Here’s the first EagleCAD revision of my Moteino project.
You can find the files on my GitHub repository, along with other projects that I am/will be working on.
Here are a few design considerations:
- I decided to use the MCP1702 3.3v regulator instead of the MCP1700 I started with. There’s no significant difference and allows the Moteino to be powered from a 9V battery (up to ~13V actually)
- the onboard LED is not on the traditional D13 line, because that line is used by some SPI devices that pull it up. Consequently the LED would blink (and use some power) whenever talking to SPI devices so I decided to put it on D9 which is a PWM pin. Also it sits on the edge of the board so it’s visible even when you stack something on top
- I enlarged the board slightly to allow the RFM12B radio to fit easily underneath when soldering male pins on the bottom. My very first batch was 0.1″ narrower but I had a hard time fitting the radio with male headers next to it. This makes the board slightly wider but easier to use with any kind of headers, above or below
- I built my own version of the RFM12B footprint featuring only the necessary (also shorter) pads
- The board could be shorter overall at the expense of fewer broken out pins. I decided to keep all the ATMega pins available. The standard Arduino actually does not include A6 and A7!
As always, feedback and suggestions are welcome.