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ruanhaishen
Nodemcu Firmware
Commits
c21dea9d
Commit
c21dea9d
authored
Apr 05, 2015
by
Martin Han
Browse files
Fix DHT11 10times BUG, add auto-select feature
parent
b1287756
Changes
1
Hide whitespace changes
Inline
Side-by-side
lua_modules/dht_lib/dht_lib.lua
0 → 100644
View file @
c21dea9d
-- ***************************************************************************
-- 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
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