My project runs 12 LEDs from the Nano (clone). Since there are enough digital pins, I'm not using shift registers (but probably going to use Darlington arrays). For ease of soldering, it would make it beneficial to have one array (16 pin) each side (I'm using stripboard).
If I didn't cut all the strips under the Nano, I could connect, say, pin D2 to the array but it would be on the same track as A7 - the analogue pins are unused in the project so is this likely to cause any problems or should I rethink my board design?
spandit:
However, I see that I can configure them as digital outputs anyway so might as well use them as my project has no need for analog input
Good idea.
CrossRoads pointed out that A7 - and A6 in fact - are not digital pins, but the others are.
Apart from wasting the functionality of pins by paralleling them, the concern is that particularly during program development, you might accidentally set both pins as outputs with conflicting logic levels, causing essentially a short circuit within the MCU and overloading the drivers.
Thinking I might build this with a bare AT chip as I have a few. I'm going to include an RTC module so might run the chip from that rather than using a crystal, although the internal oscillator is probably sufficient.
