This is another version of the Alti Duo that is using an Attiny 84 processor. It is smaller than the other AltiDuo that is using an ATMega 328. However unlike the big AltiDuo it cannot connect to the USB port so to program it you have to remove the ship.
As you can see below the ATtiny 84 is a lot smaller than the ATMega 328
It has also only 8k of memory so the programs you are running must be simple.
The altimeter schema
The first prototype can be seen here
The altimeter board
It is quite small, only 78mm x 23mm
Only 18.3grams and remember this is a kit using classic componants
27/06/2013: I am now using smaller transistors.
They are less powerfull only 17A; a lot more expensive but if you look at the altimeter it is a lot lighter, we are now under 16grams which is I think pretty good for a dual altimeter kit.
If you cannot do the board yourself or you want a full kit, just contact me I have plenty of them!!!!!
You will be able to download the full documentation here.
You will be able download the kit instruction here.
The code is being improved all the time and I suggest you upgrade your altimeter firmware each time a stable version is released.
You can download the code on the download page; instructions to upgrade the firmware are also available on that page.