Connecting two SXs together

Jim Fouch

I have a project that I will be using 2 - 3 SXs together. My questions is if I us an output from one SX to control the input of another, do I need to pull that·pin low or high, or will SXs keep the lines from floating?

I know on a switch you never really want a pin floating so you pull it low or high w/ a resister (10K??). But I have never connected two uc together like this.

Also, in my design each SX will have it's own 7805. All will have a common ground. Is there any problem with this?

Thanks,

Jim fouch

Chris Savage

Jim,

·· In the case of the SX Chips sharing ground but each having their own regulator, not a problem. As for the I/O lines.· As long as the I/O lines from one are outputs, and they are connected to input lines on another, you won't need pull-up/down resistors, as the lines that are output from the driving device will hold those lines high or low as needed.· Now if it's bi-directional, you may want to implement something.

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Chris Savage
Parallax Tech Support
csavage@parallax.com