I just posted my first project here. I would like to get some feedback on it. Please be gentle :) I'm not exactly sure how to link my project to the forum, but if you search "YABC", you'll find it. Thanks.
[cliff: just try something like:]
Hi there, I guess no comments. :o)
I had a quick look at your design and have the following comments.
Difficult to check the tracking as I don't have Eagle but your VCC and GND tracks look a little on the thin side. You might consider this for any future projects although I see you do have a ground place on the underside to this would help for the GND connection.
Also, you have no decopling on the board. I see you are feeding the board with 5V so using an external power supply. You should still fit local decoupling, and in your case I would suggest at least 47uF to 100uF electrolytic or tantalum on the power input to the board. Put a 0u1F cap in parallel with this.
You also really need 0.1uF caps next to the processor power pins. In most cases you are likely to get away with it but I know from experience of not fitting them that you can get the occasional crash that is unexplained. You have LED displays being switched on and off at high speed using multiplexing and this is going to generate possible transients on the power lines. The reason why you need thicker tracks and decoupling.
I generally add 0.1uF at every power pin on a device. With the Mega32 in PQFP package you need 3. Two for the VCC lines and 1 for the AVCC line.
Nice job though and well done for having a go at doing a real PCB. It gives you a nice satisfaction when it looks professional when completed compared to building on proto board.
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