Optional Pullup (simple)

[AtomSoft]

Ok im trying to save space on a PCB and also save on parts by making a few pullups OPTIONAL.. The question i have is... instead of me having a JUMPER on each line... can i just have them all connect to one VCC2 and a jumper to VCC1 connect them both...

Basically will having partially connect resistors pose a issue? I doubt they will but dont want to take the chance.

Thanks

 

[MikeMl]

Are you describing having multiple port pin pullups tied to the ports, but leaving the Vcc end (common to several pullups) floating? If so, that might not be a good idea...

 

[AtomSoft]

Yeah, i just understood why right now

The other pin can pull one high when not needed... I removed that idea from the board and just omitted the pull-ups entirely

 

[Nigel Goodwin]

Yeah, i just understood why right now

The other pin can pull one high when not needed... I removed that idea from the board and just omitted the pull-ups entirely

If you were to do it that way the answer would be to ground the other end - so selectable as either pull-ups or pull-downs.

 

[AtomSoft]

Hey Nigel, yeah i planned to use a solder jumper, but i simply took them out since it is for a i2c bus and i only need one pair anyway which i plan to have on the main pcb. Its ok tho... Thanks

 

[KeepItSimpleStupid]

Will a SIP network help? or Two SIP networks? One for the pull-up and one for the pull-down. Snip the pin your not using.