235
Chapter 21 Hygrothermograph DHT11
The following is the program code:
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i m port
RPi
.
GPIO
a s
GPIO
i m port
time
i m port
Freenove_DHT
a s
DHT
DHTPin
=
11
#define the pin of DHT11
d e f
loop
( ):
dht
=
DHT
.
DHT
(
DHTPin
)
#create a DHT class object
sumCnt
=
0
#number of reading times
w h ile
(
True
):
sumCnt
+ =
1
#counting number of reading times
chk
=
dht
.
readDHT11
()
#read DHT11 and get a return value. Then determine
whether data read is normal according to the return value.
p r int
(
"The sumCnt is : %d, \t chk : %d"
% (
sumCnt
,
chk
))
i f
(
chk
i s
dht
.
DHTLIB_OK
):
#read DHT11 and get a return value. Then
determine whether data read is normal according to the return value.
p r int
(
"DHT11,OK!"
)
e l if
(
chk
i s
dht
.
DHTLIB_ERROR_CHECKSUM
):
#data check has errors
p r int
(
"DHTLIB_ERROR_CHECKSUM!!"
)
e l if
(
chk
i s
dht
.
DHTLIB_ERROR_TIMEOUT
):
#reading DHT times out
p r int
(
"DHTLIB_ERROR_TIMEOUT!"
)
e l se
:
#other errors
p r int
(
"Other error!"
)
p r int
(
"Humidity : %.2f, \t Temperature : %.2f \n"
% (
dht
.
humidity
,
dht
.
temperature
))
time
.
sleep
(
2
)
i f
__name__
= =
'__main__'
:
p r int
(
'Program is starting ... '
)
t r y
:
loop
( )
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