add 18650-powered BME280 outdoor sensor

Connections:

D1 → SCL

D2 → SDA

D5 → VCC

D6 → CSB

station_cfg = {}

dofile("wifi.lua")

mqtt_host = "mqtt.derf0.net"

chip_id = node.chipid()

device_id = "esp8266_" .. chip_id

mqtt_prefix = "sensor/" .. device_id

mqttclient = mqtt.Client(device_id, 120)

print("https://wiki.chaosdorf.de/Sensorium")

print("ESP8266 " .. chip_id)

gpio.mode(6, gpio.OUTPUT)

gpio.mode(5, gpio.OUTPUT)

gpio.write(6, 1)

gpio.write(5, 1)

i2c.setup(0, 2, 1, i2c.SLOW)

if not bme280.setup() then

	print("BME280 setup failed")

end

--   150 kOhm resistor VCC -> A0

-- + 220 kOhm resistor A0 -> ADC

-- + 100 kOhm resistor ADC -> GND

-- -> 4.7V == 1023, 0V == 0

-- -> adc.read(0) / 1023 * (470 / 100) == VCC

-- -> adc.read(0) * 469 / 102 ~= VCC_mV

function get_battery_mv()

	return adc.read(0) * 439 / 102

end

function get_battery_percent(bat_mv)

	if bat_mv > 4100 then

		return 100

	end

	if bat_mv < 3400 then

		return 0

	end

	return (bat_mv - 3400) / 7

end

function connect_mqtt()

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

	print("Connecting to MQTT " .. mqtt_host)

	mqttclient:on("connect", hass_register)

	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.setmode(wifi.STATION)

	wifi.sta.config(station_cfg)

	wifi.sta.connect()

end

function publish_reading()

	local T, P, H, QNH = bme280.read(68)

	local bat_mv = get_battery_mv()

	local bat_percent = get_battery_percent(bat_mv)

	local rssi = wifi.sta.getrssi()

	if T == nil then

		print("BME280 readout failed")

		local json_str = string.format('{"battery_mv":%d,"battery_percent":%d,"rssi_dbm":%d}', bat_mv, bat_percent, rssi)

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

			naptime()

		end)

		return

	end

	local Tsgn = (T < 0 and -1 or 1)

	T = Tsgn*T

	local temp = string.format("%s%d.%02d", Tsgn<0 and "-" or "", T/100, T%100)

	local humi = string.format("%d.%03d", H/1000, H%1000)

	local pressure = string.format("%d.%03d", P/1000, P%1000)

	local sealevel = string.format("%d.%03d", QNH/1000, QNH%1000)

	local json_str = string.format('{"temperature_celsius":%s,"humidity_relpercent":%s,"pressure_hpa":%s,"pressure_sealevel_hpa":%s,"battery_mv":%d,"battery_percent":%d,"rssi_dbm":%d}', temp, humi, pressure, sealevel, bat_mv, bat_percent, rssi)

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

		naptime()

	end)

end

function hass_register()

	publish_reading()

end

--	local hass_device = string.format('{"connections":[["mac","%s"]],"identifiers":["%s"],"model":"ESP8266","name":"ESP8266 PM1006","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_pm2_5 = string.format('{%s,"name":"PM2.5","object_id":"%s_pm2_5","unique_id":"%s_pm2_5","icon":"mdi:air-filter","unit_of_measurement":"µg/m³","value_template":"{{value_json.pm2_5_ugm3}}"}', hass_entity_base, device_id, device_id)

--	local hass_rssi = string.format('{%s,"name":"RSSI","object_id":"%s_rssi","unique_id":"%s_rssi","icon":"mdi:wifi","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 .. "/pm2_5/config", hass_pm2_5, 0, 1, function(client)

--		mqttclient:publish("homeassistant/sensor/" .. device_id .. "/rssi/config", hass_rssi, 0, 1, function(client)

--			collectgarbage()

--			publish_reading()

--		end)

--	end)

--end

function naptime()

	print("Naptime")

	gpio.write(5, 0)

	gpio.write(6, 0)

	rtctime.dsleep(800 * 1000000)

end

go_to_sleep = tmr.create()

go_to_sleep:register(40 * 1000, tmr.ALARM_SEMI, naptime)

go_to_sleep:start()

connect_wifi()