am8 — fifine AM8 control for Linux

Command-line control of the fifine AmpliGame AM8 USB microphone (3142:a010, MVsilicon chip) on Linux: mute, digital gain, noise gate and a mic EQ, applied automatically on plug-in.

It talks to the microphone's vendor HID interface (interface 4) with MVsilicon's ACP protocol, the same channel the vendor's tuning tools use. No kernel driver is needed. Protocol details and research notes are in PROTOCOL.md.

The RGB lighting cannot be controlled over USB on this firmware. See PROTOCOL.md.

Requirements

• Python 3 with pyusb (apt install python3-usb or pip install pyusb)
• libusb 1.0

Usage

am8-cli.py status
am8-cli.py mute on|off|toggle
am8-cli.py gain DB                    digital mic gain, -90..+12 dB (stock +6)
am8-cli.py noise off|low|mid|high     noise gate (low = stock: -45 dB, ratio 3)
am8-cli.py noise THRESHOLD_DB RATIO   custom gate, e.g. noise -35 4
am8-cli.py lowcut off|on [HZ]         high-pass filter, default 100 Hz
am8-cli.py clarity off|DB             presence boost at 3 kHz, 0..+9 dB
am8-cli.py bass off|DB                low shelf at 150 Hz, -12..+9 dB
am8-cli.py monitor PERCENT            headphone volume (the hardware knob overrides it)
am8-cli.py apply [FILE]               run every line of FILE (default ~/.config/am8.conf)

Add --dry to any command to print the USB frames without sending them. Every write is verified by reading the value back (ok / NOT applied).

Example:

$ python3 am8-cli.py status
mute    : off
gain    : +6.00 dB
noise   : on  (threshold -45.0 dB, ratio 3, attack 5, release 500)
monitor : 100%
lowcut  : on, 150 Hz
clarity : +4.0 dB at 3000 Hz
bass    : +3.0 dB at 150 Hz

Notes

• Settings live in the microphone's RAM and are lost when it is unplugged. Use apply and the systemd unit below to restore them on every plug-in.
• The mic gain knob is analog and invisible to the firmware; gain acts on top of it.
• Software mute does not update the mute button's internal state or its LED. After a software mute, the button needs two presses (red, then green) to unmute.

Installation

cp am8-cli.py ~/.local/bin/am8-cli; chmod +x ~/.local/bin/am8-cli

# access without sudo, and a hook that applies defaults on plug-in
sudo cp 70-fifine-am8.rules /etc/udev/rules.d/
sudo udevadm control --reload && sudo udevadm trigger --attr-match=idVendor=3142

# defaults
cp am8.conf ~/.config/am8.conf

# apply defaults on every plug-in
mkdir -p ~/.config/systemd/user
cp am8-defaults.service ~/.config/systemd/user/
systemctl --user daemon-reload

The unit runs ~/.local/bin/am8-cli; edit ExecStart if the script lives elsewhere. Check it with journalctl --user -u am8-defaults.

am8.conf holds one am8-cli.py command per line:

lowcut on 150
bass 3
clarity 4
noise low

The udev rule must sort before 73-seat-late.rules (which turns the uaccess tag into an ACL), hence the 70- prefix. It also sets group plugdev.

Safety

The ACP channel also carries commands that can brick the chip. am8-cli.py refuses to send them:

CTRL	Why
0x11	writes SPI-flash sectors
0xFE	OTA trigger on stock MVsilicon firmware (reboots into the flash bootloader)
0xFB, 0xFD, 0xFF	out-of-bounds handling / encryption lock
0xA0, 0xA1, 0xA3	voice changer / auto-tune; enabling them overloads the mic and makes it re-enumerate

Never write the 8-byte Feature report: SET_REPORT(Feature) with 0x55/0xAA arms the upgrade flag, and the next GET_REPORT(Feature) jumps into the bootloader.

If anything goes wrong, unplug and replug the microphone; all settings return to stock.