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| -rw-r--r-- | .gitignore | 1 | ||||
| -rw-r--r-- | README.md | 50 | ||||
| -rw-r--r-- | init.lua | 102 | ||||
| -rw-r--r-- | scd4x.lua | 45 |
4 files changed, 198 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..338c30b --- /dev/null +++ b/.gitignore @@ -0,0 +1 @@ +config.lua diff --git a/README.md b/README.md new file mode 100644 index 0000000..5ccf55a --- /dev/null +++ b/README.md @@ -0,0 +1,50 @@ +# ESP8266 Lua/NodeMCU module for Sensirion SCD40/SCD41 CO₂ sensor + +This repository contains a Lua module (`scd4x.lua`) as well as +MQTT-based HomeAssistant integration (`init.lua`) for **Sensirion SCD40/SCD41** +CO₂ sensors. + +## Dependencies + +scd4x.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 +* uart +* wifi + +## Usage + +Copy **scd4x.lua** to your NodeMCU board and set it up as follows. + +```lua +scd4x = require("scd4x") +i2c.setup(0, sda_pin, scl_pin, i2c.SLOW) +scd4x.start() + +-- can be called with up to 1 Hz +function some_timer_callback() + local co2, raw_temp, raw_humi = scd4x.read() + if co2 == nil then + print("SCD4x error") + else + -- CO₂[ppm] == co2, Temperature[°c] == raw_temp/2¹⁶ - 45, Humidity[%] == raw_humi/2¹⁶ + 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 = "..." +``` diff --git a/init.lua b/init.lua new file mode 100644 index 0000000..8904f95 --- /dev/null +++ b/init.lua @@ -0,0 +1,102 @@ +station_cfg = {} +dofile("config.lua") + +delayed_restart = tmr.create() +push_timer = tmr.create() +chip_id = node.chipid() +device_id = "esp8266_" .. chip_id +mqtt_prefix = "sensor/" .. device_id +mqttclient = mqtt.Client(device_id, 120) + + +print("ESP8266 " .. chip_id) + +ledpin = 4 +gpio.mode(ledpin, gpio.OUTPUT) +gpio.write(ledpin, 0) + +scd4x = require("scd4x") +i2c.setup(0, 2, 1, i2c.SLOW) + +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) + if not scd4x.start() then + print("SCD4x initialization error") + end + publishing = true + mqttclient:publish(mqtt_prefix .. "/state", "online", 0, 1, function(client) + publishing = false + push_data() + end) +end + +function connect_mqtt() + print("IP address: " .. wifi.sta.getip()) + print("Connecting to MQTT " .. mqtt_host) + delayed_restart:stop() + mqttclient:on("connect", hass_register) + 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 push_data() + local co2, raw_temp, raw_humi = scd4x.read() + if co2 == nil then + print("SCD4x error") + else + local json_str = string.format('{"co2_ppm": %d, "temperature_degc": %d.%d, "humidity_relpercent": %d.%d, "rssi_dbm": %d}', co2, raw_temp/65536 - 45, (raw_temp%65536)/6554, raw_humi/65536, (raw_humi%65536)/6554, 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 + push_timer:start() +end + +function hass_register() + local hass_device = string.format('{"connections":[["mac","%s"]],"identifiers":["%s"],"model":"ESP8266","name":"ESP8266 with SCD4x","manufacturer":"DIY"}', wifi.sta.getmac(), device_id) + local hass_entity_base = string.format('"device":%s,"state_topic":"%s/data","expire_after":600', hass_device, mqtt_prefix) + local hass_co2 = string.format('{%s,"name":"CO₂","object_id":"%s_co2","unique_id":"%s_co2","device_class":"carbon_dioxide","unit_of_measurement":"ppm","value_template":"{{value_json.co2_ppm}}"}', hass_entity_base, device_id, device_id) + local hass_temp = string.format('{%s,"name":"Temperature","object_id":"%s_temperature","unique_id":"%s_temperature","device_class":"temperature","unit_of_measurement":"°c","value_template":"{{value_json.temperature_degc}}"}', hass_entity_base, device_id, device_id) + local hass_humi = string.format('{%s,"name":"Humidity","object_id":"%s_humidity","unique_id":"%s_humidity","device_class":"humidity","unit_of_measurement":"%%","value_template":"{{value_json.humidity_relpercent}}"}', hass_entity_base, device_id, device_id) + local hass_rssi = string.format('{%s,"name":"RSSI","object_id":"%s_rssi","unique_id":"%s_rssi","device_class":"signal_strength","unit_of_measurement":"dBm","value_template":"{{value_json.rssi_dbm}}","entity_category":"diagnostic"}', hass_entity_base, device_id, device_id) + + mqttclient:publish("homeassistant/sensor/" .. device_id .. "/co2/config", hass_co2, 0, 1, function(client) + mqttclient:publish("homeassistant/sensor/" .. device_id .. "/temperature/config", hass_temp, 0, 1, function(client) + mqttclient:publish("homeassistant/sensor/" .. device_id .. "/humidity/config", hass_humi, 0, 1, function(client) + mqttclient:publish("homeassistant/sensor/" .. device_id .. "/rssi/config", hass_rssi, 0, 1, function(client) + collectgarbage() + setup_client() + end) + end) + end) + end) +end + +delayed_restart:register(20 * 1000, tmr.ALARM_SINGLE, node.restart) +push_timer:register(20 * 1000, tmr.ALARM_SEMI, push_data) + +connect_wifi() diff --git a/scd4x.lua b/scd4x.lua new file mode 100644 index 0000000..47495e2 --- /dev/null +++ b/scd4x.lua @@ -0,0 +1,45 @@ +local scd4x = {} +local device_address = 0x62 + +scd4x.bus_id = 0 + +function scd4x.start() + i2c.start(scd4x.bus_id) + if not i2c.address(scd4x.bus_id, device_address, i2c.TRANSMITTER) then + return false + end + i2c.write(scd4x.bus_id, {0x21, 0xb1}) + i2c.stop(scd4x.bus_id) + return true +end + +function scd4x.stop() + i2c.start(scd4x.bus_id) + if not i2c.address(scd4x.bus_id, device_address, i2c.TRANSMITTER) then + return false + end + i2c.write(scd4x.bus_id, {0x3f, 0x86}) + i2c.stop(scd4x.bus_id) + return true +end + +function scd4x.read() + i2c.start(scd4x.bus_id) + if not i2c.address(scd4x.bus_id, device_address, i2c.TRANSMITTER) then + return nil + end + i2c.write(scd4x.bus_id, {0xec, 0x05}) + i2c.stop(scd4x.bus_id) + i2c.start(scd4x.bus_id) + if not i2c.address(scd4x.bus_id, device_address, i2c.RECEIVER) then + return nil + end + local data = i2c.read(scd4x.bus_id, 9) + i2c.stop(scd4x.bus_id) + local co2 = string.byte(data, 1) * 256 + string.byte(data, 2) + local temp_raw = 175 * (string.byte(data, 4) * 256 + string.byte(data, 5)) + local humi_raw = 100 * (string.byte(data, 7) * 256 + string.byte(data, 8)) + return co2, temp_raw, humi_raw +end + +return scd4x |