From 10ccfc6ad23ebdb173e62ac2f89538b0ca47328d Mon Sep 17 00:00:00 2001 From: Martin Han Date: Sun, 5 Apr 2015 18:20:16 +0800 Subject: [PATCH] Add support to DHT11 and add some comments. --- lua_modules/dht22/dht_lib.lua | 237 ++++++++++++++++++++++++---------- 1 file changed, 166 insertions(+), 71 deletions(-) diff --git a/lua_modules/dht22/dht_lib.lua b/lua_modules/dht22/dht_lib.lua index 4b8ced7b..e1edf13a 100644 --- a/lua_modules/dht22/dht_lib.lua +++ b/lua_modules/dht22/dht_lib.lua @@ -1,90 +1,185 @@ -# DHTxx module +-- *************************************************************************** +-- DHTxx(11,21,22) module for ESP8266 with nodeMCU +-- +-- Written by Javier Yanez mod by Martin +-- but based on a script of Pigs Fly from ESP8266.com forum +-- +-- MIT license, http://opensource.org/licenses/MIT +-- *************************************************************************** -This module is compatible with DHT11, DHT21 and DHT22. -And is able to auto-select wheather you are using DHT11 or DHT2x +--Support list： +--DHT11 Tested ->read11 +--DHT21 Not Tested->read22 +--DHT22 Tested->read22 -No need to use a resistor to connect the pin data of DHT22 to ESP8266. +--==========================Module Part====================== +local moduleName = ... +local M = {} +_G[moduleName] = M +--==========================Local the UMI and TEMP=========== +local humidity +local temperature +--==========================Local the bitStream============== +local bitStream = {} -##Integer Verison[When using DHT11, Float version is useless...] -### Example -```lua -PIN = 4 -- data pin, GPIO2 +---------------------------Read bitStream from DHTXX-------------------------- +local function read(pin) -DHT= require("dht_lib") + local bitlength = 0 + humidity = 0 + temperature = 0 -DHT.read(PIN) - -t = DHT.getTemperature() -h = DHT.getHumidity() - -if h == nil then - print("Error reading from DHTxx") -else - -- temperature in degrees Celsius and Farenheit - - print("Temperature: "..((t-(t % 10)) / 10).."."..(t % 10).." deg C") - - print("Temperature: "..(9 * t / 50 + 32).."."..(9 * t / 5 % 10).." deg F") + -- Use Markus Gritsch trick to speed up read/write on GPIO + local gpio_read = gpio.read - -- humidity + + for j = 1, 40, 1 do + bitStream[j] = 0 + end - print("Humidity: "..((h - (h % 10)) / 10).."."..(h % 10).."%") + + + -- Step 1: send out start signal to DHT22 + gpio.mode(pin, gpio.OUTPUT) + gpio.write(pin, gpio.HIGH) + tmr.delay(100) + gpio.write(pin, gpio.LOW) + tmr.delay(20000) + gpio.write(pin, gpio.HIGH) + gpio.mode(pin, gpio.INPUT) + + -- Step 2: Receive bitStream from DHT11/22 + -- bus will always let up eventually, don't bother with timeout + while (gpio_read(pin) == 0 ) do end + local c=0 + while (gpio_read(pin) == 1 and c < 500) do c = c + 1 end + -- bus will always let up eventually, don't bother with timeout + while (gpio_read(pin) == 0 ) do end + c=0 + while (gpio_read(pin) == 1 and c < 500) do c = c + 1 end + + -- Step 3: DHT22 send data + for j = 1, 40, 1 do + while (gpio_read(pin) == 1 and bitlength < 10 ) do + bitlength = bitlength + 1 + end + bitStream[j] = bitlength + bitlength = 0 + -- bus will always let up eventually, don't bother with timeout + while (gpio_read(pin) == 0) do end + end +end +---------------------------Convert the bitStream into Number through DHT11 Ways-------------------------- +local function bit2DHT11() +--As for DHT11 40Bit is consisit of 5Bytes +--First byte->Humidity Data's Int part +--Sencond byte->Humidity Data's Float Part(Which should be empty) +--Third byte->Temp Data;s