schematic and code
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Nice, I’d want a little more protection on that clock input though.
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A question, are the 2 GND pin on an arduino need a connection to GND ?
I think about another schem, because he don’t write GND connection on it :
on other arduino project schem i find only the GND pin near Vin connect to GND, the 2 GND pin are connect inside together ?
On the nano, I usually connect just one, the most easy one to connect in that project, and it always worked…
Looking at the schematics, they are connected internally.
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But remember, that’s for a Nano.
If you are using a bare '328, which has also two GND pins, you need to connect both to gnd…
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Think I can get that Nocked up and sent to JLC tomorrow, Try and tag it into the other boards I have in the Pipe Line 
Rob
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what’s bare’328 ? only the chip ?
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Yes. Chip only. Without the board the grounds are not linked.
That said it’s a very forgiving chip for power.
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Check out his insta, this guy is building Kosmo! Is he a poster here?
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I am working on this and have simplified it ( I think )
Using GND rail for the switches and INPUT_PULLUP in the code should allow for all of the resistors to be removed. I hope…
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First thing I thought when I had a look at the schematic !
Just wire the switches on D2 … D13 to GND, and invert the value you read.
Furthermore you do not need to use a 78x05. The arduino nano can be powered using the VIN input which can be used for an unregulated 7 to 12 Volts DC.
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And they connected the 78x05 to VIN, which is incorrect.
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Yeah I used +5 in.
Couple of alterations on the schematic for mechanical interface layer…
PCB all but done
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I’d use a series resistor and a couple Schottkys to the rails (instead of the series diode and resistor to ground) on the clock input:
Yes, the ATMEGA328P has internal protection diodes, but the datasheet nevertheless says maximum input voltage is -0.5 V, Vcc+0.5 V.
Likewise the output pin on the MCP4725 is supposed to be within -0.3 V, Vdd+0.3 V, and output current is max 25 mA, so it should have similar protection. Or buffer with an op amp.
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I will take your advice and update the Input.
I like that approach. It’s elegant and yet belt and braces too. Pinched for my notes. Thank you.
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