nrf9160 custom HW SIM connectivity issue

[Muhammad Usman]

Dear Nordic devzone community,

I am using nrf connect SDK version 1.8.0 for the asset tracker and 2.0.2 for AT client. IDE is Vscode Studio.

I have designed a custom board using nRF9160 and I am able to send and read out certain AT commands which confirms to me that most of the embedded part of the design functions fine.

1)Custom Board is replying to the AT commands as mentioned in the attached image but not responding to the AT+CPIN command to recognize the SIM. I have attached the schematic of the custom board as well.

2084.nrf52820_sensor_NORDICV2.pdf

A few observations while debugging the HW 

a)1.8V output to SIM card is not provided by NRF9160(using the asset tracker FW, which is provided to the DK)

b)What we left open is DETECT pin from nrf9160. But the 1.8V output pin from NRF9160 is still connected to the SIM card connector.

I followed the following links 

 Programming/Debugging nRF9160 SiP on custom board 

https://devzone.nordicsemi.com/f/nordic-q-a/58055/nrf9160-custom-board---connect-uart-and-send-at-commands/238646#238646

 nrf9160 custom board AT client not working 

 Getting HWID nRF9160 custom HW board and using LTE LINK monitor with custom Hardware 

[Jared]

Hi,

I took at quick look at your  nRF52820 as well and have some comments:

nRF52820:

1. If USB interface is not used then VBUS can be grounded and only VDDH supplied
2. Some of the pins that you have used for serial communication is marked as low frequency/low drive in the PS. Consider re-assigning them.
3. C19 can be omitted.

nRF9160:

regarding your SIM 1V8 issue. The schematic looks ok. What voltage do you measure on the other SIM pins?

Could you share the PCB layout files as well?

regards

Jared