miku's firmwares

Advanced

Nothing here is validated except the default. Recovery is still the express key combo, but you will be doing it blind.

Drive periods per excitation routine, of 29 stock

Below 8 drive periods is unexplored. 8 is 28% of the pen's stock energy and 4 is 14%. Nobody has been down there, and at some point the tablet simply stops finding the pen. Watch pressure max in the measurement script: if it stops reaching 8191 the drive is no longer enough and you have found the floor.

Worth knowing before you try: the still rate is already at the 1000 Hz USB ceiling, so it cannot go up. The moving rate is held down by an 11 sample rescan that fires when the signal drops, and weaker drive makes that fire more often. Cutting further may well make the number that matters worse.

Settle delays, microseconds ADC median Take one ADC sample per measurement instead of three

Untested. Nobody has flashed this. Each measurement currently converts three times and takes the median, which rejects outliers. Taking one saves about 128µs of every report, and because that is a fixed saving it is worth more the faster you already are. On a tablet near 950 Hz it models past the 1000 Hz USB ceiling, so it is the cheapest route to the cap. What it costs is outlier rejection, which Smooth may already be covering.

ADC sample time

Untested. Every measurement converts three times, so shortening the aperture is worth three times the saving on each. Unlike dropping to one sample, which breaks tracking outright, this degrades gradually: too short and the sample capacitor does not fully charge, which shows up as noise and scale error rather than a cursor in the corner. Work down one step at a time and stop when lines get worse.

Coarse scan window Widen from 5 coils to 7

Untested, and it is 17 sites rather than one. A still pen reports around 100 Hz faster than a moving one, because moving pushes the signal peak to the edge of the search window where the firmware cannot interpolate, so it falls back to an 11 sample rescan. A wider window costs 2 measurements on every report and saves 11 each time it avoids that. If it goes wrong the cursor will not track properly, which is obvious immediately. Reflash without it to undo.

Pen click and express keys Disable pen click and express keys

Untested. Nobody has flashed this yet. Turns off the tip click, the pen's side buttons and the four express keys, by marking those fields as padding in the report descriptors so Windows ignores them. Hover and pressure are untouched, and OpenTabletDriver reads a different interface, so it keeps full pen data and whatever you have bound there. Added for a report of phantom Escape presses at the faster presets. Windows caches these descriptors, so unplug and replug after flashing, and remove the device in Device Manager if it does not take. Reflash without it to undo, and the express key combo still enters DFU because the bootloader reads those keys before the firmware runs.

Rescan sensitivity

Untested. When the pen's signal drops below this fraction of the previous report, the firmware runs an 11 sample rescan to find it again, and that is what makes a moving pen report slower than a still one. At reduced drive the signal is small enough that noise trips it constantly. A smaller fraction means it fires less. Too small and the tablet will be slow to pick the pen up after a real lift, which shows as a pause rather than anything broken.

Smoothing floor

Untested. Only does anything with Smooth selected. The filter smooths harder the slower the pen moves, and stops at 40 of 256. That is its limit, and it is reached when the pen is sitting still. Lowering the floor smooths a stationary pen harder without touching how it behaves when you move, because the upper limit is unchanged. The cost is latency while nearly still, which is where you cannot feel it.

Each site costs its value times how often it fires, so coil recovery is about four times cheaper to restore than the other two. A drive period costs roughly 27µs. No site may be 0: stock_wait_us loads SysTick with microseconds times 72, so a 0 reload never raises COUNTFLAG and the wait never returns.