1002 RPi0 4G Cat1 EN
Keywords
Raspberry Pi Zero, Zero 2W, Cat1 4G LTE Expansion board, Nano SIM, RPi-Connect, Remote connection, Driver-free
I. Introduction
The RPi0_CAT1 is a 4G LTE expansion board measuring only 65*30mm in size. It is designed based on the Raspberry Pi Zero series (including the Zero, Zero W(H) and Zero 2W).
The expansion board comes in two versions: the USB version and the Probe version.
The Probe version: It utilizes the gold-plated test points on the backside of the Raspberry Pi Zero board for USB and power to enable peripheral expansion. In this case, the Raspberry Pi Zero's microUSB port cannot be connected to any other USB devices (otherwise the 4G module will not function).
The USB version can be used with the Raspberry Pi 3B, 4B, and 5. The expansion board uses a recessed design, which facilitates installation on top of boards like the Raspberry Pi 3B/4B/5, ensuring it does not affect the external connections of the 40-pin header.
4G Cat1 is a cost-effective module designed for medium-speed IoT applications around 10Mbps. The 10Mbps downlink and 5Mbps uplink speeds can meet the vast majority of networking and transmission needs. The CAT1 expansion board is driver-free under the official Raspberry Pi operating OS.
(To use the 4G module, the band supported by your local SIM card service provider must match the parameters of the 4G module. Therefore, please verify whether this 4G module is suitable for your area before making a purchase.)
(Note: If using the Probe version of this expansion board, the Raspberry Pi Zero will not be able to use OTG functionality. If you need to use OTG functionality, the 4G module on the expansion board will be unavailable.)
II. Hardware Spec
1) The Probe version connects to the Raspberry Pi Zero series' pogo pins to achieve power supply and communication. Powered through the Zero's MicroUSB power port. At this point, the Raspberry Pi Zero's own micro USB, the onboard USB-C port, and the 1.25mm 4-pin interface cannot be used to connect any external devices or power sources.
2) The USB version (without soldering pogo pins) communicates with the motherboard through the USB port, and power is also supplied via this USB port (5V input). The USB port is available in either Type-C or 1.25mm 4P interface, with only one being usable at a time.
3) 1*4G CAT1 LTE and a Nano SIM card slot;
4) 1*IPEX 1 connector.
5) Debug Serial Port and AT main serial port: 2.54mm-3Pin, both at 3.3V voltage level.
6) 2*LEDs: 1*STAT LED and 1*NET LED
7) The reserved BooT and reset button is on the back side reverse side.
8) Size: 65*30*6.6mm, M2.5mm mounting holes.
9) PCB: UL and ROHS certification, fire protection rating of 94V-0.
| 4G LTE | CAT1 |
| BAND | LTE-TDD: B34/B38/B39/B40/B41
LTE-FDD: B1/B3/B5/B8 |
| DATA | LTE-TDD: Max 8Mbps (DL)/Max 2Mbps (UL)
Max 6Mbps (DL)/Max 4Mbps (UL) |
| LTE-FDD: Max 10Mbps (DL)/Max 5Mbps (UL) | |
| General characteristic | 3GPP E-UART Release 13 |
| Temperature | -40℃ ~ +85℃ |
III. Work with Raspberry Pi OS
Different versions of Raspberry Pi OS have varying strategies for network management. Based on the 64-bit OS version, the results are as follows:
| OS version (64-bit) | Test results |
| 2023-02-21-bullseye | Driver-Free, No Dial-Up Required, Auto-identification, plug and play, automatic internet connection. |
| 2023-05-03-bullseye | |
| 2023-12-05-bookworm | Driver-Free, No Dial-Up Required, Auto-identification, but there may be instances of network connection failure,
and the OS requires the installation of DNS software. |
| 2024-07-04-bookworm | |
| 2024-11-19-bookworm | |
| 2025-05-13-bookworm | |
| 2025-10-01-trixie |
The Raspberry Pi Zero series boards only support 32-bit OS. The test results are as follows:
| OS version (32-bit) | Test results |
| 2023-02-21-bullseye | Driver-Free, No Dial-Up Required, Auto-identification, plug and play, automatic internet connection. |
| 2023-05-03-bullseye | |
| 2023-12-05-bookworm | |
| 2024-07-04-bookworm | |
| 2024-11-19-bookworm | |
| 2025-05-13-bookworm | |
| 2025-10-01-trixie |
3.1 USB version
The hardware platform for the operation: RPi0_2U2E expansion board (Raspberry Pi Zero dual Ethernet port expansion board) paired with Raspberry Pi Zero 2W and CAT1 module; assembly method as shown in the figure below:
Software operation:
The version of the Raspberry Pi OS is: 2023-05-03-raspios-bullseye-arm64.img.xz
You can download the Raspberry Pi OS in:
https://www.raspberrypi.com/software/operating-systems/#raspberry-pi-os-64-bit
Plug the Ethernet cables connected to the upstream router into the two Ethernet ports. After booting the OS, execute ifconfig -a, and you will see eth2, which corresponds to the 4G CAT1 interface; while eth0 and eth1 are the two 100Mbps Ethernet ports on the RPi0_2U2E Board.
