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+# ESP8266 Lua/NodeMCU module for VEML6075 UV irradiance sensors
+
+This repository contains an ESP8266 NodeMCU Lua module (`sen5x.lua`) as well as
+MQTT / HomeAssistant / InfluxDB integration example (`init.lua`) for
+**VEML6075** UV irradiance sensors connected via I²C.
+
+## Dependencies
+
+veml6075.lua has been tested with Lua 5.1 on NodeMCU firmware 3.0.1 (Release
+202112300746, integer build). It requires the following modules.
+
+* i2c
+
+The MQTT HomeAssistant integration in init.lua additionally needs the following
+modules.
+
+* gpio
+* mqtt
+* node
+* tmr
+* wifi
+
+## Setup
+
+Connect the VEML6075 sensor to your ESP8266/NodeMCU board as follows.
+
+* VEML6075 GND → ESP8266/NodeMCU GND
+* VEML6075 VCC → ESP8266/NodeMCU 3V3
+* VEML6075 SDA → NodeMCU D1 (ESP8266 GPIO5)
+* VEML6075 SCL → NodeMCU D2 (ESP8266 GPIO4)
+
+If you use different pins for SCL and SDA, you need to adjust the 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 VEML6075 connection.
+
+## Usage
+
+Copy **veml6075.lua** to your NodeMCU board and set it up as follows.
+
+```lua
+veml6075 = require("veml6075")
+i2c.setup(0, 1, 2, i2c.SLOW)
+veml6075.start()
+
+-- can be called with up to 10 Hz
+function some_timer_callback()
+	if veml6075.read() then
+		-- All values are float
+		-- veml6075.uva   : UV-A irradiance [µW/cm²]
+		-- veml6075.uvb   : UV-B irradiance [µW/cm²]
+		-- veml6075.uva_i : UV-A index
+		-- veml6075.uvb_i : UV-B index
+	end
+end
+```
+
+## Application Example
+
+**init.lua** is an example application with HomeAssistant integration.
+To use it, you need to create a **config.lua** file with WiFI and MQTT settings:
+
+```lua
+station_cfg = {ssid = "...", pwd = "..."}
+mqtt_host = "..."
+```
+
+Optionally, it can also publish readings to InfluxDB.
+To do so, configure URL and attribute:
+
+```lua
+influx_url = "..."
+influx_attr = "..."
+```
+
+Readings will be published as `veml6075[influx_attr] uva_uwcm2=%f,uvb_uwcm2=%f,uv_index=%f`.
+So, unless `influx_attr = ''`, it must start with a comma, e.g. `influx_attr = ',device=' .. device_id`.