m00dawg Posted December 23, 2011 Report Share Posted December 23, 2011 (edited) I read on uCApps that the pull-up resistors on the serial lines (R33-R36) are for if an IC is not plugged into a socket. I'm using SMD SRs directly on my control surface boards such that I really only need a pull-up on the serial line for the last SR on the board before it goes to the next set of pin headers, correct? So basically: J9 In Header -> SR -> ... -> SR ->---+---> J9 Out Header | Resistor | +5V Hopefully that makes sense :) Basically the resistor is before the J9-Out in case there is not another board (and thus another set of SRs) connected to that header. Edited December 23, 2011 by m00dawg Quote Link to comment Share on other sites More sharing options...
TK. Posted December 23, 2011 Report Share Posted December 23, 2011 yes, thats allowed Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
m00dawg Posted December 23, 2011 Author Report Share Posted December 23, 2011 Awesome, thanks TK! Glad to know my assumption was correct. Quote Link to comment Share on other sites More sharing options...
nILS Posted December 23, 2011 Report Share Posted December 23, 2011 I'd still suggest putting it on ther, because you never know it you're gonna extend it some day. Quoting SmashTV: "Funny, how a two cent part's got you chasing your tail now, right? ;)" Quote Link to comment Share on other sites More sharing options...
m00dawg Posted December 23, 2011 Author Report Share Posted December 23, 2011 I was always going to have it for my output headers. All the stuff on each control surface module will always be populated (wouldn't make sense not to). But, for instance, my last control surface part in my chain (the ENV/OSC section) still has output headers if I wanted to add another module in the chain. So the question was if I needed resistors for the SRs on the same control surface board. Sounds like it's a no. On the other hand, I already have them laid out and routed on all my boards so it can't hurt to keep them there I don't think. Not having them would give me more room for my ground and power planes though. Quote Link to comment Share on other sites More sharing options...
TK. Posted December 23, 2011 Report Share Posted December 23, 2011 We have to differ between a SMD, and a through-hole based solution (especially if IC sockets are used). It's unlikely that the PCB can still be used if the SMD chips will ever be desoldered. ;) Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
m00dawg Posted December 23, 2011 Author Report Share Posted December 23, 2011 Yup, but the orientation of the modules could differ. Hence, I should always err on the side of caution and have a pull-up before my out-pins is what the consensus sounds like (or, if in doubt, just put in pull-ups as per the standard DINx4 design :) ) Quote Link to comment Share on other sites More sharing options...
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