Get Started Using cfnet-fs

On the ModularPi, add the following to /boot/firmware/config.txt and reboot:

[pi5]
pciex1=on
dtoverlay=uart0-pi5
dtoverlay=uart4-pi5
dtoverlay=i2c0-pi5,pins_8_9,baudrate=100000
dtoverlay=i2c1-pi5,pins_2_3,baudrate=1000000
dtoverlay=i2c3-pi5,pins_22_23,baudrate=1000000

NOTE: I²C port 0 can also be configured for 1MHz, if you are only using CFADC-A4L and CFDAC-2V modules on that port.

sudo apt update
sudo apt install libfuse3-4 fuse3

Download cfnet-fs now.

Or, download directly to your target device using a terminal program like wget or curl.

wget https://downloads.comfiletech.com/CFNET/cfnet-fs/release/1.0.0/linux-arm64/cfnet-fs
chmod +x cfnet-fs

Once downloaded, run the executable as illustrated below to create the virtual file system.

cfnet-fs {mount-point} {i2c1-device} {i2c2-device} {i2c3-device}

For the ModularPi, use

cfnet-fs /tmp/cfnet-fs /dev/i2c-0 /dev/i2c-1 /dev/i2c-3

• mount-point can be any directory the user running the program has access to.
• /dev/i2c-0 is the I²C port for analog modules
• /dev/i2c-1 is the I²C port digital input modules
• /dev/i2c-3 is the I²C port digital output modules

While cfnet-fs is running, use ordinary file system utilities like ls or tree to navigate the file system at the mount point (e.g. /tmp/cfnet-fs).

$ tree /tmp/cfnet-fs/
├── analog-input
│   └── 0
│       └── channel
│           ├── 0
│           │   ├── amps.txt
│           │   ├── amps.bin
│           │   ├── volts.txt
│           │   └── volts.bin
│           ├── 1
│           │   ├── amps.txt
│           │   ├── amps.bin
│           │   ├── volts.txt
│           │   └── volts.bin
│           ...
├── analog-input
│   └── 1
│       └── channel
│           ├── 0
│           │   ├── amps.txt
│           │   ├── amps.bin
│           │   ├── volts.txt
│           │   └── volts.bin
│           ...
├── analog-output
│   └── 0
│       └── channel
│           ├── 0
│           │   ├── raw.txt
│           │   └── volts.txt
│           └── 1
│               ├── raw.txt
│               └── volts.txt
├── analog-output
│   └── 1
│       └── channel
│           ├── 0
│           │   ├── raw.txt
│           │   └── volts.txt
│           ...
├── digital-input
│   └── 0
│       ├── channel
│       │   ├── 0
│       │   │   ├── state.txt
│       │   │   └── state.bin
│       │   ├── 1
│       │   │   ├── state.txt
│       │   │   └── state.bin
│       │   ...
│       ├── state.txt
│       └── state.bin
├── digital-input
│   └── 1
│       ├── channel
│       │   ├── 0
│       │   │   ├── state.txt
│       │   │   └── state.bin
│       ...
└── digital-output
    ├── 0
    │   ├── channel
    │   │   ├── 0
    │   │   │   ├── state.txt
    │   │   │   └── state.bin
    │   │   ├── 1
    │   │   │   ├── state.txt
    │   │   │   └── state.bin
    │   │   ...
    │   ├── state.txt
    │   └── state.bin
    └── 1
        ├── channel
        │   ├── 0
        │   │   ├── state.txt
        │   │   └── state.bin
        ...

Automate the modules by simply reading from and writing to the files in the mount point.

echo 1 > /tmp/cfnet-fs/digital-output/0/channel/3/state.txt

File.WriteAllText("/tmp/cfnet-fs/digital-output/0/channel/3/state.txt", "1");

with open("/tmp/cfnet-fs/digital-output/0/channel/3/state.txt", "w") as f:
    f.write("1")

FILE *f = fopen("/tmp/cfnet-fs/digital-output/0/channel/3/state.txt", "w");
fputs("1", f);
fclose(f);