I use 0Ω resistors to set the I2C address of a slave device. I thought I’d save myself some soldering and jump across some of these footprints with a printed wire to set a “default” address. Of course it’s easy to cut a 0.25 mm trace if I need to change the address.
However, the implementation isn’t working out as expected. If I jump these resistors, the net between R426 and R427 turns into ground, and therefore gets poured. Not helpful! Is there either:
a) a “correct” way to execute my plan of shorting 0-Ω resistors?
b) a way to force KiCad to accept the fact that I want this net to be ADDRESS1, not GND?
You must not shorten 2 nets. Anyway your power supply will complain about this.
Try a copper only footprint like SolderJumper_2_Open possibly with another Closed version or pullup resistor. If you have a wave solder machine, you can close the pads automatically depending from place or soldering direction. Should look like here:
Thank you for your three ideas! Who knew there were so many ways to solve a problem.
In the end, I went with @halachal’s suggestion and added a copper line to a resistor footprint, called it a “JumperR,” and dropped that on my board. It looks great, and the nets now have the correct names! (So exciting.)
Looks good. An idea to make it easier to change addresses in the future, replace half of those jumpers with 10K resistors (either pull-up or pull-down, your choice). That way a change to each address bit is only either a cut or jumper, not both. You also might want to indicate on your schematic what the default (etched in copper) address is. (You may have this already and it just didn’t make your screenshot…)
None of these six resistors will be populated now that three of them are jumpered (effectively populated) in copper. Previously, I had to populate these three resistors manually (six solder points!) Plus, copper is “free.”
@SembazuruCDE, yes I did make a note on the schematic of the “default” copper address. I know I’ll forget what I was doing in a week, so notes are vital! Also, I’m too lazy to look it up right now, but I think the data sheet for this part specified tying the address pins directly to Vcc or GND, which is why I didn’t use pull-ups/downs.
Out of curiosity I did an internet search on SPDT DIP switch, and found that those devices are actually on the market, both THT and SMT. (I’m used to DIP switches all being SPST.) It might not make sense for your current project, but it is nice to know they exist.