My temperature or temperature/humidity sensor by mazkagaz

Last crawled date: 3 years ago

My needs :
1/ I wanted to make temperature and temperature/humidity sensors based on oregon protocol to have a full compatibility with my RFXcom.
2/ I wanted it to have a low consuption.
3/ I wanted to choose either temperature only or temperature and humidity sensor.
4/ I wanted to use simple and cheap elements : less than 5€ each sensor.
5/ I wanted to put all this in a box i could fix on a wall, inside or outside.
This is all done.
About electronic part :
attyni85 (low consuption),
DS18B20 (temperature sensor), DHT22 (temperature and humidity sensor),
simple chineese low cost 433MHz emetter,
3 AAA batteries cheap support (i did not have a printer when i started this project..., one can make its own),
put a 10uF capacitor between +5v and ground,
emetter data pin on attyni85 pin 2,
for a DS18B20 : VDD on attyni85 pin 3 and DQ on attyni85 pin 4, and 4.7k resistor between VDD and DQ,
for a DHT22 : VDD on attyni85 pin 3 and DATA on attyni85 pin 4 (simply the same as DS18B20), and a 10k resistor between VDD and DATA.
don't forget to put an antenna on the emetter (16.5cm wire is a good choice).
About firmware part :
I use arduino IDE because it is so simple... My attyni85 are programmed with internal 8MHz clock. I let you seach on your favorite web search engine how to do this.
If one wants to use DS18B20, uncomment "#define SENSOR_TYPE_DS18B20" and comment "#define SENSOR_TYPE_DHT22" and vice versa...
Each sensor must have its own "MY_ID", change the line "#define MY_ID 0x06" for each new sensor. Comments give exemples (used in my house).
NB_CYCLES_DODO is used to tune the time between two mesuse. 20 for about 2'30", and proportionality is your friend... The more you send datas, the less your battery goes on. I wanted one mesure each 5 minutes, but i have big heavy walls, so i send the double to "ensure" i'll get one each 5 minutes.
VCC_BATTERY_LIMIT, in mV, tells you when it is time to change batteries. Be aware you have between two weeks and a mounth when it happens (sensor in yellow on domoticz) until it reaches 3.3v and starts sending mad datas (-127°C for example).
Improvements :
Since two years, I only changed the battery once on DS18B20. For DHT22, i still have to tune the code, it's about 3 mounth the battery set.
Newly, i made the boxes, so it was time to share. I use 3.5mmx16mm INOX (remember the box is designed to be used inside or outside) screw. But all is upside down inside the box, under the batteries, it really can be improved.
I was asked to share it with a technology teacher who thought he could use this in his classroom, so i share with the classroom 3D, unless it is not all about 3D...