Some of the signal will be radiated directly out from the radio (not through the ant path), can you connect an antenna to the signal analyzer and put it close to the radio, and see if you can measure the radiated signal from the radio?

    regards

    Jared 

  • 0 in reply to Jared

    We measured the radiated signal using a spectrum analyzer as shown in the setup, and a single antenna tuned for 2.45 GHz (confirmed using VNA).

    After a few measurements, the DK was advertising at a power around -47 dBm. See setup and results below. We added a connector to J5, as shown, to disconnect the trace antenna and consider only the radio output. Even with this setup, DK is still beaconing and is visible on the nRF connect mobile application (which shows around -90 dBm).

    The custom PCB has a transmit power of around -50 dBm at the BLE advertising channels. See setup and results below; results are similar in terms of signal power on the spectrum analyzer. Note, there is no antenna attached to the custom PCB, this is purely the signal from the radio, not the ant path. 

    Yesterday, when we measured the power from the ant path, the custom PCB showed a magnitude of around -70dB.

Reply
  • 0 in reply to Jared

    We measured the radiated signal using a spectrum analyzer as shown in the setup, and a single antenna tuned for 2.45 GHz (confirmed using VNA).

    After a few measurements, the DK was advertising at a power around -47 dBm. See setup and results below. We added a connector to J5, as shown, to disconnect the trace antenna and consider only the radio output. Even with this setup, DK is still beaconing and is visible on the nRF connect mobile application (which shows around -90 dBm).

    The custom PCB has a transmit power of around -50 dBm at the BLE advertising channels. See setup and results below; results are similar in terms of signal power on the spectrum analyzer. Note, there is no antenna attached to the custom PCB, this is purely the signal from the radio, not the ant path. 

    Yesterday, when we measured the power from the ant path, the custom PCB showed a magnitude of around -70dB.

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