Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

Cascading CPLDs on different PCBs

I'm designing a basic harness continuity checker based on shift registers implemented in Max V CPLDs. I'm aiming for a modular/extendable PCB design for the project as it has several benefits (cost, ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

Dave,

You mentioned that I should have an external oscillator on the board that feeds the global clock network of the CPLDs via the GCLK pins.

My questions are:

1) Do I need to connect the oscillator to all 4 pins? The development board's schematic shows the oscillator being only connected to one pin.

2) What's the best way to send this clock source to the next PCB? LVDS I presume? I'm gonna go with a oscillator of 8 MHz or so.

3) Is it better to go with an oscillator or a crystal?