Arduino Port Expander¶
With this sketch you can control pins of a remote Arduino board through ESPHome. The Arduino acts as a port expander, allowing you to use more pins than a standard ESP8266/ESP32 has.
The Arduino is connected to the ESP via I²C. Most Arduinos use the A4 and A5 pins for the I²C bus
so those pins are not available to read from ESPHome.
It is recommended to use a 3.3V I/O level Arduino, however using 5V Arduinos seems to work too. In the latter
case you should power your 5V Arduino with 3.3V otherwise you will need a level converter for the
I²C bus.
Currently it is supported:
reading digital inputs
reading analog inputs
writing digital outputs
The Arduino sketch can be retrieved from here
you can rename it to .ino and use the Arduino IDE to program it.
You need to download arduino_port_expander.h and include the arduino_port_expander.h in the ESPHome configuration.
esphome:
# ...
includes:
- arduino_port_expander.h
Setup your I²C Bus and assign it an id:
i2c:
id: i2c_component
By default ESP8266 uses SDA pin GPIO4 which you need to connect to Arduino’s A4 and the SCL
is GPIO5 which goes to Arduino’s A5.
Then create a custom_component, this will be the main component we will be referencing later when creating
individual IOs.
custom_component:
- id: ape
lambda: |-
auto ape_component = new ArduinoPortExpander(i2c_component, 0x08);
return {ape_component};
By default the I²C address is 0x08 but you can change it on the Arduino sketch so you can have more devices
on the same bus.
Now it is time to add the ports.
Binary_Sensor¶
When adding binary sensors the pins are configured as INPUT_PULLUP, you can use any PIN from 0 to 13 or
A0 to A3 (A4 and A5 are used for I²C and A6 and A7 do not support internal pull up)
Note
Arduino PIN 13 usually has a LED connected to it and using it as digital input with the built in internal pull up might be problematic, using it as an output is preferred.
To setup binary sensors, create a custom platform as below, list in braces all the sensors you want, in the example below two binary sensors are declared on pin 9 and A0 (number 14)
Then declare the ESPHome reference of the binary sensor in the same order as declared in the lambda:
binary_sensor:
- platform: custom
lambda: |-
return {ape_binary_sensor(ape, 9),
ape_binary_sensor(ape, 14) // 14 = A0
};
binary_sensors:
- id: binary_sensor_pin2
name: Binary sensor pin 2
- id: binary_sensor_pin3
name: Binary sensor pin 3
on_press:
...
The listed binary_sensors supports all options from Binary Sensor like
automations and filters.
Sensor¶
Sensors allows for reading the analog value of an analog pin, those are from A0 to A7 except for
A4 and A5. The value returned goes from 0 to 1023 (the value returned by the Arduino analogRead
function).
Arduino analog inputs measures voltage. By default the sketch is configured to use the Arduino internal VREF comparer setup to 1 volt, so voltages bigger are read as 1023. You can configure Arduino to compare the voltage to VIN voltage, this voltage might be 5 volts or 3.3 volts, depending on how you are powering it. To do so, pass an additional true value to the hub constructor:
auto ape_component = new ArduinoPortExpander(i2c_component, 0x08, true);
To setup sensors, create a custom platform as below, list in braces all the sensors you want,
in the example below two sensors are declared on pin A1 and A2
Then declare the ESPHome reference of the sensor in the same order as declared in the lambda:
sensor:
- platform: custom
lambda: |-
return {ape_analog_input(ape, 1), // 1 = A1
ape_analog_input(ape, 2)};
sensors:
- name: Analog A1
id: analog_a1
filters:
- throttle: 1s
- name: Analog A2
id: analog_a2
filters:
- throttle: 2s
The listed sensors supports all options from Sensor like
automations and filters.
Note
Sensors are polled by default every loop cycle so it is recommended to use the throttle filter
to not flood the network.
Output¶
Arduinos binary outputs are supported in pins from 0 to 13.
To setup outputs, create a custom platform as below, list in braces all the outputs you want,
in the example below two outputs are declared on pin 3 and 4
output:
- platform: custom
type: binary
lambda: |-
return {ape_binary_output(ape, 3),
ape_binary_output(ape, 4)};
outputs:
- id: output_pin_3
inverted: true
- id: output_pin_4
inverted: true
switch:
- platform: output
name: Switch pin 3
output: output_pin_3
light:
- platform: binary
name: Switch pin 4
output: output_pin_4
Full Example¶
Let’s connect a 4 channel relay board and 2 push buttons to toggle the relays, a PIR sensor, a window and a door a LM35 temperature sensor and a voltage sensor. Seems a bit too much for an ESP8266? You’ll still have some spares I/Os.
esphome:
name: test_arduino
includes:
- arduino_port_expander.h
esp8266:
board: nodemcu
wifi:
ssid: !secret wifi_ssid
password: !secret wifi_password
api:
ota:
platform: esphome
# define i2c device
# for an ESP8266 SDA is D2 and goes to Arduino's A4
# SCL is D1 and goes to Arduino's A5
i2c:
id: i2c_component
logger:
level: DEBUG
# define the port expander hub, here we define one with id 'expander1',
# but you can define many
custom_component:
- id: expander1
lambda: |-
auto expander = new ArduinoPortExpander(i2c_component, 0x08, true);
return {expander};
# define binary outputs, here we have 4, as the relays are inverse logic
# (a path to ground turns the relay ON), we defined the inverted: true
# option of ESPHome outputs.
output:
- platform: custom
type: binary
lambda: |-
return {ape_binary_output(expander1, 2),
ape_binary_output(expander1, 3),
ape_binary_output(expander1, 4),
ape_binary_output(expander1, 5)};
outputs:
- id: relay_1
inverted: true
- id: relay_2
inverted: true
- id: relay_3
inverted: true
- id: relay_4
inverted: true
# connect lights to the first 2 relays
light:
- platform: binary
id: ceiling_light
name: Ceiling light
output: relay_1
- platform: binary
id: room_light
name: Living room light
output: relay_2
# connect a fan to the third relay
fan:
- platform: binary
id: ceiling_fan
output: relay_3
name: Ceiling fan
# connect a pump to the 4th relay
switch:
- platform: output
name: Tank pump
id: tank_pump
output: relay_4
# define binary sensors, use the Arduino PIN number for digital pins and
# for analog use 14 for A0, 15 for A1 and so on...
binary_sensor:
- platform: custom
lambda: |-
return {ape_binary_sensor(expander1, 7),
ape_binary_sensor(expander1, 8),
ape_binary_sensor(expander1, 9),
ape_binary_sensor(expander1, 10),
ape_binary_sensor(expander1, 14) // 14 = A0
};
binary_sensors:
- id: push_button1
internal: true # don't show on HA
on_press:
- light.toggle: ceiling_light
- id: push_button2
internal: true # don't show on HA
on_press:
- light.toggle: room_light
- id: pir_sensor
name: Living PIR
device_class: motion
- id: window_reed_switch
name: Living Window
device_class: window
- id: garage_door
name: Garage garage
device_class: garage_door
# define analog sensors
sensor:
- platform: custom
lambda: |-
return {ape_analog_input(expander1, 1), // 1 = A1
ape_analog_input(expander1, 2)};
sensors:
- name: LM35 Living room temperature
id: lm35_temp
filters:
# update every 60s
- throttle: 60s
# LM35 outputs 0.01v per ºC, and 1023 means 3.3 volts
- lambda: return x * 330.0 / 1023.0;
- name: Analog A2
id: analog_a2
filters:
- throttle: 2s