All good points. By the way, yes, if you have one peripheral device on an i2c bus, and your design is small enough that you're drawing the device on the same p

All good points. By the way, yes, if you have one peripheral device on an i2c bus, and your design is small enough that you're drawing the device on the same page as your microcontroller, you should make the connection explicit. My two cents: - Making the power routing completely implicit is another hallmark of the style and it drives me crazy too. The power, charging, and maybe FTDI boxes should all be together on one page. Now, I might change my mind about this in six months, but I am starting to warm to the idea of drawing a power tree for even pretty simple power schemes like this one. The power tree style in the Arduino documentation is pretty nice - In the same vein, even modest designs usually benefit from a block diagram up front. You don't need to use hierarchical design functions - just boxes and arrows and text done with the drawing tools of the CAD program - I like that they actually did put most of the "bookkeeping" connections on the left side of the micro. I'd move the UART pins over to that side too, and the programming port. The programming port belongs with the micro and nowhere else, would you put it on its own page? - Audio signals flow right to left to down for no particularly good reason except to get all the other boxes to fit on the second page. All the audio could be on its own page - Similarly, LED signals come in to the rotary encoder on the right and encoder signals come out on the left. Really? - I like that they grouped the bypass capacitors with the ICs but for these modest numbers of bypass caps I prefer to see them shown connected to the pin pairs they'll be placed by - OK, not a schematic point and not critical for a hobbyist product but powering the battery charger from USB is a potential issue. Low line by spec on USB is 4V at the connector, and you won't get 4.2V out of that with a linear charge controller. They might also be exceeding maximum effective capacitance on the USB power bus. Again, not critical for a low-volume "maker" product - it will always work except when it doesn't - No off-page connectors for off-page connections. I like to see the pages called out that an off-page connector connects to, but I admit that's a pain to do by hand - The pull-ups and pull-downs in the top right hand corner of the second page are typical of the style. Who ever heard of connecting these directly to the pin that needs them? Again, it looks like this was done to fit the subcircuit in the box