diff options
| -rw-r--r-- | README.md | 50 | ||||
| -rw-r--r-- | init.lua | 3 |
2 files changed, 41 insertions, 12 deletions
@@ -1,8 +1,8 @@ -# ESP8266 Lua/NodeMCU module for Sensirion SCD40/SCD41 CO₂ sensor +# ESP8266 Lua/NodeMCU module for Sensirion SCD4x CO₂ sensors This repository contains an ESP8266 NodeMCU Lua module (`scd4x.lua`) as well as MQTT / HomeAssistant / InfluxDB integration example (`init.lua`) for -**Sensirion SCD40/SCD41** CO₂ sensors. +**Sensirion SCD4x** CO₂ sensors connected via I²C. ## Dependencies @@ -18,33 +18,63 @@ modules. * mqtt * node * tmr -* uart * wifi +## Setup + +Connect the SCD4x sensor to your ESP8266/NodeMCU board as follows. + +* SCD4x GND → ESP8266/NodeMCU GND +* SCD4x 3V3 → ESP8266/NodeMCU 3V3 +* SCD4x SCL → NodeMCU D1 (ESP8266 GPIO4) +* SCD4x SDA → NodeMCU D2 (ESP8266 GPIO5) + +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 +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 SCD4x connection. + ## 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) +i2c.setup(0, 2, 1, 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") + if co2 ~= nil then + -- co2 : CO₂ concentration [ppm] + -- raw_temp : raw_temp/2¹⁶ - 45 == Temperature [°c] + -- raw_humi : raw_humi/2¹⁶ == Humidity [%] else - -- CO₂[ppm] == co2, Temperature[°c] == raw_temp/2¹⁶ - 45, Humidity[%] == raw_humi/2¹⁶ + print("SCD4x error") end end ``` -See **init.lua** for an example. To use it, you need to create a **config.lua** file with WiFI and MQTT settings: +## 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 = "..." -station_cfg.pwd = "..." +station_cfg = {ssid = "...", pwd = "..."} mqtt_host = "..." ``` + +Optionally, it can also publish readings to an InfluxDB. +To do so, configure URL and attribute: + +```lua +influx_url = "..." +influx_attr = "..." +``` + +Readings will be published as `scd4x[influx_attr] co2_ppm=%d,temperature_degc=%d.%d,humidity_relpercent=%d.%d`. +So, unless `influx_attr = ''`, it must start with a comma, e.g. `influx_attr = ',device=' .. device_id`. @@ -1,4 +1,3 @@ -station_cfg = {} publishing_mqtt = false publishing_http = false @@ -11,7 +10,7 @@ mqttclient = mqtt.Client(device_id, 120) dofile("config.lua") -print("ESP8266 " .. chip_id) +print("SCD4x " .. chip_id) ledpin = 4 gpio.mode(ledpin, gpio.OUTPUT) |