Atmega16 breakout board

I’ve really got to get back into writing up some projects, many PCBs made, but very little to show for documentation on them. This one’s rather simple. I had a pile of Atmega16 chips and nothing to do with them. I could have hand-wired them each into individual projects, each with specific crystals chosen for their application and programmed each one out of circuit. That would have been cheaper, but in reality it means I would never get around to using them at all. I needed something to make them easy to use and prototype with, maybe do up a custom board for a final application, maybe just solder in the breakout board and be done with it.

This is what I came up with. That is a thinly veiled euphemism for ‘completely ripped off the design’ but I did make some key changes to make my life easier. The original design comes from MightyCore, a port of arduino to these atmega processors. They have a bunch of documentation, most of it applies here. I customized this layout in a number of ways though:

  • The pot changed to a multi-turn
  • the large capacitors became electrolytic (I had those as salvage)
  • silkscreen simplified for this one processor
  • headers got more detailed labels
  • changed LED buffer to something I had
  • moved usb uart offboard
  • optional power from ftdi
  • split off avcc

The strange NLV17SZ17DFT2G buffer I’m using for the LED is to not load down that pin, it almost assuredly doesn’t matter but I had the parts from an electronics goldmine order so I used them. I also include a solder jumper if those parts are not available.

My intention for the potentiometer is to have the ability to set the AREF if needed, similarly the ability to run the AVCC from a different voltage is available (but I don’t honestly expect anyone will need that very often).

I have had issues in the past where a board draws too much power from usb and causes issues, that’s why I have the ability to split the power from the ftdi connector and leave that only for communication. Tou will have to either feed the 3.3 or 5 volt rails directly in that case or power it with a barrel jack (the original labels this vin, I’m realistic and know it’s gonna be used with 12v).

These boards can be programmed with a regular ISP, there’s JTAG available as well, but if you want to do things easily then use the mightycore bootloader and program them with the arduino IDE. They have a bunch of IO pins and 5v level logic so there’s a bunch of things they’re still good for. My board designs are available on github, or you can e-mail me and ask for one (I have more than I need).


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