Pulse Out

A general-purpose per-pulse GPIO output. One module covers piezo, small speaker via a transistor, LED and attenuated line-out into a powered speaker. Single edge or resonant burst, configurable polarity, all non-blocking.

This is the lightweight cousin of the Audio Tick output: no I2S, no amplifier IC, no synthesis. A real mechanical tick per pulse, available on every ESP build.

Included in every shipped ESP build. Disabled by default; set the pin and enable it from Config > Pulse Out after flashing.

Settings

Setting	Key	Type	Default	Description
Enable	`pulse.enable`	Boolean	`0` off	Takes effect on save, no reboot needed.
GPIO	`pulse.pin`	Int -1 to max GPIO	`-1`	GPIO driving the load. `-1` keeps the pin idle.
Polarity	`pulse.polarity`	`0` Active high, `1` Active low	`0` Active high	Active high suits most cases. Active low is for common-anode LEDs and inverted MOSFET drivers.
Mode	`pulse.mode`	`0` Pulse, `1` Burst, `2` LED fade	`0` Pulse	Single pulse, resonant burst (for a piezo or speaker) or LED fade.
Pulse width ms	`pulse.pulse_ms`	Int 1-50	`5`	Single-pulse width in milliseconds. 1 ms for audio, several ms for LEDs.
Burst Hz	`pulse.freq`	Int 1000-8000	`3500`	Burst frequency in Hz. For a piezo, match its marked resonance.
Burst cycles	`pulse.cycles`	Int 1-10	`1`	Cycles per burst. More = louder + slightly longer.
Fade rate	`pulse.fade_shift`	`0` Fast, `1` Medium, `2` Slow	`1` Medium	Fade decay rate: Fast is ~100 ms, Medium ~250 ms, Slow ~500 ms.
Brightness	`pulse.brightness`	Int 0-100	`100`	LED brightness in percent (LED loads only). Applies to Pulse and Fade modes.
Max Hz	`pulse.max_hz`	Int 0-200	`20`	Cap on clicks per second. `0` removes the cap.
Quiet from	`pulse.quiet_from`	Time HH:MM	(empty)	Silence clicks from this time. Blank = off.
Quiet to	`pulse.quiet_to`	Time HH:MM	(empty)	End of the quiet window; crosses midnight if from > to.

Output is rate-limited to max_hz clicks per second, 20 by default. At high CPS the audio thins out while the counter still tracks every pulse.

Driving another counter

Pulse Out is an indicator, not a count relay. At the default max_hz of 20 a downstream counter stops seeing new pulses above 1200 CPM and reads a flat line, not an error.

To relay counts instead, set max_hz to 0 and pulse_ms to 1. The output then follows every count up to roughly 500 per second (30,000 CPM), above which a new count arriving mid-pulse is dropped.

Two things to know before relying on it:

Per-device voice variation jitters pulse_ms by a few percent (see below). Harmless for a counter reading edges, wrong if the receiver measures width.
Quiet hours silence the output. A relay set up inside a quiet window looks like a dead tube at the far end.

Per-device voice variation

Each device picks a small offset on pulse_ms and freq based on its chip ID, so two units next to each other sound subtly different rather than identical.

Use as an LED blink or fade

Same module, different load. Wire an LED (with current-limit resistor) to the chosen GPIO and pick a mode:

mode=0, pulse_ms=5 to 20: visible hard flash per click.
mode=2 (LED fade): full brightness on each click, then exponential decay via PWM. Looks like a Geiger-counter afterglow. fade_shift controls the decay rate (0 ~100 ms, 1 ~250 ms, 2 ~500 ms).
polarity=0 if the LED’s anode is on the GPIO side, polarity=1 if the cathode is on the GPIO side (common-anode wiring).

Note: fade mode is LED only. Feeding PWM into a piezo or speaker would produce a soft sustained tone, not a click.

Fade mode overlaps the built-in Blip LED. Both ship; pick whichever fits your wiring. Blip LED lives on the board’s dedicated pin, Pulse Out on any GPIO you choose.

Patterns

Audio jack into a powered speaker

Use when you already have a desk speaker or aux input. Attenuate 3.3 V down to roughly line level and AC-couple.

GPIO ---[R1: 10 kohm]---+---[C1: 1 uF]---o tip
                        |
                      [R2: 4.7 kohm]
                        |
                       GND --------------o sleeve

Part	Why
R1 + R2	Voltage divider: 3.3 V x 4.7 / (10 + 4.7) ~= 1.05 V, consumer line level.
C1	Blocks the divider’s DC bias so the line-in only sees the click transient. Non-polar 1 uF.

Recommended settings: mode=0, pulse_ms=1. The powered speaker’s amp shapes the click.

Piezo disc or passive buzzer module

GPIO ----+---- Piezo lead 1
              Piezo lead 2 ---- GND

No extra parts. Volume tier depends on the piezo:

Bare ceramic disc: wristwatch tick.
Passive buzzer module (disc in a plastic Helmholtz cavity): distinct tick across a small room.

Active buzzers (the “5 V buzzer module” kind with an internal oscillator) will not work in click mode. They can only buzz while powered. Look for “passive” piezos.

Recommended settings:

Quietest, sharpest: mode=0, pulse_ms=1.
Loudest at 3.3 V: mode=1, cycles=3, freq= whatever’s marked on the piezo (typical: 2700, 3500, 4000 Hz).

Small speaker via MOSFET

Use when you want room-filling clicks. The MOSFET sources current from a 5 V rail so the speaker isn’t limited to what a GPIO can sink.

GPIO ---[220 ohm]--- Gate (2N7000)
                     |
                     Drain --- Speaker(-)
                               Speaker(+) --- +5 V
                                              ^
                     Drain ---[1N4148]--------+
                                  (cathode/band toward +5V)
                     Source --- GND

Part	Purpose
2N7000 (or BS170)	Logic-level N-channel MOSFET; switches cleanly from a 3.3 V GPIO. TO-92.
220 ohm	Gate-current limiter.
1N4148	Flyback diode across the speaker. Absorbs the inductive kick when the pulse turns off.
4-8 ohm speaker	The driver.

BJT alternative: BC337 NPN with a 1 kohm base resistor. The 2N3904 also works but is quieter. Keep the flyback diode either way.

Recommended settings: mode=1, cycles=2, freq=2500. Tune freq to taste; lower sounds woodier, higher sounds tinnier.

Ideas

Glowing LED: mode=2 fades the LED after each click. Try fade_shift=2 for a longer afterglow; drive a 1 W LED through a MOSFET for a desk lamp that reacts across a room.
Click and flash together: with Audio Tick running, add Pulse Out on a spare GPIO with mode=0, pulse_ms=20.
Headphones: mode=0, pulse_ms=1 into the attenuator pattern above (10 kohm + 4.7 kohm + 1 uF) gives a tick you can listen to on headphones.

Comparison with Audio Tick

	Pulse Out	Audio Tick
Platforms	ESP8266 + ESP32	ESP32 only
Hardware	Piezo, small speaker (via MOSFET), or line-out into a powered speaker	I2S amplifier IC + speaker
Sound	Mechanical tick	Synthesised click with chirp + decay
Boot chime	None	7 chimes + random

Run both at once if you like. They share the same 20 clicks/sec cap.