Intpart +--Forth byte->Temp Data's Float Part(Which should be empty) +--Fifth byte->SUM Byte, Humi+Temp + local checksum = 0 + local checksumTest + --DHT data acquired, process. + for i = 1, 8, 1 do -- Byte[0] + if (bitStream[i] > 3) then + humidity = humidity + 2 ^ (8 - i) + end + end + for i = 1, 8, 1 do -- Byte[2] + if (bitStream[i + 16] > 3) then + temperature = temperature + 2 ^ (8 - i) + end + end + for i = 1, 8, 1 do --Byte[4] + if (bitStream[i + 32] > 3) then + checksum = checksum + 2 ^ (8 - i) + end + end + + if(checksum ~= humidity+temperature) then + humidity = nil + temperature = nil + end + +end +---------------------------Convert the bitStream into Number through DHT22 Ways-------------------------- +local function bit2DHT22() +--As for DHT22 40Bit is consisit of 5Bytes +--First byte->Humidity Data's High Bit +--Sencond byte->Humidity Data's Low Bit(And if over 0x8000, use complement) +--Third byte->Temp Data's High Bit +--Forth byte->Temp Data's Low Bit +--Fifth byte->SUM Byte + local checksum = 0 + local checksumTest + --DHT data acquired, process. + for i = 1, 16, 1 do + if (bitStream[i] > 3) then + humidity = humidity + 2 ^ (16 - i) + end + end + for i = 1, 16, 1 do + if (bitStream[i + 16] > 3) then + temperature = temperature + 2 ^ (16 - i) + end + end + for i = 1, 8, 1 do + if (bitStream[i + 32] > 3) then + checksum = checksum + 2 ^ (8 - i) + end + end + + checksumTest = (bit.band(humidity, 0xFF) + bit.rshift(humidity, 8) + bit.band(temperature, 0xFF) + bit.rshift(temperature, 8)) + checksumTest = bit.band(checksumTest, 0xFF) + + if temperature > 0x8000 then + -- convert to negative format + temperature = -(temperature - 0x8000) + end + + -- conditions compatible con float point and integer + if (checksumTest - checksum >= 1) or (checksum - checksumTest >= 1) then + humidity = nil + end end --- release module -DHT = nil -package.loaded["dht_lib"]=nil -``` -##Float Verison -###Example -```lua -PIN = 4 -- data pin, GPIO2 +---------------------------Check out the data-------------------------- +----Auto Select the DHT11/DHT22 By check the byte[1] && byte[3]AND --- +---------------Which is empty when using DHT11------------------------- +function M.read(pin) -DHT= require("dht_lib") + read(pin) -DHT.read(PIN) + local byte_1 = 0 + local byte_2 = 0 -t = DHT.getTemperature() -h = DHT.getHumidity() + for i = 1, 8, 1 do -- Byte[1] + if (bitStream[i+8] > 3) then + byte_1 = byte_1 + 2 ^ (8 - i) + end + end -if h == nil then - print("Error reading from DHT11/22") -else - -- temperature in degrees Celsius and Farenheit - -- floating point and integer version: + for i = 1, 8, 1 do -- Byte[1] + if (bitStream[i+24] > 3) then + byte_2 = byte_2 + 2 ^ (8 - i) + end + end + + if byte_1==0 and byte_2 == 0 then + bit2DHT11() + else + bit2DHT22() + end - print("Temperature: "..(t/10).." deg C") - print("Temperature: "..(9 * t / 50 + 32).." deg F") - - -- humidity - print("Humidity: "..(h/10).."%") end --- release module -DHT = nil -package.loaded["dht_lib"]=nil -``` -## Functions -###read -read(pin) -Read humidity and temperature from DHTxx(11,21,22...). -**Parameters:** +function M.getTemperature() + return temperature +end -* pin - ESP8266 pin connect to data pin - -### getHumidity -getHumidity() -Returns the humidity of the last reading. - -**Returns:** -* last humidity reading in per thousand - -### getTemperature -getTemperature() -Returns the temperature of the last reading. - -**Returns:** -* last temperature reading in(dht22) 0.1ºC (dht11)1ºC -* +function M.getHumidity() + return humidity +end +return M