At this point, we unplug the Ethernet cable and use 4G to test pinging external IP addresses and domain names, such as:
ping 220.189.255.38
ping www.mcuzone.com
Both the IP and domain were successfully pinged, indicating that the 4G CAT1 is functioning properly:
To view the 4G operation status, observe the status of the LED:
STAT LED on indicates 4G normal operation.
The NET LED indicates the network status: 1.8 seconds on and 0.2 seconds off indicates successful network registration, while 1.8 seconds off and 0.2 seconds on indicates no network registration, requiring a check of the SIM card and antenna.
3.2 Probe version
3.2.1 Preparation
The CAT1 Probe version is paired with the Raspberry Pi Zero series board. Since the Zero itself has only one USB port, which is occupied by the 4G module, it cannot connect a mouse or keyboard. Therefore, it is recommended to choose a WiFi-enabled version (such as the Zero W, Zero WH, or Zero 2W). During the OS flashing process, pre-configure the WiFi and enable SSH to further utilize the 4G functionality.
If you plan to use Raspberry Pi Zero, you can only opt for the Probe version if the OS has been fully debugged on another development board with all business logic implemented and set to auto-run on startup, and if there are no additional USB device requirements, with 4G Cat1 solely used for network access. Otherwise, the USB version is recommended.
Hardware: Please plug the power supply into the USB power port marked "PWR" on the Zero 2W. If you plug it into another USB port or the USB port on the expansion board, it will cause the 4G module to be shielded.
Wiring diagram:
The version of the Raspberry Pi OS is: 2024-07-04-raspios-bookworm-arm64.img.xz
You can download the Raspberry Pi OS in:
https://www.raspberrypi.com/software/operating-systems/#raspberry-pi-os-64-bit
(If using the first-generation Raspberry Pi Zero board, which only supports 32-bit OSs, please pay attention to the version you download.)
3.2.2 Flash OS (Setup required for WiFi connection and SSH service)
The OS is flashed onto the TF card.
For the flashing method, please refer to:
When flashing, setup the WiFi connection and SSH service:
"Edit Settings":
In the pop-up window, under the GENERAL tab, you can set the hostname, username, and password, the default WiFi connection, and the region:
Under the SERVICES tab, please set up to enable the SSH service:
After completing the settings, click "Save".
After the flashing process is complete, boot the OS using the TF card. The OS will automatically log in with the preset username and password, and connect to the predefined WiFi network (within the coverage area of the WiFi hotspot).
3.2.3 Control via SSH through WiFi
After the OS starts, if the WiFi connection is successful, the internal network IP will be displayed below the WiFi icon in the top right corner of the desktop:
You can also obtain the OS's internal IP address by checking the router's backend:
Here, we use the MobaXterm for SSH. The download link for MobaXterm is:
https://mobaxterm.mobatek.net/download-home-edition.html
Open the MobaXterm, create a new connection, select SSH, enter the IP address of the Raspberry Pi OS in the "Remote Host", and enter the login username in the "Specify username", as shown in the following figure:
Click "OK," then log in. After logging in, we can perform command-line operations on the Raspberry Pi Zero 2W using MobaXterm:
Now we check the connection status of the 4G module:
lsusb
It can be seen that the 4G module has connected.
