EZO-PRS — ESPHome Component for the Atlas Scientific Pressure Sensor

An ESPHome external component that turns an Atlas Scientific EZO-PRS embedded pressure sensor into a first-class, I²C-connected sensor for ESP32 and Home Assistant.

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Overview

The Atlas Scientific EZO-PRS is a high-precision embedded pressure sensor that speaks the Atlas Scientific EZO command protocol over I²C. This repository provides a complete, native ESPHome component (ezo_prs) so you can read and control the sensor declaratively from YAML — no custom firmware required.

With this component you can:

• 📈 Read pressure in your choice of unit — psi, atm, bar, kPa, inH₂O or cmH₂O
• 🔢 Configure precision from 0 to 3 decimal places
• 🛠️ Calibrate the zero and high points, and clear calibration
• ⚖️ Manage offsets (set / read / clear)
• 💡 Control the on-board LED
• ℹ️ Read device information and status into Home Assistant text sensors
• ⌨️ Send any raw EZO command for full low-level control

📄 Full hardware specifications, command set and wiring are in the included EZO-PRS Datasheet (PDF).

Supported hardware

Item	Detail
Sensor	Atlas Scientific EZO-PRS embedded pressure sensor
Bus	I²C (default address 0x6A)
MCU	ESP32 (esp32dev and compatible boards)
Framework	ESPHome

Hardware setup

Wire the EZO-PRS to your ESP32 over I²C:

EZO-PRS	ESP32
VCC	3.3 V
GND	GND
SDA	any I²C-capable GPIO (SDA)
SCL	any I²C-capable GPIO (SCL)

The I²C pins are configurable. The bundled example.yaml uses SDA = GPIO15 and SCL = GPIO16; the common ESP32 defaults are SDA = GPIO21 / SCL = GPIO22. Pick whatever your board exposes and set them in the i2c: block.

Installation

Method 1 — External component (recommended)

Point ESPHome at this repository and it will pull the component automatically:

external_components:
  - source: github://jnrivra/EZO_PRS@main
    components: [ezo_prs]

Method 2 — Reusable package

Include the ready-made package, which adds the external component and a configured pressure sensor in one line (your config must define an I²C bus with id: bus_a):

packages:
  ezo_prs: github://jnrivra/EZO_PRS/ezo_prs.yaml@main

Method 3 — Manual installation

Copy the component into your ESPHome configuration folder:

/config/
└── esphome/
    └── components/
        └── ezo_prs/
            ├── __init__.py
            ├── sensor.py
            ├── ezo_prs.h
            └── ezo_prs.cpp

Usage

A minimal device configuration:

i2c:
  - id: bus_a
    sda: 15
    scl: 16
    scan: true

sensor:
  - platform: ezo_prs
    i2c_id: bus_a
    id: pressure_sensor
    name: "Pressure Sensor"
    address: 0x6A          # default EZO-PRS I²C address
    update_interval: 5s
    pressure_unit: cmh2o   # psi | atm | bar | kpa | inh2o | cmh2o
    decimals: 3            # 0-3

    # Optional: surface device info / status into Home Assistant
    info_text_sensor: sensor_info
    status_text_sensor: sensor_status

text_sensor:
  - platform: template
    name: "Pressure Sensor Info"
    id: sensor_info
  - platform: template
    name: "Pressure Sensor Status"
    id: sensor_status

For a complete, real-world configuration with calibration buttons, status monitoring and unit switching, see example.yaml.

Configuration options

Option	Default	Description
pressure_unit	cmh2o	Measurement unit: psi, atm, bar, kpa, inh2o, cmh2o
decimals	3	Number of decimal places in readings (0-3)
address	0x6A	I²C address of the EZO-PRS sensor
update_interval	5s	How often to poll the sensor
info_text_sensor	optional	Existing text_sensor to receive device information
status_text_sensor	optional	Existing text_sensor to receive device status

The component is also a standard ESPHome sensor, so all common options (filters, accuracy_decimals, device_class, etc.) are available too.

Advanced usage — lambda methods

Every command is exposed as a method you can call from a lambda (for example from a template button):

button:
  - platform: template
    name: "Calibrate Zero"
    on_press:
      - lambda: 'id(pressure_sensor).calibrate_zero();'

  - platform: template
    name: "Clear Calibration"
    on_press:
      - lambda: 'id(pressure_sensor).clear_calibration();'

Available methods

Method	Description
calibrate_zero()	Calibrate the zero point
clear_calibration()	Clear all calibration data
check_calibration()	Check current calibration
get_status()	Request sensor status
set_offset(float)	Set the offset value
get_offset()	Read the current offset
clear_offset()	Clear the offset
set_led_state(bool)	Turn the on-board LED on / off
get_led_state()	Read the LED state
set_pressure_unit(string)	Change the active pressure unit
get_device_information()	Read device firmware / model information
send_custom(string)	Send any raw EZO command (e.g. "Cal,30")

WiFi & secrets

The example config keeps all credentials out of version control using ESPHome's !secret mechanism. To run it:

cp secrets.yaml.example secrets.yaml   # then edit with your own values

secrets.yaml is gitignored — never commit real credentials.

License

This project is licensed under the MIT License — see the LICENSE file.

Acknowledgements

• Atlas Scientific — for the EZO-PRS sensor
• ESPHome — for the framework

Contributing

Contributions are welcome. Feel free to open an issue or submit a pull request.