first pcb try

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.

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

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

CrossRoads: 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?


Vcc needs to connect ACVV, and connect both to +5V. Put a 0.1uF cap on both pins. Put a 0.1uF cap frpm Aref to Gnd.

Is this what you mean ?

Almost - don’t connect Aref to +5, just a cap to Gnd. It has internal connection to +5, or +3.3, under software control.
Connect pin 7 to 20.
This where a view of the schematic comes in handy.

If you can do a ground pour, or ground fill, or whatever the program you are using calls it, then you can delete the all over the place ground traces and just connect those pins to the ground plane instead. That will make for quieter signals too.

You have room on the board - I would add a diode in parallel with the reset resistor - anode to the reset pin, cathode to +5. This will keep any spikes that occur from making the chip think its going into High Voltage programming mode (and look liket its just hung up to you). 1N4158 type of diode is sufficient.

Looks like you have 2 regulators? Would recommend caps on the 2nd regulator also. 1uF on input, 0.1uF on the output.

Do you have any plans to add pin names (D0, D1, etc) or part names (C1, C2, etc)? That really helps to make the boards look sharp.

I’ve added capacitors to 2nd regulator and added label names for them.
you mind checking? :wink:

Looks pretty good. Trace for pin 20 is kinda thin compared to the rest. Maybe indicates it has not been routed yet? Schematic turned out pretty good. Still recommend a diode across R4 for reasons described before. At least put pads in for it if you don't want to install it to start.

I was kinda afraid of modifying the schematics because first i suck at understanding them… but i think i can understand them by now.
About the thin wire, yes i didnt double click so it was a rastnest line instead of being a wire (corrected now)
diode just like that?

Looks good.

No obvious mistakes ? Like wrong connections or such ?
i’m ready to try my first pcb etch

You mind also take a look at,149447.0.html
it’s related to this pcb i’m making

None that I see. I still recommend a ground pour - that will save on etching material also as you only etch enough to isolate the pads & traces, and not clear out whole big sections of the board.

Is this what you are saying ?
i’ve choose GND as a ground seed and then did Ground Fill
i cant understand how it works and how i’m gonna etch my pcb like this

that doesn’t look good
the ground fill bit has worked
but it seems to have nuked all you lovely traces :frowning:

i really dont know how to do this with fritzing, i think i leave it just like it was before... and maybe in the future use another program like eagle

I would go for Eagle every time takes a few extra minutes to get up to speed, but it's like moving from crayons to calligraphy (IMHO)

apart from anything else - there are so many people here who can help you with it this problem would have been a doddle!

That's the idea, but it seems to have the ground on one side of the board and the traces on the other, hence the 2 different colors (yellow-ish gnd, and reddish traces); from the jumpers you showed earlier I figured you were making a single sided board. Try it again with the ground pour on the same side as the traces. What you want is to just have the copper removed from next to the traces and around the pins, you can see where that took place arond the pads already.

Yes the board is single-sided… i really cant do that ground pour with fritzing.
i’m trying moving the wires to the other side of board and doing copper fill to see if this is what you mean.