PCB different then Schematic?


#1

I’m trying to understand where I went wrong in my design. I made a schematic that has a switch connection to a capacitor to ground. Sometimes I want that capacitor to be connected to ground and other times I don’t (hence the switch). It looks like the switch controls the capacitors connection to ground on my schematic but now on my PCB. There is no connection between the switch and the capacitor/ground. I uploaded my files and pictures. Any suggestions appreciated.

Attiny_Program_Board.zip (13.3 KB)

z2z2


#2

This needs an FAQ entry…!

Problem: You have changed the grid size from the default and now the connections don’t connect.
Fix: Move the nodes to a 50mil/1.27mm grid
Solution: Don’t ever change the grid size to less than 50 mil/1.27mm!


#3

You do not have the switch between the cap and ground. The cap is always connected to the gnd pins of your arduino. It seems you want the switch between reset and the cap. Here the comment of @bobc applies. Run ERC and it will tell you that there is not connection on the reset pin. (The green circle/rectangle at the end of the pin should also tell you that there is a problem. Correct connections do not come with such a circle or rectangle.)

Are you sure this is the correct way to use the reset pin?


#4

Ahhh I see it now! :slight_smile: Appreciate the suggestions and advice, will choose larger grid size from now on. Thank you!!!

I bread-boarded the circuit and it works so it should be right. Building this board from a schematic I found online:
z3z3z3z

Originally found schematic here:


#5

It seems weird, but the capacitor is needed to ensure that the “host” Arduino does not reset when a sketch is loaded to the “target” AVR. There is some explanation here https://forum.arduino.cc/index.php?topic=104435.0

However, to program a sketch to the host Arduino the cap must be out of circuit, hence switchable.