KiCad reassigning footprint values. - Page 1
Forum section: electronics / beginners

author: Cy
author_rank: Newbie
timestamp: March 25, 2018, 11:27:49 am
content: Hey there.I'm currently trying to design a PCB forhttp://searle.hostei.com/grant/index.htmlGrant Searle's 6502 computer.I'm stuck at the layout part of the design because Kicad seems to override my pin functions.I've been trying things for days and would appreicate some help figuring out why it keeps going wrong.The Design uses 3x Oscillators but when I get into the footprint layout part of the design.U9 Pin 14, 8 and 7 becomes a 5v input.U10 pin 14 and 7 becomes an 5v input.And same for U11.Can someone explain why these chips are being overriden from my schematic layout?

author: Twoflower
author_rank: Frequent Contributor
timestamp: March 25, 2018, 11:46:02 am
content: Probably you have somewhere a connection between GND and +5V in your schematics. See if other devices (e.g. U1) has the same problem.One additional note: You should think about to clean up your schematics. It's a bad design choice to run traces through the symbols. Also you should reduce the number of edges (e.g. picture 12, trace U9, pin8). It makes things harder to read. and probably help to find mistakes.

author: nali
author_rank: Frequent Contributor
timestamp: March 25, 2018, 12:50:34 pm
content: Try1. Do an ERC check in the schematic, see if there's an error like Twoflower suggests2. Make sure your netlist is up to date: export it from the schematic & import it to the layout3. Have you changed the footprint & re-imported the netlist? You may have 2 footprints for the same component (try deleting the footprint(s) & re-importing the netlist)

author: hermit
author_rank: Frequent Contributor
timestamp: March 25, 2018, 04:00:19 pm
content: Did you modify the part and save your configuration? If so you MUST change the name or move your library to the top of the search list. KiCAD will use the fist instance found.

author: EntropyWizard
author_rank: Contributor
timestamp: March 25, 2018, 06:44:30 pm
content: Something has gone very wrong. It looks like your crystal has become another "unit" on the same schematic symbol as your atmega microcontroller. Notice the sharing of pin 8, also pin 7 of th crystal == pin 7 of the micro hence the connection to +5V. Perhaps you created a new schematic symbol by copying another one and adding to it instead of starting with an entirely new one. The pin numbers for the crystal should be 1 to 4.

author: Twoflower
author_rank: Frequent Contributor
timestamp: March 25, 2018, 07:35:33 pm
content: You should clean up your schematics. Something you've done in the attached picture screams for a problem.And check the datasheet of the oscillators. The open enable pins might cause for trouble as well if there is no pull up resistor build in.

author: bson
author_rank: Unknown
timestamp: March 25, 2018, 09:17:19 pm
content: Don't run wires inside components. The pins extend inside and you're likely to create connections. Run DRC and examine the markers - it should tell you about a short someplace.

author: paulca
author_rank: Super Contributor
timestamp: March 26, 2018, 07:09:20 am
content: On the first schematic PIN4 on the DIN connector looks like the labels are confused and the 5V one might be assigned to the ground connections.+1. Clean it up! You will not be able to spot the problem with that rats nest.First thing I would do is look up creating new components in your own project library. Then make a renamed copy of the ATMega328 component and move the pins from one side to the other so make the schematic clearer.Like this for example:Also... to change the values on the PCB you need to:* Change the schematic.* Export the netlist* Import the netlist to the PCB layout - switch on "Allow change footprints" if you changed any.Labelled connections do not need to connect. If you put a +5V on a point in the circuit, it will automagically be connected to any other point labelled +5V when you come to do the PCB.