Aura HID Protocol Reference

This document describes the HID protocol used by the 2025 ASUS ROG Flow Z13 for RGB lighting control. It is intended for developers who want to understand or reimplement this functionality.

The protocol was reverse-engineered from g-helper (MIT license), specifically app/USB/AsusHid.cs (device I/O) and app/USB/Aura.cs (packet construction).

Devices

The 2025 ROG Flow Z13 exposes two separate HID devices for lighting:

Device	USB Product ID	Role	Controls
Keyboard	`0b05:1a30`	`keyboard`	Key backlight
Lightbar	`0b05:18c6`	`lightbar`	Edge light strip

Both devices use the same Aura protocol and accept the same packet format. Commands are sent independently to each device; there is no broadcast shortcut that addresses both at once. Each device responds only to the zone byte that matches its own zone (keyboard = zone 0, lightbar = zone 1) and silently ignores commands for the other zone.

The hidraw Interface

Linux exposes raw HID devices at /dev/hidraw0, /dev/hidraw1, etc. Writing to these files sends an output report directly to the device, bypassing any input subsystem drivers.

Access: The files require read/write permission. By default this means root. A udev rule can grant a specific group access without requiring privilege escalation for each command:

SUBSYSTEM=="hidraw", ATTRS{idVendor}=="0b05", ATTRS{idProduct}=="18c6", \
    GROUP="users", MODE="0660"
SUBSYSTEM=="hidraw", ATTRS{idVendor}=="0b05", ATTRS{idProduct}=="1a30", \
    GROUP="users", MODE="0660"

Write size: The Aura protocol uses 64-byte output reports. Every write must be exactly 64 bytes. Shorter packets must be zero-padded to fill the buffer before writing.

Report ID: The first byte of every write is the HID report ID. For Aura, this is always 0x5d. The hidraw interface includes the report ID in the write buffer (unlike some HID APIs that strip it). This means byte 0 of every packet you write is 0x5d, and the actual command byte is at offset 1.

Discovering Devices

The kernel creates sysfs entries for every hidraw device under /sys/class/hidraw/. Each device has an associated uevent file that contains the HID_ID, which encodes the bus type, vendor, and product IDs in a fixed format.

Path pattern: /sys/class/hidraw/hidraw*/device/uevent

HID_ID format: HID_ID=BUSTYPE:VENDORID:PRODUCTID (all hex, zero-padded to 8 digits)

Example for the lightbar:

HID_ID=0003:00000B05:000018C6

Bus 0003 = USB HID
Vendor 00000B05 = ASUS (0x0b05)
Product 000018C6 = N-KEY device (lightbar, 0x18c6)

To convert a sysfs uevent path to the corresponding /dev/hidrawN path, extract the hidrawN component from position 4 of the path split by /:

/sys/class/hidraw/hidraw3/device/uevent  ->  /dev/hidraw3

Confirming Aura Support

Not every hidraw node with a matching USB ID actually supports the Aura report. Multiple HID interfaces are present on each USB device, and only one of them carries Report ID 0x5d. You can confirm support by reading the HID report descriptor via ioctl and scanning for the two-byte sequence [0x85, 0x5d]:

0x85 is the HID short-form item tag for "Report ID"
0x5d is the Aura report ID value

// Get descriptor size
int size;
ioctl(fd, HIDIOCGRDESCSIZE, &size);  // ioctl 0x80044801

// Read descriptor
struct {
    uint32_t size;
    uint8_t  value[4096];
} desc;
desc.size = size;
ioctl(fd, HIDIOCGRDESC, &desc);      // ioctl 0x90044802

// Scan for Report ID 0x5d
for (int i = 0; i < size - 1; i++) {
    if (desc.value[i] == 0x85 && desc.value[i+1] == 0x5d) {
        // This device supports Aura report 0x5d
    }
}

ioctl numbers (Linux, 64-bit):

HIDIOCGRDESCSIZE = 0x80044801
HIDIOCGRDESC = 0x90044802

Packet Format

All Aura packets follow this structure:

Offset  Len  Field
------  ---  -----
0       1    Report ID (always 0x5d)
1       1    Command byte
2+      N    Command-specific payload
(end)   ...  Zero padding to reach 64 bytes total

The full 64-byte buffer is always written to the hidraw device, regardless of how many payload bytes the command actually uses. Any unused bytes must be set to zero.

Protocol Flow

A complete lighting update requires this sequence of packets:

Init()           -- 4 packets: wake device, identify, configure, activate lightbar
SetPower(on)     -- 1 packet:  enable power to all lighting zones
SetBrightness()  -- 1 packet:  set brightness level (0-3)
SetMode(zone 0)  -- 1 packet:  set color/mode for keyboard
Commit()         -- 2 packets: latch the zone 0 change
SetMode(zone 1)  -- 1 packet:  set color/mode for lightbar
Commit()         -- 2 packets: latch the zone 1 change

Total: 11 packets per full update. Init and SetPower/SetBrightness are sent once per session. SetMode and Commit must be sent once for each zone you want to update.

