This is the document for SIM7600G-H LTE(4G) modem board.

Introduction

Features of this board:

• Same dimension as Raspberry Pi, easily stacked up with Raspberry Pi.

• Support all functions provided by SIM7600G-H.

• Powered by micro-USB cable or external 5.0V DC supply.

• Push-push Nano-SIM socket.

• Flip-open micro-SD socket.

• 3.5mm earphone socket and 2-pin speaker connector.

• On-board micphone.

• 40-pin connector at same place with Raspberry Pi(Not mounted).

• 20-pin connector that exports major signals of SIM7600G-H.

• SMA connectors for main/aux and GPS antenna.

• Buttons for Reset and Power function.

• 2-pin connectors for boot mode, flight mode, and power up selection.

• 2 LEDs for power and net status indication.

Features of SIM7600G-H:

• LTE Cat4 module, supports LTE-TDD/LTE-FDD/HSPA+/GSM/GPRS/EDGE etc.

• Multi-constellation GNSS receiver.

• Frequency bands:

  LTE-TDD B34/B38/B39/B40/B41.

  LTE-FDD B1/B2/B3/B4/B5/B7/B8/B12/B13/B18/B19/B20/B25/B26/B28/B66.

  UMTS/HSPA+ B1/B2/B4/B5/B6/B8/B19.

  GSM/GPRS/EDGE 850/900/1800/1900MHz.

• Data rate:

  LTE Cat4: uplink up to 50Mbps, downlink up to 150Mbps.

  HSPA+: uplink upto 5.76Mbps, downlink up to 42Mbps.

  UMTS: uplink/downlink upto 384Kbps.

  EDGE: uplink/downlink upto 236.8Kbps.

  GPRS: uplink/downlink upto 85.6Kbps.

• Control via AT commands.

• USB drivers for Windows 7/8/10, Linux.

• TCP/IP/IPv4/IPv6/Multi-PDP/FTP/FTPS/HTTP/HTTPS/DNS.

• RNDIS/NDIS/ECM.

• DTMF/Audio Playing.

• USB audio and VoLTE.

• Interface: USB 2.0, UART, USIM, PCM, MMC/SD, ADC, I2C. Antenna.

• Certifications on going: CE/RCM/FCC/IC, PTCRB/GCF, AT&T/Verizon, RoHS/REACH.

Hardware

Resource

The following figure show the resources on the board.

Number	Reference	Description
1	J12	MicroUSB connector.
2	LED2	Power LED.
3	J5	Connect this jumper to enable flight mode.
4	J4	Connect this jumper to enable power.
5	J8	NanoSIM card socket.
6	J10	Speaker connector.
7	J11	3.5mm earphone connector.
8	M1	Micphone.
9	LED1	Net status LED.
10	J14	40-pin raspberry Pi connector, NO connection with other part on this board, just for stacking.
11	J7	MicroSD card socket.
12	U1	SIM7600 module.
13	J1	Main antenna.
14	J2	Aux. antenna.
15	J9	20-pin connector, refer to the next section for its pin assignment.
16	J3	GPS antenna.
17	AN1	Power button if J4 is not connect.
18	AN2	Reset button.
19	J13	5V DC power supply connector.
20	J15	Connect this jumper to supply power from MicroUSB; DO NOT connect it while using J13 to supply power.

Connector

Most of important signals are exported by 20-pin connector J9, the following table shows its assignment.

Number	SIM7600G-H Pin	Description
1		3.3V
2		5.0V
3	4	RESET
4	3	PWRKEY
5	75	PCM_SYNC
6	76	PCM_CLK
7	73	PCM_OUT
8	74	PCM_IN
9	69	UART1_RI
10	71	UART1_TXD
11		Not connect
12	68	UART1_RXD
13	55	I2C_SCL
14	56	I2C_SDA
15	49	STATUS
16	54	FLIGHTMODE
17	46	ADC2
18	47	ADC1
19		GND
20		GND

Delivery

Delivery includes:

• 1 main board.

• 2 LTE antenna.

• 1 GNSS antenna.

• 1 MicroUSB cable.

• 4 jumpers.

Setup

Software install

Windows

1. Clone the following git repo:

   git clone https://github.com/strongtek/4G-modem.git
   

2. Go to tool/windows_usb_driver_v1.02/<your_windows_version>, copy the directory to your local driver, and right click and select Install on all the *.inf in that directory, for example:

   android_winusb.inf
   qdbusb.inf
   simfilter.inf
   simgnddusb.inf
   simmdm.inf
   simser.inf
   simwwan.inf
   

   You will see "The operation completed successfully." message box after each driver is installed.

