Issue with UART communication on nRF52840 DK (v3.0.0)

[h.omer]

I recently purchased an nRF52840 DK (v3.0.0) to use with my custom nRF9160 boards for firmware loading, debugging, and loading certificates for nRF Cloud. While I can successfully load firmware and debug, I'm encountering an issue when trying to use the UART output (P0.06/P0.08) for certificate loading.

The problem is that the RX pin on the DK board is constantly high, preventing it from detecting signals coming from my custom board. This is hindering my ability to load certificates for nRF Cloud.

Specific details:

1. Development Kit: nRF52840 DK (v3.0.0)

2. Purpose: Loading certificates to custom nRF9160 boards for nRF Cloud

3. Issue: UART RX pin (P0.06) and VCOM_RxD(TP2) on the DK is constantly high

4. Impact: Unable to receive data from the custom board, preventing certificate loading

I've previously used an older version of this board without any issues. Firmware loading and debugging are working fine on the new board, but the UART communication problem is preventing me from completing my development process.

Could you please provide guidance on how to resolve this issue? I need to be able to use the UART communication for certificate loading.

Thank you for your assistance.

Best regards,

H.Ömer Gürsoy

[h.omer]

Hello,

I just wanted to follow up to check if there are any updates regarding my previous message.

Thank you, and I look forward to hearing from you.

Best regards,
H.Ömer Gürsoy

[Priyanka]

Hi,

Since this is the newer revision, it will be using the nRF5340 SoC as the interface MCU compared to the SEGGER chip on your previous revision DK. You can see here that in the pull up is enabled for the pins by default. But I am not sure if this is the issue, because then you should have had the problem when uploading the firmware and debugging.

UART RX pin (P0.06)

The P0.06 is the TX and P0.08 is the RX. Did you interchange them?

Also, please upload the errors that you see when you try to load the certificates so that we can try to check the problem in detail.

-Priyanka