Commands

Init

Sent once before any other command to wake the device and activate the lightbar. All four packets must be sent in order.

Packet 1 — Wake

Offset  Byte  Meaning
------  ----  -------
0       5d    Report ID
1       b9    Init command
2-63    00    Zero padding

Packet 2 — ASUS Identification String

Offset  Bytes                            Meaning
------  -----                            -------
0-14    5d 41 53 55 53 20 54 65          ASCII: ]ASUS Tech.Inc.
        63 68 2e 49 6e 63 2e
15-63   00                               Zero padding

The string ]ASUS Tech.Inc. is sent as raw ASCII. The first character ] has ASCII value 0x5d, which is also the report ID — so the first byte of this packet doubles as both the ] character and the report ID. Do not prepend an additional 0x5d byte.

Packet 3 — Mode Config Header

Offset  Byte  Meaning
------  ----  -------
0       5d    Report ID
1       05    Command
2       20    Config byte
3       31    Config byte
4       00    Config byte
5       1a    Config byte
6-63    00    Zero padding

Packet 4 — Z13 Dynamic Lighting Init

Offset  Byte  Meaning
------  ----  -------
0       5d    Report ID
1       c0    Command
2       03    Subcommand
3       01    Enable flag
4-63    00    Zero padding

This packet is required for the 2025 ROG Flow Z13 lightbar. Without it, the lightbar will not respond to SetMode commands. It is safe to send to the keyboard device as well; it is simply ignored there.

SetPower

Enables or disables power to all lighting zones simultaneously.

Offset  Byte  Meaning
------  ----  -------
0       5d    Report ID
1       bd    Command
2       01    Subcommand
3       keyb  Keyboard power flags
4       bar   Lightbar power flags
5       lid   Lid power flags
6       rear  Rear power flags
7       ff    Terminator (always 0xff)
8-63    00    Zero padding

Power-on values:

Field	Value	Notes
keyb	`ff`	All power states enabled
bar	`1f`	Bits 0-4 set: Awake, Boot, Awake(dup), Sleep, Shutdown
lid	`ff`	All power states enabled
rear	`ff`	All power states enabled

Power-off values: all four fields set to 00. The terminator byte ff at offset 7 is present regardless of power state.

The bar byte uses a bitmask to select which power states the lightbar is active in:

Bit	Power state
0	Awake
1	Boot
2	Awake (duplicate)
3	Sleep
4	Shutdown

0x1f (binary 00011111) enables all five states.

SetBrightness

Sets the keyboard backlight brightness level.

Offset  Byte   Meaning
------  ----   -------
0       5d     Report ID
1       ba     Command
2       c5     Config byte
3       c4     Config byte
4       level  Brightness level (0x00-0x03)
5-63    00     Zero padding

Level values:

Level	Byte	Meaning
Off	`00`	Backlight disabled
Low	`01`	Minimum brightness
Medium	`02`	Mid brightness
High	`03`	Maximum brightness

Values above 0x03 should be clamped to 0x03 before sending.

SetMode

Sets the color and animation mode for a single zone. Must always be followed by a Commit sequence.

Offset  Byte      Meaning
------  ----      -------
0       5d        Report ID
1       b3        Command
2       zone      Zone number (00 = keyboard, 01 = lightbar)
3       mode      Animation mode
4       r         Primary color, red channel (0x00-0xff)
5       g         Primary color, green channel
6       b         Primary color, blue channel
7       speed     Animation speed
8       dir       Direction (0x00 = default)
9       randFlag  Color selection flag
10      r2        Secondary color, red channel (breathe mode only)
11      g2        Secondary color, green channel
12      b2        Secondary color, blue channel
13-63   00        Zero padding

Mode values:

Name	Byte	Description
`static`	`00`	Solid color, no animation
`breathe`	`01`	Pulse between two colors
`cycle`	`02`	Cycle through spectrum
`rainbow`	`03`	Rainbow wave
(star)	`04`	Random pixels blink — not supported on Z13 2025
(rain)	`05`	Dripping color — not supported on Z13 2025
`strobe`	`0a`	Rapid flash
(comet)	`0b`	Trailing comet — not supported on Z13 2025
(flash)	`0c`	Flash burst — not supported on Z13 2025

Speed values:

Name	Byte
Slow	`e1`
Normal	`eb`
Fast	`f5`

randFlag values and when to use them:

Value	Meaning	When to use
`00`	Use primary color (r, g, b)	Any mode with a non-zero color
`01`	Dual-color mode	`breathe` with a non-zero primary color
`ff`	Device selects color	When r, g, and b are all zero

The logic for choosing randFlag:

if r == 0 and g == 0 and b == 0:
    randFlag = 0xff   # all-zero color signals "random"
elif mode == breathe:
    randFlag = 0x01   # enables use of the r2/g2/b2 secondary color
else:
    randFlag = 0x00   # use r/g/b directly

For modes other than breathe, the r2/g2/b2 fields are unused and should be set to zero.

