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This repository contains an ESP8266 NodeMCU Lua module (`sen5x.lua`) as well as

MQTT / HomeAssistant / InfluxDB integration example (`init.lua`) for

**Sensirion SEN5x** particulate matter, VOC, and NOx sensors.

![](https://finalrewind.org/projects/esp8266-nodemcu-sen5x/media/preview.jpg)

**Sensirion SEN5x** I²C particulate matter, VOC, and NOx sensors connected via

I²C.

## Dependencies

sen5x.lua has been tested with Lua 5.1 on NodeMCU firmware 3.0.1 (Release

202112300746, integer build). It requires the following modules.

* i2c

* bit

* i2c

The MQTT HomeAssistant integration in init.lua additionally needs the following

modules.

* mqtt

* node

* tmr

* uart

* wifi

## Setup

SDA and SCL must have external pull-up resistors to 3V3.

If you use different pins for SDA and SCL, you need to adjust the

softuart.setup call in the examples provided in this repository to reflect

i2c.setup call in the examples provided in this repository to reflect

those changes. Keep in mind that some ESP8266 pins must have well-defined logic

levels at boot time and may therefore be unsuitable for SEN5x connection.

function read_data()

	if sen5x.read() then

		print(string.format("PM1: %d.%01d µg/m³", sen5x.pm1/10, sen5x.pm1%10))

		-- Available values depend on sensor type (SEN50/SEN54/SEN55)

		-- Unsupported readings are nil

		-- sen5x.pm1         : pm1/10   == PM1.0 concentration [µg/m³]

		-- sen5x.pm2_5       : pm2_5/10 == PM2.5 concentration [µg/m³]

		-- sen5x.pm4         : pm4/10   == PM4.0 concentration [µg/m³]

		-- sen5x.pm10        : pm10/10  == PM10  concentration [µg/m³]

		-- sen5x.humidity    : humidity/100 == Humidity [%]

		-- sen5x.temperature : temperature/200 == Temperature [°c]

		-- sen5x.voc         : voc/10 == VOC [?]

		-- sen5x.nox         : nox/10 == NOx [?]

	end

end

```

To use it, you need to create a **config.lua** file with WiFi and MQTT settings:

```lua

station_cfg.ssid = "..."

station_cfg.pwd = "..."

station_cfg = {ssid = "...", pwd = "..."}

mqtt_host = "..."

```

influx_attr = "..."

```

Readings will be stored as `sen5x,[influx_attr] pm1_ugm3=...,pm2_5_ugm3=...,...`

Readings will be published as `sen5x[influx_attr] pm1_ugm3=%d.%01d,pm2_5_ugm3=%d.%01d,pm4_ugm3=%d.%01d,pm10_ugm3=%d.%01d,humidity_relpercent=%d.%01d,temperature_celsius=%d.%01d,voc=%d.%01d,nox=%d.%01d,`

(or a subset thereof, depending on whether a SEN50/SEN54/SEN55 is connected).

So, unless `influx_attr = ''`, it must start with a comma, e.g. `influx_attr = ',device=' .. device_id`.

## Images

![](https://finalrewind.org/projects/esp8266-nodemcu-sen5x/media/preview.jpg)

station_cfg = {}

publishing_mqtt = false

publishing_http = false

dofile("config.lua")

print("ESP8266 " .. chip_id)

print("SEN5x " .. chip_id)

ledpin = 4

gpio.mode(ledpin, gpio.OUTPUT)