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Topic: first pcb try (Read 9978 times) previous topic - next topic

Carlcox89

I'm trying changing it to single side now :)
question: what's the package for 1uF capacitor (options are from 100mil to 300mil THT electrolytic)
also for 22pf capacitor (options are 100mil and 200mil)

Also, i didnt understood exactly what you mean by labeling net as ground... (my native language is portuguese, so maybe that's the problem of understanding specifical/technical english words)

SirNickity

Package sizes depend on the packages you choose.  I have 100nF caps in both 0.1 and 0.2" lead spacing, for example.  You have to check the datasheet for the part you intend to stuff the board with.

If I had to guess, I would pick 100mil for the 22pF and 1uF electrolytic, since that's about what mine are.  You can always bend the leads if necessary, although that's more difficult for electrolytics due to the typical form factor of the part.

CrossRoads

"If you label that net as ground and do a copper pour it will fix the issue."
Assuming one knows how to do a ground pour in fritzing.   The pin and the caps do not look connected on the board drawing presented earlier.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Carlcox89

Ok, so i tried (hard) lol this is the result.
would you mind checking if everything's ok ?

CrossRoads

Where are the 0.1uF caps on the VCC and AVCC pins?
Figure out how make a ground plane, ground pour, whatevet fritzing calls it. Top & Bottom layer.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Carlcox89

#35
Jan 24, 2013, 04:21 am Last Edit: Jan 24, 2013, 06:11 am by Carlcox89 Reason: 1
Oops, forgot to put those.
Ok, i'm going to do a little research on that.

Carlcox89

Ok, now it's where i start to freak out LOL
I already connected the crystal load capacitors ground directly to arduino gnd instead of going through the switch.
I added decoupling capacitors, is it like that?  :smiley-roll-sweat: (attached image)

About ground plane/pour, i couldnt find anything that would make me understand what i need to do.

(i've attached fritzing project just in case someone has it installed and is willing to show me how it can be done)
thanks

Docedison

#37
Jan 24, 2013, 09:33 am Last Edit: Jan 24, 2013, 09:36 am by Docedison Reason: 1
A "Net" is a set of interconnected points like ground. Nets get names from 2 primary places one is the symbols connected. For example a ground symbol is enough to create a net called 'ground'. The second source is the pin numbers assigned to an IC or other part.In the example I pointed out the error was in not editing the net created by interconnecting those 4 symbols, 2 caps a crystal and a processor.
Finally there will from time to time be net names you will create or modify to fix/add/modify circuit connectivity (the netlist).

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

pwillard

#38
Jan 24, 2013, 05:22 pm Last Edit: Jan 24, 2013, 05:35 pm by pwillard Reason: 1
Ok, I took a few minutes and did the most painful think I can think of... I used Fritzing.  OK, My opinion of this tool is 1) it fills a need   2) It doesn't do a great job of filling that need  3) it needs to get beyond what I consider DUPLO block stage.   It lets you do bad things.  Ok, lets just say... I am not a fanatic about Fritzing and leave it there...

Step 1, I tried to make sense of you schematic... and realized it was unfinished.  Anyway... I will post what I did to see what it should have looked like.  Schematics are not always about "showing ALL wires" even though that is what you might think.  Using the convenient GND "net" and +5V "net" can greatly simplify a schematic... see my example.   Your drawing, sadly, showed signs of thing being moved and creating "crazy wires".  (Note: Fritzing file still has an error in Schematic... see if you can find and fix it.)

Step 2, I cleaned up your PCB.  Here's some tips... always try a few routing paths not just the first one you see... your first pass might not be ideal. be prepared to "rip up" work.  When doing single sided boards... always strive to keep jumpers to a minimum.

Also note: My "fixes" are not the BEST I can do... I only have so much time on my lunch hour.  I just wanted to show a cleaner PCB layout.  Notice that I use more of the board.  If you are going to have that much "real estate", no sense making all kinds of bendy wires...


SirNickity

Nice rework.  I'm 100% sure all my remaining complaints are directed toward the tool, not the designer.  ;-)

OP:  Do yourself a huge favor and give some dedicated PCB design packages a shot.  There are a few common ones that get mentioned around here.  Eagle being the most popular, but possibly most complicated, of the free(-ish) ones.  Fritzing is a nice tool to graphically depict a design you have on a real-world breadboard for others to look at, but IMO, not much beyond that.

CrossRoads

Nice job pwillard. That's way more than I am willing to do with that toy.

Carlcox89, are you planning to use the Analog pins? If so, you should disconnect pins 20 & 21, and connect 20 to a capacitor to Gnd.
The connection to 5V will be made internally if used, or you could use the internal 1.1V reference.
If the pin is hardwired to +5, you lose that option.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Carlcox89

Many thanks pwillard for taking your hours ;)
It'll really help me understand what i did right and wrong.

@CrossRoads , i dont intend to use analog pins now, but maybe i need to use them in the future.
So i would have to break the 20&21 pins connection, and connect a capacitor (how much uf ?) to pin 20 (AVCC) to ground ?
thanks

CrossRoads

Yes on Aref. 0.1uF to Gnd, no other connection.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Carlcox89


Yes on Aref. 0.1uF to Gnd, no other connection.

Aref ?
you said "connect 20 to a capacitor to Gnd."
pin 20 is AVCC :o
AREF is 21
So which one should i connect with a capacitor to GND?


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