Help understanding simple Arduino>USB schematic

Forum 2005-2010 (read only) Hardware Interfacing
1

Hello,

I am new to Arduino in general. Never really worked with any sort of real microcontroller. I usually just stayed with the simple projects that were easy and I could get up and running in a couple of minutes.

I decided to change that and I am going all out, building my own Arduino board. I have a very basic schematic for the Arduino. It's pretty barebones and not nearly as versatile as the production PCBs but its functional.

I was going to use a MAX232 and just have a serial out but I thought that would be pretty lame in the age of USB, although serial is still acceptable.

This schematic is directly off the Arduino Nano. I just need a couple pointers so I don't wire anything up wrong and poof, there she goes.

So here it is:

694×500 52.8 KB

Thank you.

2

The +5V are going to wherever your +5V power source is in the system.

The X-ed out pins are not used: correct. The USB port is for data I/O: correct.

The C8 and C9 devices are capacitors that are there to smooth out the VUSB voltage coming from the USB port. They should connect close to pins 5 and 1 of J3, your USB port.

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3

RuggedCircuits, you have been very helpful in my endevours. Thank you. Still figuring out how to read complex schematics. :slight_smile:

Thanks.

4

One more question, would I still have to convert the ATMega signal to real Serial via Max232, or will that circuit do the equivalent and then turn it into USB?

Thanks.

5

You do not need a MAX232. The TXD and RXD pins from the FT232RL (pins 1 and 5) can connect directly to the ATmega. Just remember to connect TXD from the FT232RL to RXD of the ATmega (i.e., cross over TX and RX).

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6

Excellent. Thank you.