blob: e6cd9fb02d7fc6d9ec871b1c64ac9b666c6af218 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
|
#!/bin/zsh
addr=0x5c
# Wait for AM2320 to wake up
# (it automatically goes idle after ~2 seconds without I2C activity)
while ! vusb-i2cset ${addr} 3 0 4 2> /dev/null; do
echo -n .
done
# Also retry wakeup in case of errors
while ! data=($(vusb-i2cget 0x5c 8 2> /dev/null)); do
echo -n .
while ! vusb-i2cset ${addr} 3 0 4 2> /dev/null; do
echo -n .
done
done
echo
if (( data[1] != 3 )); then
echo "Error: Expected return code 3 (read register), got code $data[1]" >&2
exit 1
fi
if (( data[2] != 4 )); then
echo "Error: Expected 4 data bytes, got $data[2]" >&2
exit 1
fi
(( checksum = 0xffff ))
for i in {1..6}; do
(( checksum ^= data[i] ))
for j in {1..8}; do
if (( checksum & 0x01 )); then
(( checksum >>= 1 ))
(( checksum ^= 0xa001 ))
else
(( checksum >>= 1))
fi
done
done
if (( (data[7] != (checksum & 0x00ff )) || (data[8] != (checksum >> 8)) )); then
echo "checksum Error" >&2
exit 1
fi
if (( data[5] > 127 )); then
printf "Temperature: -%.1f°c\n" $(( ( (data[5] & 0x7f) * 256 + data[6] ) / 10. ))
else
printf "Temperature: %.1f°c\n" $(( ( data[5] * 256 + data[6] ) / 10. ))
fi
printf "Humidity : %.1f%%\n" $(( (data[3] * 256 + data[4]) / 10. ))
exit 0
|
