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

[Ashvin Makwana]

Hi,

I have this development board https://www.nordicsemi.com/Products/Development-hardware/nRF9160-DK .  I would like to use development board as nb-IOT modem and other MCU to control it send data over  nb-IOT modem using AT commands, it is possible to do this? 

I have tested this board with nRF desktop software using 2G network and AT command. 

As of now, I don't  have nb-IOT sim card available to test, so not able to test. 

Query targeting MCU interface : 

1) Which RX, TX pin of nRF9160 would be used to control over MCU? 

2) Which SDK should I use for AT command functionality? 

3) what other changes are needed to work with nb-IOT network ? 

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

Any help will be appreciated. 

Thanks & Regards,

Ashvin

[Hakon]

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.

[Ashvin Makwana]

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]

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 

Fullscreen 0726.prj_conf.txt Download

#
# Copyright (c) 2020 Nordic Semiconductor ASA
#
# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
#
# General config
CONFIG_LOG=y
CONFIG_LOG_DEFAULT_LEVEL=3
CONFIG_STACK_SENTINEL=y
CONFIG_NEWLIB_LIBC=y
CONFIG_NEWLIB_LIBC_FLOAT_PRINTF=y
CONFIG_RING_BUFFER=y

# Segger RTT
CONFIG_USE_SEGGER_RTT=n
CONFIG_RTT_CONSOLE=y
CONFIG_UART_CONSOLE=n
CONFIG_LOG_BACKEND_RTT=y
CONFIG_LOG_BACKEND_UART=n

# Network
CONFIG_NETWORKING=y
CONFIG_NET_SOCKETS=y
CONFIG_NET_NATIVE=n

# Modem library
CONFIG_NRF_MODEM_LIB=y
# Align the max FD entry to NRF_MODEM_MAX_SOCKET_COUNT(8)
CONFIG_POSIX_MAX_FDS=8
# Enable below for modem trace
#CONFIG_NRF_MODEM_LIB_TRACE_ENABLED=y

# Use GPIO
CONFIG_GPIO=y
CONFIG_GPIO_NRFX=y

# UART interface
CONFIG_SERIAL=y
CONFIG_UART_ASYNC_API=y
CONFIG_NRFX_TIMER2=y

# Stacks and heaps
CONFIG_MAIN_STACK_SIZE=4096
CONFIG_HEAP_MEM_POOL_SIZE=16384
CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=4096

# Device power management
CONFIG_PM_DEVICE=y

# FOTA
CONFIG_HTTP_PARSER_URL=y
CONFIG_FOTA_DOWNLOAD=y
CONFIG_FOTA_DOWNLOAD_PROGRESS_EVT=y
CONFIG_DFU_TARGET=y
CONFIG_DOWNLOAD_CLIENT=y
CONFIG_DOWNLOAD_CLIENT_STACK_SIZE=4096
CONFIG_BOOTLOADER_MCUBOOT=y
CONFIG_IMG_MANAGER=y

# FLASH
CONFIG_FLASH=y
CONFIG_FLASH_PAGE_LAYOUT=y
CONFIG_FLASH_MAP=y
CONFIG_MPU_ALLOW_FLASH_WRITE=y
CONFIG_IMG_ERASE_PROGRESSIVELY=y

# Settings
CONFIG_SETTINGS=y
CONFIG_SETTINGS_FCB=y
CONFIG_FCB=y

# nRF Cloud
CONFIG_CLOUD_API=y
CONFIG_NRF_CLOUD_MQTT=y
CONFIG_NRF_CLOUD_FOTA=n
CONFIG_NRF_CLOUD_AGPS=y
CONFIG_NRF_CLOUD_PGPS=y
CONFIG_NRF_CLOUD_CELL_POS=y
CONFIG_NRF_CLOUD_LOG_LEVEL_INF=y
CONFIG_DATE_TIME=y
CONFIG_MODEM_INFO=y
CONFIG_MODEM_INFO_ADD_DATE_TIME=n
CONFIG_AT_MONITOR=y
CONFIG_MODEM_JWT=y
# Use "nrf-<IMEI>" as the default device_id format
# Use "<device_uuid>" as the device_id format by below
#CONFIG_NRF_CLOUD_CLIENT_ID_SRC_INTERNAL_UUID=y

#
# SLM-specific configurations
#
CONFIG_SLM_CUSTOMIZED=n
CONFIG_SLM_LOG_LEVEL_INF=y
CONFIG_SLM_EXTERNAL_XTAL=n
CONFIG_SLM_START_SLEEP=n

# nRF Cloud based location services
CONFIG_SLM_AGPS=n
CONFIG_SLM_PGPS=n
CONFIG_SLM_CELL_POS=n

# Serial DFU support
CONFIG_SLM_NRF52_DFU=n
CONFIG_SLM_NRF52_DFU_LEGACY=n

[Hakon]

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

[Ashvin Makwana]

Hi Hakon,

Thanks for your help and sorry for late reply. 

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

[Ashvin Makwana]

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

[Hakon]

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.

[Ashvin Makwana]

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

 

[Hakon]

Can you create a separate ticket for these questions? They seem to deviate a bit from the original question.