Schematic Interpretation

Can anyone tell me which Arduino pins the sm130 Evaluation Shield does not use?

My guess would be A2, A3, 3.3V, AREF, and D7-12

Also, what are the asterisks next to certain pins like D3, D5 and D6?

  • are the PWM pins - D3,5,6,9,10,11 on an Uno

Thank you. Any ideas on that schematic?

Depends on how you have the jumpers (SJ1 through SJ4).

I had no idea there were jumpers to set.

In your defense, there may not be jumpers on the actual board.

But those of us on this side of your monitor are working with the schematic which indicates there are jumpers.

mgiara: My guess would be A2, A3, 3.3V, AREF, and D7-12

And you' be wrong. Only A2 & A3 aren't used. However D7/8/9/10 only go to jumper links so they are optional (alternative RX and TX pins) and D2..D6 go just to a header (JP6). The other signal pin goes to the chip - you need to look at the net labels, not just follow the net wires.

|500x500 Look at the rectangle just above the reset buttons, it has the label UART SELECT. This is where the "jumpers", SJ1 to SJ4 are located.

By default D7, D8, D9 and D10 are already selected, by a blob of solder. You need to use a soldering iron and desoldering braid etc. to change the settings.,

JohnLincoln: |500x500 Look at the rectangle just above the reset buttons, it has the label UART SELECT. This is where the "jumpers", SJ1 to SJ4 are located.

By default D7, D8, D9 and D10 are already selected, by a blob of solder. You need to use a soldering iron and desoldering braid etc. to change the settings.,

Right!! Forgot about those. So if I haven't changed them, which pins are unused?

MarkT: And you' be wrong. Only A2 & A3 aren't used. However D7/8/9/10 only go to jumper links so they are optional (alternative RX and TX pins) and D2..D6 go just to a header (JP6). The other signal pin goes to the chip - you need to look at the net labels, not just follow the net wires.

Thanks MarkT! I've never done anything like this. My guesses were made by a person whose never seen a schematic before which is why I came here! :)

What is a jumper link? What's the JP6 header? What is a net label? How do I know a wire is a net wire?

Thank you MarkT.

A jumper link enables the optional connection of one wire to another.

A header is a place to put a connector or solder wires directly.

A net is a collection of connections that are connected together. A net label describs those connections like 5V power or ground.

All wires belong to a net. All nets are at least connected to two components sometimes more. When a net has no special meaning like it just connects a resistor to an led then the net names are just arbartry letters and numbers.

Thank you Mike!