Digital inputs & outputs

The prebuilt HCP PCBs (v2 and v3.x) have four extra screw terminals: In1, In2, Out1 and Out2. They are disabled by default and enabled per channel under I/O Configuration.

HCP miniThe HCP mini uses the same HCP_Giffordv3 firmware but has no In/Out terminals – leave the channels disabled there.

Electrical limits – read first

Inputs In1 / In2

Type	≈5 V voltage input through a fixed divider (1.2 kΩ series, 2.2 kΩ to GND) – not a dry contact
HIGH	≈ 3.9 … 5.1 V at the terminal against board GND
Idle	LOW – the on-board 2.2 kΩ pulls the input down
Maximum	≈ 5.1 V. Never apply 12 V or 24 V – that destroys the GPIO.
Pull mode	Keep none (external) – the internal pull-up cannot work against the on-board 2.2 kΩ.
Debounce	50 ms

A push button must therefore switch about 5 V onto the terminal; a potential-free contact across the terminals does nothing. A 3.3 V signal is not detected reliably.

Outputs Out1 / Out2

Type	High-side switch – optocoupler-driven N-channel MOSFET (source follower)
ON	Sources the rail selected by the `5V \| – \| 3V` jumper, minus about one MOSFET threshold (≈ 0.7–1.5 V)
OFF	High impedance (floating)
Suitable for	PLC inputs, active-HIGH relay module inputs, logic inputs
Not suitable for	Driving relays, lamps, motors or mains loads directly
Isolation	None – both sides of the optocoupler share the board GND

Prefer the 5 V jumper position: with 3 V selected the output only reaches about 2.3 V.

Pins

Terminal	HCP PCB v2	HCP PCB v3.x	Other boards
In1	GPIO12	GPIO12	any free GPIO
In2	GPIO14	GPIO14	any free GPIO
Out1	GPIO37	GPIO25	any free GPIO
Out2	GPIO35	GPIO22	any free GPIO

The firmware rejects unusable pins and disables the channel, reporting it as io_error in the debug topic: 0 (not configured), the SPI flash pins (ESP32: 6–11, ESP32-S3: 26–32) and, as outputs, the input-only GPIO34–39 of the classic ESP32.

Settings

Setting	Inputs	Outputs
Enable	Activates the channel and its Home Assistant entity.
Name	Entity name in Home Assistant.
GPIO	Pin number (see above).
Pull resistor	none (external) on the HCP PCBs; pull-up/-down only on self-built boards without divider	–
Active low	Only for a button to GND with pull-up on self-built boards	Only if ON/OFF end up swapped
Local action	Action executed by the bridge itself on the activating edge – works without Wi-Fi/MQTT	–
Restore after reboot	–	Off (default) = always off after a restart; on = last state is restored

Local actions

Value	Action
0	none – only publish the input state
1	impulse / toggle door (open if not fully open, otherwise close)
2 / 3 / 4	open / close / stop door
5	toggle the operator light
6 / 7	ventilation / half-open position
8 / 9	toggle Out1 / Out2

Examples

Wall button toggles the light

+5V ────o/ o──── In1     (button, bridge GND shared)

I/O Configuration → Input 1: enable, GPIO 12, pull none (external), active low off, local action toggle light. The button now switches the light directly on the bus, and the press is also available as binary_sensor in Home Assistant.

Out1 drives a relay module

Relay module IN → Out1, module GND → bridge GND, module VCC → its own 5 V supply, jumper on 5 V. The module must be active HIGH; common active-LOW boards need an extra inverting stage. Output 1: enable, GPIO 25 (v3), active low off, restore off.

MQTT and HTTP

# state (retained, only enabled channels)
hormann/<id>/io                {"in1":"true","in2":"false","out1":"false","out2":"true"}

# switch outputs: true | false | anything else toggles
hormann/<id>/command/out1      true
hormann/<id>/command/out2      toggle

# HTTP: on | off | toggle   (404 if the output is not enabled)
curl "http://<device-ip>/io?output=1&state=on"

Inputs become binary_sensor, outputs switch entities in Home Assistant.

Wiring diagrams, the complete electrical analysis and ESPHome snippets: inputs_outputs.md.