Commit

Two packets that must be sent after every SetMode to latch the pending state. Without them, the mode change is accepted by the device but not applied to the lighting output.

MESSAGE_SET (send first):

Offset  Byte  Meaning
------  ----  -------
0       5d    Report ID
1       b5    MESSAGE_SET command
2-63    00    Zero padding

MESSAGE_APPLY (send second):

Offset  Byte  Meaning
------  ----  -------
0       5d    Report ID
1       b4    MESSAGE_APPLY command
2-63    00    Zero padding

Always send MESSAGE_SET (b5) before MESSAGE_APPLY (b4). The order matters.

Zones

The Z13 has two lighting zones that must be addressed separately:

Zone	Byte	USB Product	Physical location
Keyboard	`00`	`0b05:1a30`	Key backlight
Lightbar	`01`	`0b05:18c6`	Edge light strip

Each physical USB device responds only to its own zone byte. If you send a SetMode with zone 00 (keyboard) to the lightbar hidraw node, the packet is silently ignored. The same applies in reverse.

In practice, you can send all packets to both devices and let each device filter by zone — this matches how g-helper operates. Alternatively, look up each device separately and send each zone's packets only to the matching device.

Annotated Packet Examples

Static red on both zones, full brightness

The complete packet sequence for setting both the keyboard and lightbar to solid red at maximum brightness:

// Init packet 1: wake device
5d b9 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

// Init packet 2: ASUS identification string "]ASUS Tech.Inc."
5d 41 53 55 53 20 54 65 63 68 2e 49 6e 63 2e 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

// Init packet 3: mode config header
5d 05 20 31 00 1a 00 00 00 00 00 00 00 00 00 00
00 ... (zero-padded to 64 bytes)

// Init packet 4: Z13 dynamic lighting (required for lightbar)
5d c0 03 01 00 00 00 00 00 00 00 00 00 00 00 00
00 ... (zero-padded to 64 bytes)

// SetPower: all zones on
// [id] [cmd] [sub] [keyb] [bar] [lid] [rear] [term]
5d     bd     01    ff     1f    ff    ff     ff    00 ...

// SetBrightness: level 3 (high)
// [id] [cmd] [c5] [c4] [level]
5d     ba     c5   c4   03     00 ...

// SetMode: zone 0 (keyboard), static, red (#FF0000), normal speed
// [id] [cmd] [zone] [mode] [r ] [g ] [b ] [spd] [dir] [flag] [r2] [g2] [b2]
5d     b3     00     00     ff   00   00   eb    00    00     00   00   00  00 ...

// MESSAGE_SET (latch zone 0)
5d b5 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ... (64 bytes)

// MESSAGE_APPLY (apply zone 0)
5d b4 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ... (64 bytes)

// SetMode: zone 1 (lightbar), static, red (#FF0000), normal speed
// [id] [cmd] [zone] [mode] [r ] [g ] [b ] [spd] [dir] [flag] [r2] [g2] [b2]
5d     b3     01     00     ff   00   00   eb    00    00     00   00   00  00 ...

// MESSAGE_SET (latch zone 1)
5d b5 00 00 ... (64 bytes)

// MESSAGE_APPLY (apply zone 1)
5d b4 00 00 ... (64 bytes)

Breathe between cyan and blue, slow speed

// SetMode: zone 0, breathe, cyan (#00FFFF) primary, blue (#0000FF) secondary
// [id] [cmd] [zone] [mode] [r ] [g ] [b ] [spd] [dir] [flag] [r2] [g2] [b2]
5d     b3     00     01     00   ff   ff   e1    00    01     00   00   ff  00 ...
//                   ^breathe    ^---cyan---  ^slow       ^dual    ^---blue---

// randFlag = 0x01 because mode is breathe and primary color is non-zero.
// The device animates between the two colors.

Cycle mode with device-chosen colors

// SetMode: zone 0, cycle, black primary (device picks color), normal speed
// [id] [cmd] [zone] [mode] [r ] [g ] [b ] [spd] [dir] [flag] [r2] [g2] [b2]
5d     b3     00     02     00   00   00   eb    00    ff     00   00   00  00 ...
//                   ^cycle      ^all zero   ^normal   ^random

// randFlag = 0xff because r, g, and b are all 0x00.
// The device cycles through its own color sequence.