Oct 182014

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.



 Posted by at 17 h 42 min
Oct 182014

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).

 Posted by at 13 h 46 min
Oct 062014

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.


 Posted by at 22 h 21 min