initial commit

config.lua

# ESP8266 Lua/NodeMCU module for Vindriktning PM1006 particle monitor

This repository contains a Lua module (`pm1006.lua`) as well as ESP8266/NodeMCU

MQTT gateway application example (`init.lua`) for the **PM1006** particulate

matter (PM2.5) sensor found in IKEA Vindriktning.

## Dependencies

pm1006.lua has been tested with Lua 5.1 on NodeMCU firmware 3.0.1 (Release

202112300746, integer build). Most practical applications (such as the example

in init.lua) require the following modules.

* gpio

* mqtt

* node

* softuart

* tmr

* uart

* wifi

## Setup

Connect the PM1006 sensor to your ESP8266/NodeMCU board as [documented by Hypfer](https://github.com/Hypfer/esp8266-vindriktning-particle-sensor).

If you use a different UART pin, you need to adjust the softuart.setup call in

the examples provided in this repository to reflect that change. Keep in mind

that some ESP8266 pins must have well-defined logic levels at boot time and may

therefore be unsuitable for PM1006 connection.

## Usage

Copy **pm1006.lua** to your NodeMCU board and set it up as follows.

```lua

pm1006 = require("pm1006")

port = softuart.setup(9600, nil, 2)

port:on("data", 20, uart_callback)

function uart_callback(data)

	local pm2_5 = pm1006.parse_frame(data)

	if pm25i ~= nil then

		-- pm2_5 contains PM2.5 value in µg/m³

	else

		-- invalid frame header or checksum

	end

end

```

See **init.lua** for an example. To use it, you need to create a **config.lua** file with WiFI and MQTT settings:

```lua

station_cfg.ssid = "..."

station_cfg.pwd = "..."

mqtt_host = "..."

```

station_cfg = {}

dofile("config.lua")

delayed_restart = tmr.create()

chipid = node.chipid()

mqtt_prefix = "sensor/esp8266_" .. chipid

mqttclient = mqtt.Client("esp8266_" .. chipid, 120)

print("ESP8266 " .. chipid)

ledpin = 4

gpio.mode(ledpin, gpio.OUTPUT)

gpio.write(ledpin, 0)

pm1006 = require("pm1006")

function log_restart()

	print("Network error " .. wifi.sta.status() .. ". Restarting in 20 seconds.")

	delayed_restart:start()

end

function setup_client()

	print("Connected")

	gpio.write(ledpin, 1)

	publishing = true

	mqttclient:publish(mqtt_prefix .. "/state", "online", 0, 1, function(client)

		publishing = false

	end)

	port = softuart.setup(9600, nil, 2)

	port:on("data", 20, uart_callback)

end

function connect_mqtt()

	print("IP address: " .. wifi.sta.getip())

	print("Connecting to MQTT " .. mqtt_host)

	delayed_restart:stop()

	mqttclient:on("connect", setup_client)

	mqttclient:on("offline", log_restart)

	mqttclient:lwt(mqtt_prefix .. "/state", "offline", 0, 1)

	mqttclient:connect(mqtt_host)

end

function connect_wifi()

	print("WiFi MAC: " .. wifi.sta.getmac())

	print("Connecting to ESSID " .. station_cfg.ssid)

	wifi.eventmon.register(wifi.eventmon.STA_GOT_IP, connect_mqtt)

	wifi.eventmon.register(wifi.eventmon.STA_DHCP_TIMEOUT, log_restart)

	wifi.eventmon.register(wifi.eventmon.STA_DISCONNECTED, log_restart)

	wifi.setmode(wifi.STATION)

	wifi.sta.config(station_cfg)

	wifi.sta.connect()

end

function uart_callback(data)

	local pm2_5 = pm1006.parse_frame(data)

	if pm2_5 == nil then

		print("Invalid PM1006 frame")

		return

	else

		local json_str = string.format('{"pm25_ugm3": %d, "rssi_dbm": %d}', pm2_5, wifi.sta.getrssi())

		if not publishing then

			publishing = true

			gpio.write(ledpin, 0)

			mqttclient:publish(mqtt_prefix .. "/data", json_str, 0, 0, function(client)

				publishing = false

				gpio.write(ledpin, 1)

				collectgarbage()

			end)

		end

	end

end

delayed_restart:register(20 * 1000, tmr.ALARM_SINGLE, node.restart)

connect_wifi()

local pm1006 = {}

function pm1006.parse_frame(data)

	if string.byte(data, 1) ~= 0x16 or string.byte(data, 2) ~= 0x11 or string.byte(data, 3) ~= 0x0b then

		-- invalid header

		return nil

	end

	local checksum = 0

	for i = 1, 20 do

		checksum = (checksum + string.byte(data, i)) % 256

	end

	if checksum ~= 0 then

		-- invalid checksum

		return nil

	end

	local pm2_5 = string.byte(data, 6) * 256 + string.byte(data, 7)

	return pm2_5

end

return pm1006