Integrating nrf52 with BG95(Quectel Modem)

[Ukhan]

Hi,

Has anyone integrated an nrf52 DKboard with BG95? I’m having a trouble in the integration. Sending the “AT” over uart and get an “OK”.
I’ve translated the uart voltage level from 3.3 to 1.8V but the modem still is not responsive.
This seems pretty trivial, but any guidance would be appreciated

[Edvin]

Hello,

So the BG95 responds OK after sending the AT command? How is it none responsive then?

BR,

Edvin

[Ukhan]

Sorry for my poor English, that's not what I intended to imply. I wasn't receiving OK for AT.

Anyway, there was a hardware configuration which was required, the voltage level of the uart had to be translated from 3.3V to 1.8V.

It's working now, wasn't so much of an issue for Nordic platform anyway.

Thanks for responding though. The ticket can be closed.

Regards,

[ErDarshan]

Hello,

I am facing the same issue. I have NRF52840-DK and BG95 EVM. I am using GSM modem example code of zephyr.

I have connected NEF UART to 1.8V UART of BG95 and not able to see any response. I tried with connecting to 3V UART of BG95 but issue is still there.

Can you guide how you resolve the issue and what changes you have made?

[Ukhan]

Hopefully these links help you in having "Ok" by sending "AT" to the modem.

https://forums.quectel.com/t/can-we-use-voltage-translator-ic-on-umts-lte-evb-to-step-down-voltage-from-3-3-to-1-8-v-for-communication-between-external-mcu-nrf52-and-bg95-module/7863

https://forums.quectel.com/t/nrf52-with-bg95m2/7772

That's how I solved the issue at my end.

You have to remove some resistors from the EVM if you've the same h/w as I did.

[ErDarshan]

Hi,

Thank you for your response.

Have you used J806 of BG95 evm? And have you used 1.8V RX/TX or 3V? I have Quectel modem UMTS&LTE EVB_V2.2.
Other than this, anything we need to do from NRF52 side? I have configured power source as Vdd.

[Ukhan]

I think your h/w is the same as I had.

Did you go through the details shared in the links I shared?

That's what I did - it makes use of the input voltage of 3.3V but then makes a voltage translation via the IC on the UMTS&LTE EVB.

[ErDarshan]

Hi,

Yes, I have gone through the links and they suggest doing minor rework on BG95 EVM.

I am confused in connection with BG95 to NRF52. Have you connected through MAIN UART or with Test points of 3V/1.8V?

[Ukhan]

I don't quite follow your question, and I don't have the h/w with me either.

However I've attached an image.
The area in red rectangle shows the slots to be utilized for driving the uart lines of BG 95 from NRF52. (This is what is explained in the links in greater detail)

[ErDarshan]

Thanks. Got information which I needed and it's working now.