3. You will see the following devices in the Device Manager of Windows, after install the drivers and connect hardware.

   • Modems

     • SimTech HS-USB Modem 9001

   • Network Adapters

     • SimTech HS-USB WWAN Adapter 9001

   • Ports(COM & LPT)

     • SimTech HS-USB AT Port 9001 (COM*)

     • SimTech HS-USB AT Audio 9001 (COM*)

     • SimTech HS-USB AT Diagnostics 9001 (COM*)

     • SimTech HS-USB AT NMEA 9001 (COM*)

   • Universal Serial Bus controller

     • SimTech HS-USB Composite Device 9001

   The * in the COM port number will depend on your system.

4. Install a serial port console application that you prefer, for example MobaXterm from the following URL:

   https://mobaxterm.mobatek.net/download.html
   

Ubuntu

For the latest Ubuntu 24.04 LTS version, you don't need to install additional drivers for this module.

But you may like to install certain serial console application, such like minicom:

sudo apt install minicom

If your system has no other USB to serial convertor, the /dev/ttyUSB1 would be the NMEA port, and /dev/ttyUSB3 would be the port for entering AT command.

RaspberryPi OS

For the latest RaspberryPi OS version, you don't need to install additional drivers for this module.

But you may like to install certain serial console application, such like minicom:

sudo apt install minicom

If your system has no other USB to serial convertor, the /dev/ttyUSB1 would be the NMEA port, and /dev/ttyUSB3 would be the port for entering AT command.

Hardware connect

You may skip certain steps according to your needs.

• NanoSIM: insert NanoSIM card to J8.

• MicroSD: insert a MicoSD card to J7 on the bottom side.

• Speaker: connect a speaker to the 2-in 2.54mm connector J10.

• Earphone: connect to 3.5mm earphone socket J11.

• Antenna: Connect 4G antenna to main and aux antenna SMA socket J1, J2.

• GNSS: Connect GNSS antenna to SMA socket J3.

• PWRKEY jumper: if you want to power up by default, connect a jumper to J4.

• Power: Most of USB host port can be used to supply this module.

  If you want to power the module with USB cable, connect jumper J15, and leave the DC connector J13 unconnected.

  If your USB host port can't supply enough current to this module, leave jumpper J15 unconnected, and connect an external 5V DC supply with 5mm*2.5mm(internal pole is positive) connector to J13.

• USB: connect MicroUSB cable to host with socket J12.

After power up the module, the LED2 will be turned on.

If you leave PWRKEY jumper J4 unconnected, you have to press button AN1 PWRKEY to start the module.

If you insert a valid NanoSIM card, the NETLIGHT LED1 will start to flash after join the network.

After you've done all the hardware setup, connect to the COM port labeled with "SimTech HS-USB AT Port 9001", with the setting 115200/8/N/1 in your serial port console application, type "AT" (without quote), and you will see the module returns "OK".

AT
OK

Usage

This chapter will list some common usage examples, please refer to the following document for more information:

doc/SIM7500_SIM7600 Series_AT Command Manual_V3.00.pdf

In the fowllowing code sample, the content start from '#' is comment, do NOT enter them in the serial console.

Phone call

AT+CSDVC=3      # 1: output with earphone; 3: output with speaker.
AT+CLVL=4       # range: 0~5.
ATD10086;       # replace 10086 to the number you want to call. Don't forget the ';' at the end of command.
AT+CHUP         # hang up call.

If there is a incomming call, the serial console would print "RING". In this case you can answer with command:

ATA

Short message

Send a message:

AT+CMGF=1                                       # set short message to TEXT mode
AT+CMGS="10086"                                 # replace 10086 to the number you want to text. serial console will return a promote '>'
>hello, this is a test from SIM7600 module.     # enter you text after '>', and press Ctrl+Z to send.

After sending the message, serial console will print '+CMGS: ', the will be the number of messages that have been send.

Read a message:

When there is a message comming, the serial console will print:

+CMTI: "SM",<number>"   # the <number> will be the number of messages that have been received.

You can use the following command to read a message:

AT+CMGR=26              # replace "26" with the <number> of the +CMTI promote.
AT+CMGD=26              # delete the message.

Position information

AT+CGPS=1               # enable GPS.
AT+CGPSINFO             # get GPS fixed position information
AT+CGPS=0               # disable GPS.

Note:

• It takes about 10 or more seconds before AT+CGPSINFO can get position information after AT+CGPS=1.

• GPS antenna should be placed out door.

• You can also get position information from the serial port labled "SimTech HS-USB AT NMEA 9001 (COM*)".

Access MicroSD card

The MicroSD card should format with FAT32.

AT+FSCD=D:                      # select current directory.
AT+FSLS                         # list directories/files in current directory.
AT+CFTRANTX="D:/test.txt"       # display file content.

Play sound

AT+CSDVC=3                      # 1: output with earphone; 3: output with speaker.
AT+CLVL=4                       # range: 0~5.
AT+CCMXPLAY="D:/sound.mp3",0,0  # play D:/sound.mp3.
AT+CCMXSTOP                     # stop playing.

