Internal GPIO handling

The ESP module can control things with it’s build-in GPIO output pins. We can turn these on or off or we can set these pins to a special pulse modulated value (PWM output). And it’s also possible to send short pulses (single pulse) to one of these pins to control specific devices that are switched with a single short high or low signal.

Plugin details

Type: GPIO handling

Name: Internal

Status: NORMAL

GitHub: P001_Switch.ino

Maintainer: Core

Used libraries: .

Commands available

Internal GPIO handling NORMAL

Supported hardware: Relay, Servo motor

Command (GPIO/Value)

Extra information


GPIO: 0 … 16


2 (HIGH-Z, input)

1 (HIGH, output)

0 (LOW, output)

Basic on/off.. We can control a pin with simple http URL commands. To change the pin to high or low steady output. Setting GPIO to 2 means that it will be able to detect low level relays (with high impedance, Z).


GPIO: 0 … 16

Toggle on/off.. Toggle the current (output) state of the given GPIO pin. This will only be executed on pins set to be in output mode.


GPIO: 0 … 16

State: 1/0

Duration: 1 … 999 S

To send a *long* pulse to a certain pin.. A long pulse is basically the same as the plain pulse. Duration is defined in seconds, which makes it more suitable for longer duration. This command is not blocking, but will send 2 events to start and stop the pulse. This may have some variation depending on the system load of the module. Variation is typically up-to 10 msec, but may be up-to a second, depending on active plugins and controllers performing blocking operations.


GPIO: 0 … 16

State: 1/0

Duration: 10 … 15000 msec

To send a *long* pulse to a certain pin. A LongPulse_mS is the same as the regular LongPulse. The only difference is the time base in milliseconds rather than in seconds.


GPIO: 0 … 16

State: 1/0

Duration: 0 … 1000 msec

To send a *short* pulse to a certain pin. Example to send an active high (1) pulse on GPIO 14 for 500 mSeconds. Pulse duration is in milliseconds. State is 1 or 0. N.B. this is a blocking call, meaning no other actions will be performed during the pulse.




GPIO: 0 … 15

Duty: 0 … 1023

Duration: 100 … 15000 msec (optional)

Frequency: 100 … 40000 Hz (optional)

To set a certain PWM level. If you have set a certain GPIO to a PWM level and want to use it as a regular HIGH/LOW pin you need to reset by setting the PWM level to 0.

Duration (in msec) parameter will create a fading. Value of 0 will not set a duration.

Frequency (in Hz) will be set to 1000 Hz when not given. Frequencies above 30 kHz are not stable and will likely crash the ESP.


GPIO: 0 … 15

Servo: 1/2

Position: -180 … 180 (see warning below)

To control a servo motor. We currently support a maximum of two servo motors so you can build a pan & tilt device if you like.


Most servos are not able to turn full 360°! Normally the servos are able to go from -90° to 90°, some rare servos do allow for -135° to 135°.

A position value of 9000 will stop the PWM signal. This can be useful to save energy on servos which do not need power to remain at the same position.


GPIO: 0 … 16

To monitor a GPIO state. By the use of the command you will receive events when the GPIO state of that pin is changed from 1 to 0 and from 0 to 1.


GPIO: 0 … 16

To toggle a GPIO state. With this command you can change the given state of a pin from either 1 to 0 or from 0 to 1.

Internal GPIO handling NORMAL

Supported hardware: Buzzer (RTTTL), Piezo element, Speaker (Ringtones etc.)

Command (GPIO/Value)

Extra information


GPIO: 12 … 16

Tone: 20 … 13000 Hz

Duration: 100 … 15000 msec

You should try to use GPIO 12…16 since these generally aren’t used. The recommended tone range is 20 Hz … 13 kHz. Up-to 40 kHz should be possible to generate, but will be inaudible for humans. Frequencies above 30 kHz are not stable and will likely crash the ESP.

Duration is set in ms.

N.B. tones with a duration less than 50 msec will be blocking. Longer duration will use the scheduler, which may cause some fluctuations in the duration.


GPIO: 12 … 16

Value: d=<duration>,o=<octave>,b=<tempo>,<notes…>

You should try to use GPIO 12…16 since these generally aren’t used by ESP internal functions. N.B. Playing a tune is blocking for as long as the tune is playing.

Value can be defined like <name_of_melody:duration,octave,beat,notes….>

For example: rtttl,14,test:d=8,o=5,b=180,c6,b,c6,p,g,g-

More RTTTL Ringtone Downloads

Change log

Changed in version 2.0:

added Major overhaul for 2.0 release.

New in version 1.0:

added Initial release version.