proart-meter

Linux daemon that drives the front-panel LED temperature meter on ASUS ProArt LC 420 AIO liquid coolers. It reads the CPU temperature from the kernel hwmon subsystem and maps it to the cooler's 5-bar LED display over USB HID.

ASUS ships a Windows-only utility (ProArt Creator Hub) for this. There is no official Linux support. This project was built by reverse-engineering the USB protocol from packet captures of the Windows software.

Hardware

Field	Value
Device	ASUS ProArt LC 420
USB Vendor ID	0x0B05 (ASUSTeK)
USB Product ID	0x1AFE
USB Interface	2 (HID)
Interrupt Endpoint	0x82 (IN)

The cooler exposes multiple USB interfaces. Interface 2 is the HID interface used to control the LED meter. The kernel's built-in HID driver must be detached before userspace can claim it (handled automatically via libusb_set_auto_detach_kernel_driver).

USB Protocol

All communication uses HID SET_REPORT (Output) via USB control transfers, with an interrupt IN endpoint for device responses.

Transport Layer

Every outbound message is a 65-byte HID Output report sent as a control transfer:

Parameter	Value	Description
bmRequestType	0x21	Host-to-device, Class, Interface
bRequest	0x09	SET_REPORT
wValue	0x02EC	Report Type=Output (0x02), Report ID=0xEC
wIndex	0x0002	Interface 2
wLength	65	Report ID byte + 64 bytes payload

The first byte of the buffer is always the report ID (0xEC). The remaining 64 bytes carry the command payload, zero-padded.

Device responses are read from interrupt endpoint 0x82 as 65-byte transfers.

Command Reference

Direct Write (0x40)

Sets bar colors and active level on the meter display.

Byte 0: 0x40  (command)
Byte 1: 0x80  (subcommand)
Byte 2: 0x00  (reserved)
Byte 3: level (0x00-0x05, number of bars to illuminate)
Byte 4+: RGB color data, 3 bytes per bar, 5 bars = 15 bytes

Color data is 5 triplets of [R, G, B], one per bar from bottom to top.

Reset (0xB8)

Resets the meter controller state. Sent before every level change. The device responds with a status packet on the interrupt endpoint which must be read (and can be discarded).

Byte 0: 0xB8

Mode Set (0x35)

Configures the meter operating mode.

Byte 0: 0x35
Byte 1: 0x00
Byte 2: 0x00
Byte 3: 0x00
Byte 4: 0xFF

Initialization Sequence

On startup, the following sequence is sent (replayed from Windows capture):

1. 4x Direct Write (0x40 0x80 0x00 0x02 <colors>) -- pre-load bars with color data
2. Reset (0xB8)
3. Read interrupt endpoint (discard response)
4. Mode Set (0x35 0x00 0x00 0x00 0xFF)

Level Update Sequence

To change the meter level (0-5 bars illuminated):

1. Reset (0xB8)
2. Read interrupt endpoint (discard response)
3. Mode Set (0x35 0x00 0x00 0x00 0xFF)
4. 5x Direct Write (0x40 0x80 0x00 <level> <colors>) with 20ms delay between each

The level byte controls how many bars are lit. The 5 repeated writes with inter-packet delay are required -- the device does not reliably update with fewer.

Temperature Mapping

The daemon reads CPU temperature from /sys/class/hwmon/*/temp1_input (matched by sensor name) and maps it to a meter level using 5 configurable thresholds:

temp < thresholds[0]           -> level 0 (all bars off)
temp >= thresholds[0]          -> level 1
temp >= thresholds[1]          -> level 2
temp >= thresholds[2]          -> level 3
temp >= thresholds[3]          -> level 4
temp >= thresholds[4]          -> level 5 (all bars on)

The meter only updates on level changes, not every poll cycle.

Configuration

/etc/proart-meter/config.yaml:

sensor: "k10temp"
poll_interval_seconds: 2
thresholds: [40, 50, 60, 70, 80]

Field	Type	Description
sensor	string	hwmon sensor name (e.g. k10temp for AMD, coretemp for Intel)
poll_interval_seconds	int	Seconds between temperature reads
thresholds	int[5]	Temperature thresholds in Celsius, ascending order, exactly 5 values

Find your sensor name:

cat /sys/class/hwmon/hwmon*/name

Dependencies

• libusb -- USB device communication
• lm_sensors -- kernel modules for hardware temperature monitoring

Building from Source

git clone https://github.com/cagriekin/proart-meter.git
cd proart-meter
make build
sudo make install

Arch Linux (AUR)

yay -S proart-meter-git

Or build the package manually:

git clone https://github.com/cagriekin/proart-meter.git
cd proart-meter
makepkg -si

Usage

# Start the service
sudo systemctl enable --now proart-meter

# Check status
sudo systemctl status proart-meter

# View logs
journalctl -u proart-meter -f

The daemon requires root or appropriate USB permissions to access the device. On shutdown (SIGINT/SIGTERM), it resets the meter to level 0 before exiting.

License

MIT