Epomaker TIDE 75 — Community Firmware

Community-maintained QMK firmware for the Epomaker TIDE 75 mechanical keyboard (tri-mode: USB / Bluetooth / 2.4GHz wireless).

This firmware fixes three critical bugs in the stock Epomaker firmware. All fixes have been submitted as pull requests to the official repository, but remain unmerged as of March 2026. This repo provides a pre-compiled binary so you can flash the fixes immediately without setting up a build environment.

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Quick Start

1. Download epomaker_tide75_default.bin from the latest release
2. Enter bootloader mode — hold Escape while plugging in USB
3. Flash using QMK Toolbox — select the .bin file, click Flash
4. Done — unplug and reconnect. All three fixes are now active.

Note: Holding Escape while connecting will also reset your keyboard settings (RGB mode, etc.) to defaults. If you want to preserve settings, use the Fn+RShift+Esc method instead (see Flashing below).

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Bug Fixes

1. USB Wake from Sleep

Upstream PR: Epomaker/tide75#4

Symptom: Keyboard becomes completely unresponsive after the host computer wakes from sleep/hibernate while connected via USB. Requires unplugging and reconnecting.

Root cause: suspend_power_down() is called when the host suspends, but suspend_wakeup_init() is never called on resume, leaving the keyboard in a suspended state.

Fix: Track the USB suspend state and properly call suspend_wakeup_init() when the host resumes.

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2. Debounce / Double Keypress

Upstream PR: Epomaker/tide75#5

Symptom: Intermittent double key registrations — pressing a key once occasionally types the character twice.

Root cause: The stock firmware has no explicit debounce configuration, defaulting to an inadequate value for mechanical switches. Additionally, force_nkro is enabled, which can cause compatibility issues with certain hosts and KVM switches.

Fix: Set explicit debounce of 8ms (matching QMK recommended defaults) and disabled force_nkro.

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3. Wireless Modifier + First-Character Drops

Upstream PR: Epomaker/tide75#6

Symptom: After the keyboard wakes from idle sleep in wireless mode (2.4GHz or Bluetooth), modifier keys are dropped and the first character typed is lost. For example:

• Cmd+Shift+4 registers as $ (Shift+4, with Cmd lost) instead of triggering macOS screenshot
• Cmd+C does nothing (Cmd lost, just types 'c')
• Typing "hello" after idle produces "ello" (first character lost)

Root cause: Two independent issues compound:

1. Modifier destruction: The low-power wakeup callback (lpwr_wakeup_cb) calls suspend_wakeup_init() which invokes clear_mods() approximately 200ms after the MCU wakes. By that point, the main loop has already scanned the wake-up keys and registered their modifiers. clear_mods() destroys that state, and because held keys aren't re-processed by the matrix debouncer (it sees them as already pressed), the modifiers are never re-registered.

2. Cold radio link: The 2.4GHz radio link is cold after sleep. The first HID report is sent before the radio re-establishes, so it is lost over the air.

Fix (multi-layered, developed over 15 iterations of debugging):

• Override lpwr_wakeup_cb() to skip the destructive clear_mods() call — the keyboard only sleeps after 1 minute of idle (no keys held), so there is no stale state to clear
• Prime the radio module on wakeup via wireless_devs_change() to begin re-establishing the link immediately
• Post-sleep resync: re-deliver keyboard state at 15ms intervals for 1200ms after wake, ensuring the first keypress is delivered once the radio warms up (~60-80ms)
• Skip NKRO overflow messages during resync to prevent a modifier race condition between 6KRO and NKRO radio packets
• Periodic keepalive (1000ms) to prevent the radio link and dongle USB from entering power-saving modes
• Dedup cache invalidation API added to QMK core for resync support

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Flashing

Enter Bootloader Mode

Method	How	Notes
Reset switch	Hold the Reset switch on the bottom of the PCB while connecting USB	Requires physical access to PCB
Escape key	Hold Escape while connecting USB	Resets keyboard settings to defaults
Key combo	Press Fn + Right Shift + Escape	Works with default keymap, preserves settings

Flash the Binary

Option A — QMK Toolbox (recommended for most users)

1. Download and install QMK Toolbox
2. Open QMK Toolbox, select epomaker_tide75_default.bin
3. Put the keyboard in bootloader mode
4. Click Flash

Option B — Command line

wb32-dfu-updater_cli -t -s 0x08000000 epomaker_tide75_default.bin

Verify the Binary

Property	Value
File	epomaker_tide75_default.bin
Size	61,152 bytes
SHA256	a663a89c0ba7df5d15286d9b089900ccbec1009827b4a94e55735a13ccd83ea4

shasum -a 256 epomaker_tide75_default.bin
# Should output: a663a89c0ba7df5d15286d9b089900ccbec1009827b4a94e55735a13ccd83ea4

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Building from Source

For advanced users who want to modify or rebuild the firmware.

Prerequisites

• QMK CLI installed and configured
• ARM GCC toolchain (arm-none-eabi-gcc)

Build Steps

1. Clone the Epomaker QMK fork:

   git clone https://github.com/hangshengkeji/qmk_firmware.git
   cd qmk_firmware
   git checkout tri-mode
   git submodule update --init --recursive

2. Overlay the patched source files:

   # Keyboard source (into keyboards/epomaker/tide75/)
   cp -r /path/to/tide75-firmware/src/tide75/* keyboards/epomaker/tide75/
   
   # QMK core patches
   cp src/quantum/action_util.c quantum/action_util.c
   cp src/quantum/action_util.h quantum/action_util.h

3. Compile:

   qmk compile -kb epomaker/tide75 -km default

4. The output binary will be at .build/epomaker_tide75_default.bin

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Hardware Info

Property	Value
Keyboard	Epomaker TIDE 75
Connectivity	USB / Bluetooth / 2.4GHz wireless
Processor	WB32FQ95 (ARM Cortex-M3)
Bootloader	wb32-dfu
Firmware base	QMK (Epomaker fork)
Matrix	6 rows x 15 columns
RGB	WS2812 (per-key RGB matrix)
Encoder	1 rotary encoder

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Upstream Status

All fixes have been submitted to the official Epomaker repository. As of March 2026, none have been merged:

PR	Fix	Status
#4	USB wake from sleep	Open
#5	Debounce / double keypress	Open
#6	Wireless modifier + first-character drops	Open

If and when these PRs are merged upstream, this repository may be archived.

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License

This project is licensed under the GNU General Public License v2.0, consistent with the upstream QMK firmware and Epomaker source code.

Credits

• Epomaker — Original TIDE 75 firmware and hardware
• QMK Firmware — Open-source keyboard firmware framework
• @jkquickstar — Bug investigation, fixes, and community firmware