diff options
| -rw-r--r-- | README.md | 8 | ||||
| -rw-r--r-- | init.lua | 10 | ||||
| -rw-r--r-- | mh-z19.lua | 37 |
3 files changed, 28 insertions, 27 deletions
@@ -41,17 +41,17 @@ levels at boot time and may therefore be unsuitable for MH-Z19 connection. Copy **mh-z19.lua** to your NodeMCU board and set it up as follows. ```lua -mhz19 = require("mh-z19") +mh_z19 = require("mh-z19") port = softuart.setup(9600, 1, 2) port:on("data", 9, uart_callback) function uart_callback(data) - if sds011.parse_frame(data) then - -- mhz19.co2 contains the CO₂ concentration in ppm + if mh_z19.parse_frame(data) then + -- mh_z19.co2 contains the CO₂ concentration in ppm end end -port:write(mhz19.query()) +port:write(mhz19.c_query) ``` ## Application Example @@ -16,7 +16,7 @@ ledpin = 4 gpio.mode(ledpin, gpio.OUTPUT) gpio.write(ledpin, 0) -mhz19 = require("mh-z19") +mh_z19 = require("mh-z19") poll = tmr.create() @@ -58,13 +58,13 @@ function connect_wifi() end function uart_callback(data) - if not mhz19.parse_frame(data) then + if not mh_z19.parse_frame(data) then print("Invalid MH-Z19 frame") return end - local json_str = string.format('{"rssi_dbm":%d,"co2_ppm":"%d"}', wifi.sta.getrssi(), mhz19.co2) - local influx_str = string.format("co2_ppm=%d", mhz19.co2) + local json_str = string.format('{"rssi_dbm":%d,"co2_ppm":"%d"}', wifi.sta.getrssi(), mh_z19.co2) + local influx_str = string.format("co2_ppm=%d", mh_z19.co2) if not publishing_mqtt then watchdog:start(true) @@ -94,7 +94,7 @@ function publish_influx(payload) end function query_data() - port:write(mhz19.query()) + port:write(mh_z19.c_query) end function hass_register() @@ -1,28 +1,29 @@ -local mhz19 = {} +local mh_z19 = {} -local c_read = string.char(0xff, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x79) +mh_z19.c_query = string.char(0xff, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x79) -mhz19.co2 = nil -mhz19.temp = nil -mhz19.tt = nil -mhz19.ss = nil -mhz19.uu = nil +mh_z19.co2 = nil +mh_z19.temp = nil +mh_z19.abc_count = nil +mh_z19.abc_ticks = nil -function mhz19.query() - return c_read +function checksum(b1, b2, b3, b4, b5, b6, b7) + return 0xff - ((b1 + b2 + b3 + b4 + b5 + b6 + b7) % 0x100) + 1 end -function mhz19.parse_frame(data) - local head, cmd, co2h, co2l, temp, tt, ss, uh, ul = struct.unpack("BBBBBBBBB", data) - if head ~= 0xff or cmd ~= 0x86 then +function mh_z19.parse_frame(data) + local start, cmd, co2h, co2l, temp, u1, abc_ticks, abc_count, cksum = struct.unpack("BBBBBBBBB", data) + if start ~= 0xff or cmd ~= 0x86 then return false end - mhz19.co2 = co2h * 256 + co2l - mhz19.temp = temp - 40 - mhz19.tt = tt - mhz19.ss = ss - mhz19.uu = uh * 256 + ul + if checksum(cmd, co2h, co2l, temp, u1, abc_ticks, abc_count) ~= cksum then + return false + end + mh_z19.co2 = co2h * 256 + co2l + mh_z19.temp = temp - 40 + mh_z19.abc_ticks = abc_ticks + mh_z19.abc_count = abc_count return true end -return mhz19 +return mh_z19 |