Using ifconfig -a to check the network interfaces, it can be seen that the 4G module is identified as eth0 and has obtained an IP address:
Install the DNS switching software udhcpc, execute in the terminal:
sudo apt install udhcpc
After installation, execute:
sudo udhcpc -i eth0
This sets the default internet network card and DNS to 4G.
Both the IP and domain were successfully pinged, indicating that the 4G CAT1 is functioning properly:
3.3 How to use AT commands
Whether it's the USB version or the Probe version, the operation method for AT commands is the same. Here, we use the Probe version as an example.
Execute commands in the SSH terminal:
lsusb
Record the ID value of the 4G module: 19d1 0001
Use the following command to open the serial port, where the value after echo is the ID recorded above:
sudo modprobe option
sudo sh -c 'echo 19d1 0001 > /sys/bus/usb-serial/drivers/option1/new_id'
After execution is complete, the OS should have three additional devices: ttyACM0, ttyACM1, and ttyACM2. Input ls /dev to view:
Install minicom:
sudo apt-get install minicom
By default, the AT command serial port is ttyACM0.
Open AT Command serial port by minicom:
sudo minicom -D /dev/ttyACM0
(Note: Typically, three ports (ttyACM0 to ttyACM2）will appear. In general, the AT port is ttyACM0 under most OSs. If that doesn't work, you may try other ports such as ttyACM2. If multiple USB-to-serial devices are present, further attempts will be needed until the correct AT port is identified.)
The first time you enter an AT command, there may be no echo. If you then input the command at and press Enter, and it returns "OK," it indicates that everything is working properly. If you need to check the echo, please type the command: ate1, then press Enter. After that, you can continue to type other commands and see the inputs.
Common AT commands:
1. Check if the SIM card is detected:
at+cpin?
Return ready to indicate the card has been recognized, if return error, you need to check the hardware.
2. Check antenna signal quality:
at+csq
Return values between 26 and 31 indicate a good signal, with 31 representing a full signal strength; return values between 20 and 25 indicate a barely acceptable signal; return values below 20 indicate a poor signal or that the antenna might not be connected.
3. Check network registration status:
at+cops?
Normally, it should return the network supporter's code: 7, where 7 represents 4G.
Note: The above command at+csq should not include a question mark, while the other two commands require a question mark.
4. View the SIM card's IMEI code:
at+cgsn
5. Reset 4G module (Sometimes, if you reinsert the SIM card, hot swapping may not work; in such cases, you can use this reset command to reset the module.):
at+reset
6. Disable radio frequency:
at+cfun=0
Enable radio frequency:
at+cfun=1
The two commands mentioned above can be used in pairs to allow the module to re-register with the network without restarting the 4G module.
3.4 Enable SIM card hot-swapping
This expansion board supports SIM card hot-swapping, but this feature is disabled by default. To enable it, first remove the SIM card, and then open the AT command serial port:
sudo minicom -D /dev/ttyACM0
Execute:
at+csdt=1
If the output is "OK," it indicates that the setting was successful.
You can use AT+CSDT? to check the current status. A return value of 1 indicates that the SIM card hot-swapping feature has been enabled.
Insert the SIM card without powering off, execute the following commands separately. If all commands are successful (with eth0 being the 4G module), it confirms that hot-swapping is supported:
sudo udhcpc -i eth0
ping www.mcuzone.com -I eth0
3.5 Notes
For the USB version, if connected to a Raspberry Pi Zero series board, it generally requires an expansion board with USB ports. Additionally, whether it is the USB version or the Probe version, the 4G module operates as a USB Host device. Therefore, it is necessary to enable USB Host mode in the OS's config.txt file. Otherwise, USB devices may not function, and the OS might even get stuck at the Raspberry Pi logo during boot:
The processing method is as follows:
For the hardware, please observe carefully whether the thimble is aligned with the gold-plated contact. For the OS, please open the config.txt file in the root directory of the TF card system partition on the PC end to check the USB initialization script:
Please confirm whether the three red boxed areas in the image below are fully configured. If not, manually add the missing configurations and save the file:
# otg_mode=1(It is recommended to comment this out)
dtoverlay=dwc2,dr_mode=host(Ensure to include at both required locations)
IV. 4G Application (Remote Control)
RPi-Connect provides a service for secure access to your Raspberry Pi from anywhere. With this service, combined with the Zero Cat1 4G Probe version, you can still remotely access your Raspberry Pi even when outdoors without a Wi-Fi network. Note: To use this service, Bookworm or a newer OS must be running. Additionally, only the Raspberry Pi 5, 4, or 400 can use screen sharing. The Zero 2W can only use Remote Shell. The following demonstrates how to configure the remote connection service.
