In a previous article, we had use an Arduino + RF433 chip + DS28B20 to come up with a cheap temperature sensor.
We are going to improve the setup by replacing the Arduino Pro mini by an ATTINY85.
See here on how to flash an ATTINY85.
See rf433_sendOOK_at85 for the code.
Note that power consumption will be as low as 0.005ma (5ua) with a peak at 18ma when reading temp.
See below a revised wiring replacing the Arduino by an ATTINY85.
In previous article, I made a cheap temperature probe using an arduino pro mini.
Still, the arduino pro mini is a bit overkill and i would like to keep it for prototyping my projects, not on « live » projects.
So lets have a look at the attiny85 :
-it is cheap (1€ a piece)
-runs at 8mhz
-has 8k programmable memory
-has very low power consumption
Sounds perfect for my needs !
Lets have a look at the pinout.
To flash this baby, I decided to use my arduino uno r3.
See below a quick how to.
1- unzip attiny under Documents\Arduino\hardware (you should end up with a folder attiny in there)
2- start the arduino ide and upload the arduinoisp sketch (in the arduino examples) to your « arduino uno r3 » board
3- choose « arduino as isp » under tools\programmer menu
4- choose « attiny85 (8mhz) » under tools\board
5- upload your sketch onto the attiny85
Lets see how to wire our attiny85 to your arduino.
In a next article, we will see how to adapt this article for attiny85.
Hint : if you are getting the error « relocation truncated to fit », have a look here (and see to replace your ld.exe).
My little project this last week end.
I need to add a few rf433 oregon temperature sensors to be linked to my rfxcom + jeedom domotic box.
Unfortunately, these sensors (oregon THGR122N) are about 25€ (or 15€ using a cresta clone), not including shiping costs.
Therefore I decided to do a cheap one myself using :
-an arduino pro mini (2.50€)
-a fs1000a transmitter (1.50€)
-a ds18b20 (1€)
The whole thing uses less than 2ma when sleeping, and max 20ma when it reads temperature from the ds18b20.
Here comes the sketch rf433_sendOOK.
Note that that I am re using code from connectingstuff.net to send oregon 2.1 compatible packets.
Possible evolution would be to replace the arduino pro mini by an ATTINY85.
Here comes the wiring.
