PCB design advise needed

dl324

Joined Mar 30, 2015
16,911
I assume the 2 missing IOs you refer to are the cec_line and cec_gnd they ae the 2 marked vias as right not they are gonna be wires in the board that goto the 2 wires on the hdmi port.
CEC_Gnd has a via and goes to a pin. VDD3.3V doesn't have a via or go to a pin.
upload_2016-6-5_15-47-45.png
 

Thread Starter

yonubear

Joined Jan 10, 2013
73
ok here is what I came up with to remove all but the vias for the cec wires. if this looks electricly sound I will use this for the first board then work on rearranging it for the next 2 I need.
Untitled Sketch new 2.jpg
Thanks,
Yonu
 

Thread Starter

yonubear

Joined Jan 10, 2013
73
wow guess I need to keep practicing with it. I wish there was a 3.3v pin on that side of the arduino though would make it easier

on a side note anyone have any experience using a laser cutter to etch boards I may have use of one and figure I would give it a shot instead of the toner method.

Thanks,
Yonu
 

dl324

Joined Mar 30, 2015
16,911
I wish there was a 3.3v pin on that side of the arduino though would make it easier
Post the footprint labeling all 6 signals on your schematic and I'll give placement another try.

Also indicate which unused pads, if any, can be removed so that area can be used for routing.

Routing traces between pads can be problematic for toner transfer. I usually try to avoid them, but I have done some boards with EPROMs that required routing between pins address and data lines between pins.
on a side note anyone have any experience using a laser cutter to etch boards I may have use of one and figure I would give it a shot instead of the toner method
Are you talking about using a laser to remove copper; or to remove etch resist?
 

Thread Starter

yonubear

Joined Jan 10, 2013
73
ok here is a marked one the cec vias are circled in blue i suppose all the unused points could be re purposed however they match upto pins on the arduino this will be plugged into

ok on the laser it is only a 500mw that the manual says won't engrave metal so if I understand the process I would have to use etch resist method
Untitled Sketch new 2.jpg
thanks,
yonu
 

dl324

Joined Mar 30, 2015
16,911
Here's rev 4. There are vias for CEC_Line (via on right side near 5th pin from bottom) and CEC_Gnd (via close to the top right side pin); the latter is also connected to the ground pin on the board.
upload_2016-6-5_22-0-32.pngupload_2016-6-5_21-52-41.png

I removed the enlarged resistor pads I normally use to make routing easier. I'll consider upsizing in areas that won't be too difficult to transfer/etch.

Might be able to do further optimizations. I was pleased when the ratsnest showed no crossing routes so I quickly routed manually. There was only one place where I needed to route between minimum spaced pads.
 

dl324

Joined Mar 30, 2015
16,911
Final version. I swapped R4 and R10 to simplify routing (eliminated the only case where a trace was routed between min spaced pads), moved C2 up a grid, and enlarged pads.
Before and after:
upload_2016-6-6_9-50-52.pngupload_2016-6-6_9-48-25.png
Only the route from R11 to the base of Q2 gives me any concern.
 

dl324

Joined Mar 30, 2015
16,911
if this looks electricly sound I will use this for the first board then work on rearranging it for the next 2 I need.
You should enter your schematic into your layout tool. I checked connectivity of the bottom half dozen components and found issues that your layout program would flag.
upload_2016-6-6_12-18-5.png
 

dl324

Joined Mar 30, 2015
16,911
What program are you using? I can't seem to get a layout that works
I use the free version of Eagle. Some/many say it's difficult to use; I don't find that to be the case. It's the third free schematic/PCB program I tried. I found it to be better than the first two and sufficient for my needs, so I stopped looking and took the time to become proficient with it.

It's craftsmanship, not the tool, that makes the difference.
 

dl324

Joined Mar 30, 2015
16,911
hey I think I got it
You could make the routing look more professional if you used multiples of 45 degrees for the angles.

Did you come up with the component placement on your own, or did you copy from my 4th revision? Are you using 1/8 watt resistors, or are you planning to bend the leads on 1/4W closer to the body than is normally done?

You mentioned earlier that area for the unused pads on the right/left couldn't be used for routing because they were connected to the Arduino. That wouldn't be the case if you didn't mount the corresponding connector on your board.
 

Thread Starter

yonubear

Joined Jan 10, 2013
73
I am using 1/8w resistors the layout I started from scratch but got fed up so I started matching them to your layout. I will probably remove the unused pads I had inteded to leave them incase I decided to add anything later but I will wory about that later so I am going to omit them.

Yonu
 
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