I've now hooked up the temperature logger's AVR ISP cables (right above) to program the device, as well as the uart through an FTDI cable to my computer to test and develop the data exchange protocol with the help of some python code. Of course on a working device this will be done with a special connector, but I'm not making one just yet because the pads have changed between the first and the second prototype designs, but I've only built the first prototype. The code won't need to change much, so this setup is fine for coding. I'm also planning to make the firmware user-updatable through the uart by use of a bootloader, so regular users will only ever need one cable. But that's another story...

On the right, above, you'll notice a loose cable almost touching the right-most header. I've done this to simulate the fourth connector, which on my designed second prototype will short pin PD2 to ground, allowing the mcu to detect when the uart cable is connected. And that's also another story.

The connector board, firmware, and computer software will all be open-source and added here in due time. There's a long way ahead!

(Check out the Github for the current firmware state and eagle files)