Overview
The gpio-out node controls digital output pins on Raspberry Pi and compatible
single-board computers. Use it to turn LEDs on/off, switch relays, control motors through driver boards, and
any other digital output control.
Important Safety Notice
Never connect GPIO pins directly to loads drawing more than 16mA. Use transistors, MOSFETs, or relay modules for motors, solenoids, and other high-current devices. Exceeding current limits can permanently damage your Pi.
Common Use Cases
LED Control
Drive status LEDs and indicator lights
Relay Switching
Control high-power devices via relay modules
Motor Direction
Control H-bridge motor drivers for direction
Buzzer/Alarm
Trigger audible alerts and notifications
Properties
| Property | Type | Required | Default | Description |
|---|---|---|---|---|
| pin | number | Yes | - | GPIO pin number (BCM numbering) |
| initialValue | boolean | No | false | Initial output state on deploy |
| invert | boolean | No | false | Invert output logic (HIGH=0 for active-low devices) |
| persistState | boolean | No | false | Persist pin state across restarts |
| stateFile | string | No | /var/lib/edgeflow/gpio_states.json | File path for persisted state |
| failsafeMode | boolean | No | false | Enable failsafe — set pin to a safe state on error or cleanup |
| failsafeValue | boolean | No | false | Value to set when failsafe triggers (false = LOW) |
| driveStrength | number | No | - | Drive strength in mA (for supported pins) |
Inputs
Controls the output state of the GPIO pin. Accepts multiple field names and formats.
value: true → Set HIGH value: false → Set LOW state / on / payload → Also accepted as field names numeric > 0 → Treated as true (HIGH) Outputs
Passes through the input message with updated state.
{
"payload": {
"pin": 17,
"value": true // actual written value (after invert)
}
}Wiring Examples
LED with Resistor
GPIO 18 → 330Ω Resistor → LED (+) → LED (-) → GND
Current = (3.3V - 2V) / 330Ω ≈ 4mA (safe)
Standard indicator LED circuit
Relay Module (Active-Low)
GPIO 23 → IN (Relay)
5V → VCC (Relay)
GND → GND (Relay)
Set invert: true for active-low relays
Example Flows
Blink LED Every Second
Use inject node's toggle mode to alternate true/false automatically — no Function node needed.
[
{
"id": "blink-inject",
"type": "inject",
"name": "Toggle 1s",
"intervalType": "seconds",
"intervalValue": 1,
"repeat": true,
"toggle": true,
"payload": { "value": true }
},
{
"id": "led-out",
"type": "gpio-out",
"name": "LED Pin 17",
"pin": 17
}
]toggle option makes payload.value alternate between true and false on each tick.
Motion-Activated Light
Turn on light when motion detected, auto-off after 30 seconds.
Failsafe & State Persistence
Failsafe Mode
When enabled, the pin is set to a known safe state on errors or when EdgeFlow shuts down. Critical for controlling heaters, pumps, or other devices that should default to OFF.
failsafeMode: true — enable failsafe
failsafeValue: false — set LOW on error/shutdown
State Persistence
Enable persistState to save pin state to disk.
After a restart, the pin will be restored to its last known state.
Default state file: /var/lib/edgeflow/gpio_states.json
Customize with the stateFile property
Troubleshooting
LED not turning on
- Check LED polarity (long leg is positive/anode)
- Verify resistor value is not too high
- Test with multimeter: should read ~3.3V when HIGH
- Try a different GPIO pin
Relay clicking but not switching load
- Check if using NO (Normally Open) vs NC (Normally Closed) terminals
- Verify relay module is powered with 5V (not 3.3V)
- Ensure load wiring is secure in screw terminals
Output stays LOW/HIGH permanently
- Check if another process is controlling the same pin
- Redeploy flows to reset pin state
- Verify pin is not reserved for system use (I2C, SPI, UART)