Connect to internet(Windows)

If you install driver correctly and disable other internet connections on your computer, the Cellular adapter should be used for internet access.

Make sure it is enabled in "Control Panel->Network and Internet->Network Connections->Cellular".

Connect to internet(Ubuntu)

1. Click on the upper-right corner of the Ubuntu desktop, and then click on the gear button to open the Ubuntu settings.

   

2. In the "Network" section, disable the wired connections.

3. In the "Mobile Network" section, enable "Mobile Network" and "Mobile Data".

   

4. Then you can access internet with this module.

Connect to internet(Raspberry Pi)

1. Click on the upper-right coner of the Raspberry Pi OS desktop, and then click "Advanced Option->Edit Connections...".

   

2. Click "+" in the "Network Connections" dialog, and then select "Mobile Broadband" in the list.

   

3. Click "Next" in the "Set up a Mobile Broadband Connection" step.

   

4. Select "My provider uses GSM technology(GPRS, EDGE, UMTS, HSPA)" in the "Choose your provider" step, and click "Next"

   

5. Enter the APN of your service provider, you may find this information in your phone or by searching on the internet. And then click "Next".

   

6. Confirm your settings, and then click "Next".

   

7. Enable "Connect automatically with priority", and click "Save".

   

8. You will be able to use this module to access internet, after disable other wired and WiFi connection.

SSH to a host using SIM7600G-H networking with private IP address

In most cases, mobile ISP will assign a private IP address to your LTE modem. Your host can use this private IP address to access the internet, but you can't make other hosts connect to your host directly.

If this is the case, you may use SSH reverse tunnel to access your host from other hosts.

First, you need a SSH server with public IP address, that your host can login.

This server might be a cloud server with static public IP address, or it can be another computer in your house with dynamic public IP address.

In the later case, you may want to setup a DDNS to access your in-house server with a domain name, instead of the changable dynamic IP.

Here is the settings on the SSH server:

sudo vi /etc/ssh/sshd_config

Search "GatewayPorts" and "AllowTcpForwarding" in the config file, and make the lines like:

AllowTcpForwarding yes
GatewayPorts yes

After saving the sshd_config file, restart the SSH server.

sudo systemctl restart ssh

Then, you need to do some setup on your host:

1. Generate key files, and copy the public key to SSH server, this will make your host login into the SSH server without entering password everytime.

   ssh-keygen
   ssh-copy-id <ssh_server_user_name>@<ssh_server_address>
   

2. Make a quick test:

   ssh -nNTv -R 0.0.0.0:2222:localhost:22 <ssh_server_user_name>@<ssh_server_address>
   

   Then you can try to access your host from the server:

   ssh -p 2222 <your_host_user_name>@localhost
   

   You can also login into your host from other hosts, not only from the SSH server:

   ssh -p 2222 <your_host_user_name>@<ssh_server_address>
   

   If your SSH server is located in your house, make sure open 2222 and route it to your SSH server. This is usually done in the "Virtual server" setting page of your router.

3. Install autossh in your host, and make it run at startup.

   sudo apt install autossh
   sudo vi /etc/default/autossh
   

   In the /etc/default/autossh, entering the following text:

   AUTOSSH_POLL=60
   AUTOSSH_FIRST_POLL=30
   AUTOSSH_GATETIME=0
   AUTOSSH_PORT=22000
   SSH_OPTIONS="-N -R 2222:localhost:22 <ssh_server_user_name>@<ssh_server_address>"
   

   Create a systemd setting file for autossh service:

   sudo vi /etc/systemd/system/autossh.service
   

   In the /etc/systemd/system/autossh.service, entering the following text:

   [Unit]
   Description=autossh
   Wants=network-online.target
   After=network-online.target
   
   [Service]
   Type=simple
   User=<your_host_user_name>
   EnvironmentFile=/etc/default/autossh
   ExecStart=/usr/bin/autossh $SSH_OPTIONS
   Restart=always
   RestartSec=60
   
   [Install]
   WantedBy=multi-user.target
   

   Start and enable the autossh service:

   sudo systemctl daemon-reload
   sudo systemctl start autossh
   sudo systemctl enable autossh
   sudo reboot
   

   After reboot, you may check autossh is running by:

   sudo systemctl status autossh
   

   Now, you can SSH to your host from any hosts that can access the SSH server:

   ssh -p 2222 <your_host_user_name>@<ssh_server_address>
   

   Sometimes, your host may fail to make reverse tunnel, that might because the port number is used on the SSH server. Just kill the process that use the port number and retry.

   This section is mainly copied from https://www.jeffgeerling.com/blog/2022/ssh-and-http-raspberry-pi-behind-cg-nat, thanks Jeff!