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[on:]

hi
im learning to lay out a pcb and want to put the atmega328 chip into it, i really just want to be double sure on the pin out of the chip, as ive got it layed out on my board

pin8 +5
pin 9 crystal + cap
pin 10 crystal +cap
pin 20 +5
pin 22 Gnd

pin 21 is this pin i wasnt too sure about is it +5?, i see from some guides connect +5 to it - AREF, what does this pin do?

ok i see its the analog ref pin for max input range 5v.
thank you

[Reply #1 on:]

Did you make a schematic? If you upload it, it will be a lot easier for us to see if it's okay.

[Reply #2 on:]

Nope, that pinout is definitely wrong, pin 8 is GND, pin 7 is +5V

[Reply #3 on:]

I always make sure I've had a look at the datasheet before I commit anything to a PC board.

[Reply #4 on:]

Or use the Sparkfun library if using Eagle?

[Reply #5 on:]

When I use a bare ATmega328 on a breadboard I use this drawing to see the pins:
http://www.hobbytronics.co.uk/arduino-atmega328-pinout
Very handy because it has the Atmel and Arduino pin numbers on it.

[Reply #6 on:]

Or copy an arduino schematic as a starting point, delete the parts you don't need.

http://arduino.cc/en/uploads/Main/Arduino_Uno_Rev3-schematic.pdf

[Reply #7 on:]

thanks very much for the help

[Reply #8 on:]

Or this:



That has the pins, the minimal configuration, and the Arduino pin numbers in brackets.

[Reply #9 on:]

I really like Adafruit's stickers for breadboarded 328s, http://www.adafruit.com/products/554
When I am working on a prototyping board I will cut one in half lengthwise and reverse the sides to mirror the pins and stick them  on the bottom of the board.
Saves reversing everything in my head.
TomJ

[Reply #10 on:]

I think a few corrections are needed:

CTS on the FTDI connector needs to be grounded as well for the FTDI breakout board/cable.
(CP2102 modules don't need the CTS pin.)
Pin6 is DTR.

What's the 10K on the Tx line? That will kill any transmit drive capability.

[Reply #11 on:]

I've posted my eagle library here, which has a physical layout corresponding to the chip.
It might be useful: http://n0m1.com/2012/04/30/how-to-bread-board-arduino/

[Reply #12 on:]

Pin6 is DTR.

I don't know how those ideas got into my head, but I found this once:

http://www.sparkfun.com/datasheets/DevTools/FTDI%20Cable%205V.pdf

That has pin 6 labelled as RTS.

[Reply #13 on:]

What's the 10K on the Tx line? That will kill any transmit drive capability.

Why would it do that?  Its to protect the pins and allow Arduino pin 0 to be used as an output.

[Reply #14 on:]

here is my chip layed out whith what i think should be there could someone please verify it please.
thanks