Arduino Forum

Development => Other Hardware Development => Topic started by: bamboosam on Mar 27, 2012, 02:28 am

Title: Can you guys critique my first Eagle Layout?
Post by: bamboosam on Mar 27, 2012, 02:28 am
This is my first Eagle layout so all the help is much appreciated.

This is designed to control an led strip "mosi & sck", programming it via MKii / AVR Studio 5 and powered by 4 rechargeable batteries so I didn't think a regulator is needed. I placed text on the pins for definitions, I know not to keep them there.
Title: Re: Can you guys critique my first Eagle Layout?
Post by: CrossRoads on Mar 27, 2012, 03:12 am
Add a polygon to each layer (Draw:Polygon) and Name it GND. Get rid of the ground traces.

I would add 0.1uF cap to VCC pins on all 4 sides of the chip, similar to how you have 1 one for Aref.

Your pin arrangement for ICSP is odd - you will have to make an adapter cable to mate to the 2x3 header on the Mkii.
The Mkii does not power the board but needs to receive the Vcc so it knows what the voltage being used.
Thus you need to bring power & gnd into the board while the Mkii is plugged in.

I don't know that the Mkii will reset the uC correctly thru a cap like that. I would connect RST direct to pin 4. The other side of the cap is normally DTR.
If you are not downloading sketches via Rx/Tx you don't need the DTR cap.

'644 seems like overkill for the application, do you need it for the memory size?
Title: Re: Can you guys critique my first Eagle Layout?
Post by: bamboosam on Mar 27, 2012, 03:29 am
It is for the 1284p, and yes I need it for the memory size.
I will be making an adapter for the odd pin arrangement.

Ok I wont be using rx/tx to program it so I will rid the cap, should I still keep the 10K on reset?
Title: Re: Can you guys critique my first Eagle Layout?
Post by: bamboosam on Mar 27, 2012, 03:38 am
I think Atmel recommends it
Title: Re: Can you guys critique my first Eagle Layout?
Post by: CrossRoads on Mar 27, 2012, 03:49 am
10K pullup, yes for sure.
Title: Re: Can you guys critique my first Eagle Layout?
Post by: bamboosam on Mar 27, 2012, 04:11 am
Great. Ill revise it and post an updated version tomorrow.

Oh... Should I add a plane for VCC?
Title: Re: Can you guys critique my first Eagle Layout?
Post by: CrossRoads on Mar 27, 2012, 05:07 am
No.
Gnd & Gnd.
Wide traces for Vcc.
Title: Re: Can you guys critique my first Eagle Layout?
Post by: CrossRoads on Mar 28, 2012, 06:39 am
Yeah, have noticed that sometimes you need to add a manual trace. Could be the ground plane squeezed around the hole is too thin.
Try moving the resonator to the right some.

You can also try adding a via near there, name it GND also, to connect the top & bottom planes.
Title: Re: Can you guys critique my first Eagle Layout?
Post by: bamboosam on Mar 28, 2012, 02:12 pm
Yup, the resonator was too close to the hole.
Title: Re: Can you guys critique my first Eagle Layout?
Post by: bamboosam on Mar 30, 2012, 04:58 am
OK, finished laying out everything I need. Hopefully everything will work.   ]:D
Title: Re: Can you guys critique my first Eagle Layout?
Post by: bamboosam on Mar 31, 2012, 07:03 pm
It was suggested that I make sure spacing between adjacent copper structures be at least .008". I am not sure as to where to define this in Eagle.
Title: Re: Can you guys critique my first Eagle Layout?
Post by: CrossRoads on Mar 31, 2012, 11:13 pm
Tools:DRC, clearance
I use the iteadstudio DRU file for checking stuff.
Put these in the Eagle/dru and eagle/cam folders.

Then select
Tools:DRC:Load, click itead_rule.dru, go from there.

Your choice of board house may have their own files for checking the layout.
Title: Re: Can you guys critique my first Eagle Layout?
Post by: a.d on Apr 01, 2012, 01:54 pm
I would perhaps suggest putting a small radius on the corners of the board - I have found that 90 degs can be quite pointy!
Title: Re: Can you guys critique my first Eagle Layout?
Post by: bamboosam on May 03, 2012, 11:15 pm
I used the drag technique. It worked out very well! :D
Title: Re: Can you guys critique my first Eagle Layout?
Post by: bamboosam on May 08, 2012, 01:25 am
Works great! Thank you guys for the advice, much appreciated.  XD