From c21dea9d8eca30d444449c9af1b6c6edce042ca1 Mon Sep 17 00:00:00 2001 From: Martin Han Date: Sun, 5 Apr 2015 23:23:18 +0800 Subject: [PATCH] Fix DHT11 10times BUG, add auto-select feature --- lua_modules/dht_lib/dht_lib.lua | 185 ++++++++++++++++++++++++++++++++ 1 file changed, 185 insertions(+) create mode 100644 lua_modules/dht_lib/dht_lib.lua diff --git a/lua_modules/dht_lib/dht_lib.lua b/lua_modules/dht_lib/dht_lib.lua new file mode 100644 index 00000000..e1edf13a --- /dev/null +++ b/lua_modules/dht_lib/dht_lib.lua @@ -0,0 +1,185 @@ +-- *************************************************************************** +-- 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 +-- *************************************************************************** + +--Support list： +--DHT11 Tested ->read11 +--DHT21 Not Tested->read22 +--DHT22 Tested->read22 + +--==========================Module Part====================== +local moduleName = ... +local M = {} +_G[moduleName] = M +--==========================Local the UMI and TEMP=========== +local humidity +local temperature +--==========================Local the bitStream============== +local bitStream = {} + +---------------------------Read bitStream from DHTXX-------------------------- +local function read(pin) + + local bitlength = 0 + humidity = 0 + temperature = 0 + + -- Use Markus Gritsch trick to speed up read/write on GPIO + local gpio_read = gpio.read + + + for j = 1, 40, 1 do + bitStream[j] = 0 + end + + + + -- 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 + +---------------------------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) + + read(pin) + + local byte_1 = 0 + local byte_2 = 0 + + for i = 1, 8, 1 do -- Byte[1] + if (bitStream[i+8] > 3) then + byte_1 = byte_1 + 2 ^ (8 - i) + end + end + + 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 + +end + + +function M.getTemperature() + return temperature +end + +function M.getHumidity() + return humidity +end + +return M