Sierra EM7455 on NRU-50

This guide helps you install Sierra EM7455 or EM7430 on NRU-50

0. Prerequisite

• By default, you can use Sierra EM7455 on the M.2 B key of NRU-50.

• If you would like to use Sierra EM7455 on mPCIe of NRU-50, please remember to use a mPCIe to M.2 B key adapter card with SIM slot.

• You need a SIM card and antennas to complete the full settings

• You need an Ethernet connection to download related packages

• If your Sierra EM7455 required specific firmware, we highly recommend you flash the firmware on a Windows machine. We are still asking Sierra for the right tool to flash Sierra in Linux. You can find .exe for corresponding firmware update on the Sierra website https://source.sierrawireless.com/resources/airprime/minicard/74xx/airprime-em_mc74xx-approved-fw-packages/

1. Setup without SIM Card

Step 1-0. QUICK INSTALLATION !!

Meanwhile, I have prepared a quick script to finish the whole settings of "1. Setup without SIM Card."

wget https://github.com/qshiwu/NRU-Public/raw/main/SierraEM7455_nru50.tar.gz
tar -xzvf SierraEM7455_nru50.tar.gz
cd SierraEM7455_NRU50/
sudo bash ./00_install_SierraEM7455.sh

After the above scripts, reboot your computer, you can type the following command, to check if you have installed the driver successfully.

sudo mmcli -S
sudo mmcli -L

You can check the SierraEM7455 status by sudo mmcli -m 0

/org/freedesktop/ModemManager1/Modem/0 (device id 'f317897450434595a9e80c424d598be473f950e1')
  -------------------------
  Hardware |   manufacturer: 'Sierra Wireless, Incorporated'
           |          model: 'EM7455'
           |       revision: 'SWI9X30C_02.24.05.06 r7040 CARMD-EV-FRMWR2 2017/05/19 06:23:09'
           |   H/W revision: 'unknown'
           |      supported: 'gsm-umts'
           |        current: 'gsm-umts'
           |   equipment id: '359073XXXXXXXXX'
  -------------------------
  System   |         device: '/sys/devices/3610000.xhci/usb2/2-3/2-3.3'
           |        drivers: 'GobiSerial driver'
           |         plugin: 'Generic'
           |   primary port: 'ttyUSB2'
           |          ports: 'ttyUSB0 (qcdm), ttyUSB2 (at)'
  -------------------------
  Numbers  |           own : 'unknown'
  -------------------------
  Status   |           lock: 'unknown'
           | unlock retries: 'unknown'
           |          state: 'failed'
           |  failed reason: 'sim-missing'
           |    power state: 'on'
           |    access tech: 'unknown'
           | signal quality: '0' (cached)
  -------------------------
  Modes    |      supported: 'allowed: 3g, 4g; preferred: none'
           |        current: 'allowed: any; preferred: none'
  -------------------------
  Bands    |      supported: 'unknown'
           |        current: 'unknown'
  -------------------------
  IP       |      supported: 'ipv4, ipv6, ipv4v6'
  -------------------------
  SIM      |           path: 'none'

  -------------------------
  Bearers  |          paths: 'none'

Then, you can jump to "Step 2-2. Add the New Mobile Broadband" to complete the settings related to the SIM card.

2. Setup with SIM Card

Step 2-1. Please finish the above step in "1. Setup without SIM Card"

Step 2-2. Add the New Mobile Broadband

If the "New Mobile Broadband Connection" GUI is missing, execute nm-connection-editor in the terminal instead.

Follow the below step-by-step guide to add new mobile broadband based on your provider.

