Add support to DHT11 and add some comments.

Change function names.
read->-read11() support DHT11
        ->read22() support DHT21 DHT22
This commit is contained in:
Martin Han 2015-04-03 23:34:12 +08:00
parent d8f2c2ba34
commit 4ca371f473
1 changed files with 66 additions and 11 deletions

View File

@ -1,34 +1,43 @@
-- *************************************************************************** -- ***************************************************************************
-- DHT22 module for ESP8266 with nodeMCU -- DHTxx(11,21,22) module for ESP8266 with nodeMCU
-- --
-- Written by Javier Yanez -- Written by Javier Yanez mod by Martin
-- but based on a script of Pigs Fly from ESP8266.com forum -- but based on a script of Pigs Fly from ESP8266.com forum
-- --
-- MIT license, http://opensource.org/licenses/MIT -- MIT license, http://opensource.org/licenses/MIT
-- *************************************************************************** -- ***************************************************************************
--Support list
--DHT11 Tested ->read11
--DHT21 Not Tested->read22
--DHT22 Tested->read22
--==========================Module Part======================
local moduleName = ... local moduleName = ...
local M = {} local M = {}
_G[moduleName] = M _G[moduleName] = M
--==========================Local the UMI and TEMP===========
local humidity local humidity
local temperature local temperature
--==========================Local the bitStream==============
local bitStream = {}
function M.read(pin) ---------------------------Read bitStream from DHTXX--------------------------
local checksum local function read(pin)
local checksumTest
local bitlength = 0
humidity = 0 humidity = 0
temperature = 0 temperature = 0
checksum = 0
-- Use Markus Gritsch trick to speed up read/write on GPIO -- Use Markus Gritsch trick to speed up read/write on GPIO
local gpio_read = gpio.read local gpio_read = gpio.read
local bitStream = {}
for j = 1, 40, 1 do for j = 1, 40, 1 do
bitStream[j] = 0 bitStream[j] = 0
end end
local bitlength = 0
-- Step 1: send out start signal to DHT22 -- Step 1: send out start signal to DHT22
gpio.mode(pin, gpio.OUTPUT) gpio.mode(pin, gpio.OUTPUT)
@ -39,7 +48,7 @@ function M.read(pin)
gpio.write(pin, gpio.HIGH) gpio.write(pin, gpio.HIGH)
gpio.mode(pin, gpio.INPUT) gpio.mode(pin, gpio.INPUT)
-- Step 2: DHT22 send response signal -- Step 2: Receive bitStream from DHT11/22
-- bus will always let up eventually, don't bother with timeout -- bus will always let up eventually, don't bother with timeout
while (gpio_read(pin) == 0 ) do end while (gpio_read(pin) == 0 ) do end
local c=0 local c=0
@ -59,8 +68,53 @@ function M.read(pin)
-- bus will always let up eventually, don't bother with timeout -- bus will always let up eventually, don't bother with timeout
while (gpio_read(pin) == 0) do end while (gpio_read(pin) == 0) do end
end end
end
---------------------------Convert the bitStream into Number through DHT11 Ways--------------------------
function M.read11(pin)
--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
read(pin)
local checksum = 0
local checksumTest
--DHT data acquired, process. --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--------------------------
function M.read22( pin )
--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
read(pin)
local checksum = 0
local checksumTest
--DHT data acquired, process.
for i = 1, 16, 1 do for i = 1, 16, 1 do
if (bitStream[i] > 3) then if (bitStream[i] > 3) then
humidity = humidity + 2 ^ (16 - i) humidity = humidity + 2 ^ (16 - i)
@ -91,6 +145,7 @@ function M.read(pin)
end end
end end
---------------------------Check out the data--------------------------
function M.getTemperature() function M.getTemperature()
return temperature return temperature
end end