CM4-WRT-A

This repository contains the source code for the software and firmware necessary to utilize the custom features of the CM4-WRT-A: A Raspberry Pi CM4 Router Baseboard with NVME support. Currently sold on Tindie: https://www.tindie.com/products/mytechcatalog/rpi-cm4-router-baseboard-with-nvme/

The repository is organized as follows:

Directory	Description
CM4	Source code for picod: A service for communicating with the Raspberry Pi Pico
pico	Firmware for the Raspberry Pi Pico microcontroller
case	STL files for a 3D printed case for the CM4-WRT-A

Documentation

• Overview of the CM4-WRT-A
• How to install OpenWRT on the CM4-WRT-A router
• How to monitor the CM4-WRT-A board temperatures and fan speed (RPM) in InfluxDB

Install Prerequisites

The build scripts for the CM4-WRT-A rely on Docker. If you would like to build OpenWrt or the Raspberry Pi Pico firmware for the CM4-WRT-A, install Docker with these commands on the terminal in Ubuntu or Debian: See https://docs.docker.com/desktop/install/linux-install/ for further details.

sudo apt update
sudo apt install -y docker.io
sudo usermod -aG docker $USER

Building OpenWrt (with picod included)

It will be possible to update this OpenWrt build by adding kmods and packages from the official repository using opkg, or LuCI software interface.

1. Clone this repository:

   git clone https://github.com/MyTechCatalog/cm4-wrt-a.git

2. Run the OpenWrt build script:

   cd cm4-wrt-a && ./build-openwrt.sh

3. The OpenWrt images will be located in this folder: cm4-wrt-a/bin/targets/bcm27xx/bcm2711/

4. Upon first boot up, install the following kmods: kmod-i2c-core kmod-i2c-bcm2835 kmod-nvme

   root@OpenWrt:~# opkg update
   root@OpenWrt:~# opkg install kmod-i2c-core kmod-i2c-bcm2835 kmod-nvme
   

The build script will use the latest tag/version from the OpenWrt repo. If you need to build a specific OpenWrt release version in step 2 above, specify the tag name after the script, for example: ./build-openwrt.sh v23.05.6

Verifying that picod is running on OpenWrt

After running the following command: ubus call picod status, you should see output similar to:

root@OpenWrt:~# ubus call picod status
{
    "fan_pwm_pct": {
        "System_Fan_J17": 50,
        "CM4_FAN_J18": 50
    },
    "watchdog": {
        "is_enabled": "false",
        "timeout_sec": 10,
        "max_retries": 0
    },
    "temperature_c": {
        "PCIe_Switch": "36.2",
        "M.2_Socket_M_J5": "34.5",
        "M.2_Socket_E_J3": "34.8",
        "M.2_Socket_M_J2": "33.0",
        "RPi_Pico": "37.4",
        "Under_CM4_SOC": "36"
    },
    "tachometer_rpm": {
        "System_Fan_J17": 3420,
        "CM4_FAN_J18": 0
    }
}

Otherwise, if you get an error such as the one below:

root@OpenWrt:~# ubus call picod status
Command failed: Not found

It means that the name of the CM4's serial port (device path) connected to the RPi Pico, is different from the default value in the picod configuration file /etc/picod.conf.

Edit line 29 in the config file /etc/picod.conf by replacing /dev/ttyAMA3 with the second device path obtained from the output of the following command:

root@OpenWrt:~# ls /dev/ttyA*
/dev/ttyAMA0  /dev/ttyAMA1

For example, based on the above output, line 29 of /etc/picod.conf should be edited to read:

pico_serial_device_path="/dev/ttyAMA1"

Start the picod service, and then verify that it is running as described above:

root@OpenWrt:~# /etc/init.d/picod start

Building the picod service for Raspbian or Debian variants

Cross-compiling with Docker

Assuming you have Docker installed as described in the prerequisites above, run the commands below:

cd CM4
make docker-cross
./build-picod.sh

The debian package picod_1.0_arm64.deb will be located in CM4/build folder. Copy it to the Raspberry Pi and install it with this command:

dpkg -i picod_1.0_arm64.deb

Starting the picod service (on Raspbian)

sudo systemctl daemon-reload
sudo systemctl enable picod.service
sudo systemctl start picod.service

You can then access the picod web interface at http://localhost:8086/. This location is not accessible from outside the RPi CM4 itself. As such, an SSH tunnel can be created with the following command to forward port 8086 to localhost on your computer:

ssh -L 8086:localhost:8086 username@cm4_ip_address

Update config.txt

Copy to CM4/config_rpios.txt to /boot/firmware/config.txt in order to configure/enable the custom interfaces on the board.

Compiling the Raspberry Pi Pico firmware

1. Clone this repository if you haven't already done so from above:

   git clone https://github.com/MyTechCatalog/cm4-wrt-a.git

2. Run the Pico build script:

   cd cm4-wrt-a && ./build-pico-firmware.sh

3. The firmware will be located here : cm4-wrt-a/pico/build/cm4-wrt-a.uf2

Contact information

Email: cm4-wrt-a@mytechcatalog.com