I created a simple schema on kicad (this one )
,then associate the corresponding footprint, generate the netlist file,then run pcbnew to create the PCB.But then i end up with this mess here pcb i don’t know how to deal with it ( i did draw the edge of the PCB ). I am trying to draw a PCB i can build myself with no crazy tool ( so i guess single layer),but on this draw many line intersect with other line so not really what i was looking for a single layer pcb. Not sure it help but all my kicad file are there
Where should i start to arrange correctly my pcb ?
Thank for all your insight
Single-layer PCB is an artform.
The ‘simple’ way is to iteratively add jumper links or 0R resistors to create bridges. Then, when 100% connectivity is achieved, you try to remove as many of them as possible.
An easier method is to go double-sided, but use 1 layer solely for GND. If you are making your own PCBs, the through vias/holes will not be plated, so a piece of wire will need to be soldered on each side.
Commercial double-sided PCBs are not particularly expensive and will be much easier to lay out and to assemble.
This ‘mess’ is called a ratsnest.
As long as you don’t have tracks (in pcbnew the wires are called tracks) they tell you which pins/pads need to be connected to which other pin/pad.
Please check this out: https://kicad.org/help/documentation/ (go to pcbnew section, should have step-by-step instructions how to get to a layout.
Thanks you very much for your answer,I am trying to learn so i got on pcb i got on a prototype board ( was a hell ) and now i am trying to a clean pcb for my project.So i have no idea if it’s achievable by myself ( which i love to do ) or if i should order online (but no idea where and how design the whole thing correctly)
First. Back to your schematic and perform ERC. You’ll be very surprised how many errors you’ve got.
When schematic issues be repaired back to the CvPcb and assign correct footprints for C2 and IC1. Especially IC1 which has not standard DIP28 (W15.24mm) but DIP28 Narrow Body (W7.62mm).
Then back to PCB, update netlist, update footprints and start alignment of all components. Stick to the strategy to keep as little crossed ratsnest lines. And finally start laying your tracks.
Thanks,how can i find another footprint for the Atmega328 ?All i can find is lib file and not mob file which to me include the footprint file ( or do i confuse something ?)
You have to have a symbol for the ATmega328 (is contained in a .lib file) for EEschema.
This one needs correct pin numbering/naming to fit a particular footprint in PCBnew.
Page 3 in the 10/2014 datasheet for the ATmega328P mentions 4 different housings (footprints):
Decide for one and then check out the symbol, if it matches the pin configuration in the datasheet.
If you’re lucky there will be one and you can use it, if not you have to modify another one or make one from scratch.
But hey look, you’re lucky, someone already did the legwork for you (essentially all versions are available):
Check the pin configuration of what you get from the library with the one in the datasheet to make sure the board that will be made for it is correct, otherwise you will slug yourself for your negligence.
Then you can use any footprint that resembles the one, that is specified in the datasheet for the ATmega328 that you want to use… in this datasheet this is located somewhere at the end under ‘Packaging Information’. Let’s say you decided to take the DIP28 housing, then this will be what you need as a footprint according to the datasheet:
Again, check exactly how the footprint in the datasheet is specified and then search one in the available repositories (.pretty folder / .kicad_mod files are footprints) via the footprint browser.
… and from here on you’re on your own, cause I don’t have the repos loaded - I do symbols and footprints myself (*) - and I don’t have a SOIC with 28 pins to show you (I use the ATmega328P in the 32 TQFP/32 MLF housing).
Sometimes the datasheet contain the footprints as well, this makes life even easier as you can directly compare with what you need in KiCAD.
*) sometimes there are errors in the symbols/footprints, so be safe and not sorry and check them before you use them! They don’t come with any warranty what-so-ever.
As I wrote before lets start by drawing the correct schematic. If it will not be correct then further work on the PCB will be a waste of time. The schematic may look this way:
The IC2 is the level shifter. If you want to use RF modules powered by 3.3V and microcontroller powered by 5V, it will be needed. MFRC522 is not 5V tolerant. Level shifter wouldn’t be necessary if microcontroller will be powered from 3.3V rail too. Think of it.
BTW. The footprint of DIP28 Narrow Body you can find in Housings_DIP.pretty (standard KiCad footprint library) as DIP-28_W7.62mm.
Atmel library in its current state was made by me.