4.1 Automatically obtain DNS server
The 4G CAT1 module is driver-free and can automatically establish a 4G connection upon each startup. However, for the Raspberry Pi OS version 2023-12-05-bookworm and later versions, udhcpc is required to obtain the correct DNS server.
After using udhcpc to obtain the DNS server, if the OS is restarted, it is necessary to execute udhcpc again to get the DNS server. If automatic DNS server acquisition is required after reboot, proceed as follows:
Open rc-local service:
sudo sudo systemctl enable --now rc-local
Use the following command to open rc.local:
sudo nano /etc/rc.local
Add the command you want to execute at startup above the line exit 0, and then save the file (in this example, eth0 represents the 4G module, but the name should match the actual interface identified on your OS):
sleep 5 && sudo udhcpc -i eth0 && sleep 5 && sudo udhcpc -i eth0 && sleep 5 && sudo udhcpc -i eth0
The sleep command is used to delay the execution of subsequent commands by a certain number of seconds. Since the 4G module needs some time to acquire an IP address, to prevent `udhcpc` from failing, it needs to be executed several times with a delay added between each execution. As a result, the 4G network becomes usable approximately 20 seconds after the OS boots up.
4.2 Apply for a Raspberry Pi ID
If you already have a Raspberry Pi ID, please log in directly. If not, please follow the steps below to apply.
Open the website at https://id.raspberrypi.com/, and enter the email address and password you wish to use:
After creating the account, you need to verify it by entering your email:
After verification is complete, the ID can be used.
4.3 Install Remote Service
Open the SSH terminal and install the Raspberry Pi Connect software. If the installation command indicates that it is already installed, then no additional installation is necessary:
sudo apt install rpi-connect
After installation, we enter loginctl enable-linger in the terminal to ensure that the remote service is automatically enabled each time the OS restarts:
Restart the OS. In the graphical interface, select the items in the order shown in the following image to ensure that Raspberry Pi Connect is turned on:
Then enter the following in the Raspberry Pi terminal:
rpi-connect signin
Now, a URL is displayed, as shown in the image above. Open this URL in a browser (it is recommended to use another computer, as the Zero series can be very slow when opening a browser due to hardware limitations).
Click on "Sign in" and follow the prompts to bind the device. First, you need to set the device name:
Click "Create device and sign in":
This completes the binding process, and there will also be a successful message displayed in the terminal:
4.4 Use remote control
On your PC, open: https://connect.raspberrypi.com/devices
The Zero 2W device just added only shows "Remote shell", indicating that this device can only be controlled through a remote command-line interface.
Click on "Connect" to open the remote command-line interface, where you can then enter commands:
After configuration is complete, the OS will be able to connect to the internet via 4G each time it boots up and will also enable the Raspberry Pi Connect remote service. This way, we can control the device through a remote command-line interface from a PC.
V. Power consumption explanation
| RPi0-CAT1 4G | Status | Power consumption |
| 5V power supply | Module standby | 0.15A*5V=0.75W |
| Speed test (downlink) | 0.25A*5V=1.25W | |
| Speed test (uplink) | 0.3A*5V=1.5W |
VI. Expansion board selection guide
Contact Us
QQ：8204136
Email: mcuzone@vip.qq.com
Tel: +86(0)13957118045
If there are any omissions, errors, or infringements on this page, please contact us through the above methods. Thank you!
Copyright 2004-2025 Wildchip