How to Interface nRF9160 with external MCU for nb-IOT control using AT commands?

Hello,

please suggest if there is any reference example available for this purpose.

you can use the SLM sample to achieve this functionality. It should work with NB-IoT as well I believe.

Hi, Hakon

Thanks for your reply. 

SLM sample which you have suggest, how should I upload or compile for development board, as I am new here.

Still I am not aware where should I connect UART pins of DK board to External MCU for AT command control.

Looking forward to hearing from you.

Thanks

Ashvin Makwana said:

SLM sample which you have suggest, how should I upload or compile for development board, as I am new here.

If you are new to developing with the nrf9160 you should probably start be reading this. You need to download the SDK and command line tools, before you can start developing.

Ashvin Makwana said:

Still I am not aware where should I connect UART pins of DK board to External MCU for AT command control.

If you are using an external MCU you should uncomment the two lines in prj.conf located in the application folder

#CONFIG_SLM_CONNECT_UART_2=y
#CONFIG_UART_2_NRF_HW_ASYNC_TIMER=2

and comment CONFIG_UART_0_NRF_HW_ASYNC_TIMER=2. Then you can check the rx and tx pins in nrf9160dk_nrf9160_ns.overlay located in the application folder. For uart2 this should be P0.11 and P0.10 respectively. You can change the pins if you want, you just need to set different values in the nrf9160dk_nrf9160_ns.overlay file.

Hi Hakon

Thanks again for your support. 

I have read the above documents and updated pre-built firmware nb-IOT in DK board. 

I have tested the AT commands over USB connection which are available on DK. 

Now, as per your suggestion I have followed  your links and tested some example (led blink, Hello world)on board from sample.

I have checked that SLM application which you have shared and it would help me, but I  am not  able to find that SLM example available in SDK.

how can I import SLM example that you share into visual studio code? could you please help me on this? 

Thanks   

It's located in nrf/applications sub directory, not nrf/samples.

Hi Hakon

Thanks a lot for your help.

I am able to find nrf/application and built it successfully, but I am getting warnings more than 50. I don't know they are for.

I have flash the file into DK board and able to test AT commands on over USB with pc.

Now, for MCU purpose, need to changes those line but not able find this lines , 

"CONFIG_UART_0_NRF_HW_ASYNC_TIMER=2 ,

#CONFIG_SLM_CONNECT_UART_2=y, 

#CONFIG_UART_2_NRF_HW_ASYNC_TIMER=2" in file.

Attaching the prj.conf file,

Thanks 

Hi Hakon

Thanks a lot for your help.

I am able to find nrf/application and built it successfully, but I am getting warnings more than 50. I don't know they are for.

I have flash the file into DK board and able to test AT commands on over USB with pc.

Now, for MCU purpose, need to changes those line but not able find this lines , 

"CONFIG_UART_0_NRF_HW_ASYNC_TIMER=2 ,

#CONFIG_SLM_CONNECT_UART_2=y, 

#CONFIG_UART_2_NRF_HW_ASYNC_TIMER=2" in file.

Attaching the prj.conf file,

Thanks 

My bad, it's in boards/nrf9160dk_nrf9160_ns.conf. This was changed recently.

Hi Hakon,

Thanks for your help and sorry for late reply. 

I will look into your referral  links and update you soon.

Hi Hakon,

Thanks for your support.

Now, I am able to connect with  board with UART2 on pin P0.10, P0.11. 

Is There any other pins are available for UART2 , expect P0.10, P0.11?  If Yes, can you please share here?

can I use any other UART for same purpose? 

Thanks & Regards,

Ashvin Makwana

Ashvin Makwana said:

If Yes, can you please share here?

You can see most GPIO pins that are not being used by the DK already. For more information you can look here.

Hi

Thanks for your reply. 

I am able change UART2 pins to another pins and tested with at commands.  UART communication is working now.

Now, I am trying to detect the SIM card in custom board with AT commands, but getting error in response. I think SIM_1V8 voltage is not getting generated from nRF91.

I am not using eSIM.

Test case : 

Measuring Voltage on SIM_1V8 (Pin 49) in DK : 

1) When sim card is connected with DK board and sending AT commands AT+CFUN=1, I am getting 1V8 on P30.

2) When sim card is not connected with DK board and sending same commands, I am not getting 1V8 on P30.

3) Only connecting sim card but not getting voltage on P30.

Is there any SIM_DET pin is being used inside DK board? which is being used for sim inserted into  socket or not.

I have checked layout of DK board for sim detect but did not found any pin which is connected to sim socket.

I am following this ref links for sim interface. 

NOTE: SIM_1V8 is not getting generated in custom board.

Custom board AT test. 

AT 

OK
AT+CFUN=1

OK
AT+CFUN?

+CFUN: 1
OK
AT+CPIN?

ERROR