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ruanhaishen
Nodemcu Firmware
Commits
5a50f4e4
Commit
5a50f4e4
authored
Jan 25, 2015
by
Javier Yáñez
Browse files
Error checking added in the example. Functions description added
parent
3ede2de2
Changes
1
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Side-by-side
lua_modules/dht22/README.md
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5a50f4e4
# DHT22 module
# DHT22 module
This module is compatible with DHT22 and DHT21.
No need to use a resistor to connect the pin data of DHT22 to ESP8266.
## Example
## Example
```
lua
```
lua
PIN
=
4
-- data pin, GPIO2
PIN
=
4
-- data pin, GPIO2
...
@@ -9,14 +12,41 @@ dht22.read(PIN)
...
@@ -9,14 +12,41 @@ dht22.read(PIN)
t
=
dht22
.
getTemperature
()
t
=
dht22
.
getTemperature
()
h
=
dht22
.
getHumidity
()
h
=
dht22
.
getHumidity
()
-- temperature in degrees Celsius and Farenheit
if
h
==
-
1
then
print
(
"Temperature: "
..
(
t
/
10
)
..
"."
..
(
t
%
10
)
..
" deg C"
)
print
(
"Error reading from DHT22"
)
print
(
"Temperature: "
..
(
9
*
t
/
50
+
32
)
..
"."
..
(
9
*
t
/
5
%
10
)
..
" deg F"
)
else
-- temperature in degrees Celsius and Farenheit
print
(
"Temperature: "
..
(
t
/
10
)
..
"."
..
(
t
%
10
)
..
" deg C"
)
print
(
"Temperature: "
..
(
9
*
t
/
50
+
32
)
..
"."
..
(
9
*
t
/
5
%
10
)
..
" deg F"
)
-- humidity
-- humidity
print
(
"Humidity: "
..
(
h
/
10
)
..
"."
..
(
h
%
10
)
..
"%"
)
print
(
"Humidity: "
..
(
h
/
10
)
..
"."
..
(
h
%
10
)
..
"%"
)
end
-- release module
-- release module
dht22
=
nil
dht22
=
nil
package.loaded
[
"dht22"
]
=
nil
package.loaded
[
"dht22"
]
=
nil
```
```
## Functions
### read
read(pin)
Read humidity and temperature from DHT22.
**Parameters:**
*
pin - ESP8266 pin connect to data pin in DHT22
### 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 0.1ºC
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