GPIO Pins

Most of the pins on the ESP32 can be used for inputs and outputs. Exceptions are labelled above and described below.

Breadboard

Breadboards and dupont wires provides an easy way to connect components to your device.

When connecting your ESP32 to a breadboard, it is recommended to plug in only one side to each breadboard. Like this...

If you need to use the other side as well, use a second breadboard...

Digital Output (Write)

Writing a 1 to a pin will set it to HIGH (3.3V). Writing a 0 to a pin will set it to LOW (0V).

Wiring Example

If you do not have a suitable LED, you can use Pin 2 instead. Pin 2 is connected to an internal Blue LED.

Code

This example code turns the LED on/off every 1 second.

Blocks

Python

import time
from ioty import pin

while True:
    pin.digital_write(15, 1)
    time.sleep(1)
    pin.digital_write(15, 0)
    time.sleep(1)

Digital Input (Read)

Reading a pin will return 1 when it is HIGH (3.3V), and a 0 when it is LOW (0V).

It is often useful to enable the internal pull-up resistor when using a pin as an input; this will ensure that the pin is HIGH when it is not connected to anything, and LOW when connected to GND. Without a pull-up resistor, the pin will be indetermined when not connected, and may give you random values.

Wiring Example

If you do not have a suitable push button, you can used Pin 0 instead. Pin 0 is connected to the BOOT button on the ESP32.

Code

This example code turns the built-in LED (Pin 2) on when the button (...connected to Pin 4) is pressed, and off when it is released.

Blocks

To add the else to an if block, use the gear icon. You can use the same method to add an else if if you require it.

Python

from ioty import pin

pin.set_pin_mode(4, pin.PULL_UP)
while True:
    if pin.digital_read(4) == 0:
        pin.digital_write(2, 1)
    else:
        pin.digital_write(2, 0)

Touch Input

Some of the pins on the ESP32 are capable of detecting capacitive touch. This allows you to use these pins as buttons, by simply connecting a wire to the pin and touching the wire.

The values returned by the "touch read pin" block will tend to be high (...100s to over 1000) when there is no contact, and low (...less than 100) when there is contact. The exact value will vary, and you'll need to test to determine it.

Wiring Example

Note that the wire is not connected to anything; we'll be using the wire itself to detect touch. To make a better touch button, you can connect the wire to an uninsulated paper clip or a piece of metal foil.

Code (touch test)

We'll start with a simple code that displays the touch values. This will let us know what values to expect when there is contact and no contact.

Blocks (touch test)

Python (touch test)

import time
from ioty import pin

while True:
    print(pin.touch_read(4))
    time.sleep(1)

Results (touch test)

Check the monitor for the results. Touch the wire and see how the values change.

In this case, the values are around 500+ when there is no contact, and around 60-140 when there is contact.

Code (touch button)

Based on our test results, we can pick a number between the contact and no-contact values. In this case, 300 would be roughly in the middle between the two ranges, but be warned that you may get a different value from me.

If the touch read value is below 300, we'll consider it to be touched, and turn on the Blue LED. Else, we'll turn the LED off. This is similar to the digital input exercise where we used a button, but here we are using a wire as a button.

Blocks (touch button)

Python (touch button)

import time
from ioty import pin

while True:
    if pin.touch_read(4) < 300:
        pin.digital_write(2, 1)
    else:
        pin.digital_write(2, 0)