Step 2-3. Make NRU Connect to 4G Automatically

Step 2-4. Change the SIM Slot

The M.2 B key of NRU-50 has two micro SIM slots. When you are using Sierra EM7455 in M.2 B Key

• USIM 0 - the one on the PCBA

• USIM 1 - the one on the front panel

Step 2-4-1. Find the Primary Serial Port of Sierra EM7455

You can change Sierra EM7455 settings by an internal serial port, which is /dev/ttyUSB2 . You can confirm your serial port location by calling...

sudo mmcli -S
sudo mmcli -L

## update 0 with the device id in the mmcli -L result
sudo mmcli -m 0

Step 2-4-2-0. Make sure /dev/ttyUSB2 is Accessible

If you're unable to open /dev/ttyUSB2 of SierraEM7455 to send AT commands, you can determine which process is using /dev/ttyUSB2 by executing the following:

# Check which process occupying /dev/ttyUSB2
sudo ps auxww | grep ttyUSB2 

If the LTE is already connected to the network, it's common for /dev/ttyUSB2 to be occupied by pppd. To stop pppd from using /dev/ttyUSB2, first ensure that the "Connect to Network Automatically" option is disabled in nm-connection-editor.

Afterward, you can kill the pppd process by the following:

sudo pkill pppd
# Wait 1 second
# Confirm pppd is not respawn
sudo ps auxww | grep ttyUSB2 

Finally, you can access /dev/ttyUSB2 by

sudo minicom -b 115200 -D /dev/ttyUSB2

Step 2-4-2. Use AT Commands to Config EM7455

There are two common serial port tools, putty and minicom, to send AT commands to EM7455. The former is easier for interactive testing; the latter is easier to execute by script.

You can find the official AT commands doc [here]. The following are some commonly used commands.

## Show current Sierra Fireware / ID Information
ATI

# Manufacturer: Sierra Wireless, Incorporated
# Model: EM7455
# Revision: SWI9X30C_02.24.05.06 r7040 CARMD-EV-FRMWR2 2017/05/19 06:23:09
# MEID: 35907306078059
# IMEI: 359073060780594
# IMEI SV: 12
# FSN: LF815573310110
# +GCAP: +CGSM


## Enable dual SIM cards support
AT!ENTERCND="A710"
AT!CUSTOM="UIM2ENABLE",1

## Show currently enabled customizations.
AT!CUSTOM?

## Check the USIM in use
AT!UIMS?

## Change to USIM 0
AT!UIMS=0

## Change to USIM 1
AT!UIMS=1

If Sierra received your command successfully, you will see a OK response from Sierra.

Step 2-4-2-1. AT Commands with Putty

You can install Putty by:

sudo apt install -y putty

If your serial port is locked, please disconnect your 4G connections, pkill putty and pkill minicom

Remember to open putty with sudo to get the necessary permission.

sudo putty

Enable the local echo to get a better user experience while typing the AT commands. (Otherwise, you won't see what you typed in Putty)

Step 2-4-2-2. AT Commands with Minicom

If your serial port is locked, please disconnect your 4G connections, pkill putty and pkill minicom

You can install minicom by

sudo apt install -y minicom

Change to USIM 0

sudo echo 'send ATI
sleep 1
send AT!ENTERCND=\"A710\"
sleep 1
send AT!UIMS=0
sleep 1
send AT!UIMS?
! pkill minicom
' > script.txt

sudo minicom -b 115200 -D /dev/ttyUSB2 -S script.txt

Change to USIM 1

sudo echo 'send ATI
sleep 1
send AT!ENTERCND=\"A710\"
sleep 1
send AT!UIMS=1
sleep 1
send AT!UIMS?
! pkill minicom
' > script.txt

sudo minicom -b 115200 -D /dev/ttyUSB2 -S script.txt

Enable Dual SIM Card

sudo echo 'send ATI
sleep 1
send AT!ENTERCND=\"A710\"
sleep 1
send AT!CUSTOM=\"UIM2ENABLE\",1
! pkill minicom
' > script.txt

sudo minicom -b 115200 -D /dev/ttyUSB2 -S script.txt

Disable Dual SIM Card

sudo echo 'send ATI
sleep 1
send AT!ENTERCND=\"A710\"
sleep 1
send AT!CUSTOM=\"UIM2ENABLE\",0
! pkill minicom
' > script.txt

sudo minicom -b 115200 -D /dev/ttyUSB2 -S script.txt