Here is source code to decode Otio SHT-10 Temperature and Humidity sensor using an arduino and RF433Mhz Receiver
This may work with some other various device clones, but has only been tested on Otio SHT-10 model.
This code is based on following page work :
http://arduino.cc/forum/index.php/topic,142871.msg1106336.html#msg1106336
Byte type is defined by time between 2 rising edges :
Synchro byte : 9320us
1 : 4500us
0 : 2530us
Here are Typical messages sent by sensor (3x36 bytes - 3 times the same message):
11001110 0011 111000001000 01100010 1110 - 11001110 0011 111000001000 01100010 1110 - 110011100011110....
11001110 0011 100000001000 11001010 1111 11001110 0011 100000001000 11001010 1111 11001110001100
11001110 0100 010001110000 01100010 1001 110011100100010001110000011000101001
Here is how 36 Bytes datagram is composed :
| 36-29 | 28-25 | 24-13 | 12-9 | 8-5 | 4-1 | |
|---|---|---|---|---|---|---|
| Header | Infos | T 0.1 °C (LSB) | Humidity (unit) | Humidity (Decade) | CRC | |
| Trame | 11001110 | 0101 | 111001110000 | 1010 | 0010 | 1011 |
| Result | 23.1 | 5 | 4 |
How to get Channel from Header :
| Header | Meaning |
|---|---|
| 11001010 | xxxx10xx --> Channel 2 |
| 11000110 | xxxx01xx --> Channel 1 |
| 11001110 | xxxx11xx --> Channel 3 |
How to get Extra infos :
| Infos (ABCD) | Meaning | Value |
|---|---|---|
| A | Battery state | 0 --> OK 1 --> KO |
| BC | Unknown | |
| D | Sending mode | 1 --> Tx button pushed 0 --> normal mode |
Reverse engineering done with :
- Arduino leonardo
- RF433Mhz Receiver
- PC with sound card and Audacity (Low cost Oscilloscope)
- Male 2 Male Jack 3.5 cable
- 1 wire tight between RF433Mhz Receiver data pin and left/right Jack 3.5 channel
- 1 wire tight between Arduino ground and Jack 3.5 ground
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