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Have you tried performing a timing analysis using Quartus? The MAX3000 devices are simple devices, so they are unlikely to be flexible with which pins can be used without Quartus giving warnings. For example, create a design containing multiple instances of counters with clock and reset inputs, and perhaps route all carry-outs to pins. Assign the clock and reset to global pins, synthesize the design, and look at the timing. Then change the clock or reset to a non-global pin and see how the timing changes. To get a better feeling for how the timing changes, try and fill the device with counters, and try changing the counter widths.
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Thank You, it's interesting, I'll try.
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To answer your specific questions; clock and reset should use global input pins (these are usually listed in the pin files for the devices and in the Quartus pin planner GUI). Your tri-state outputs can be controlled however you see fit, eg., by logic within the MAX3000 or an external control signal. Its unlikely that OE needs to use a global input, but there is no harm in using one either. You do not need to use OE at all if the signal from the MAX3000 is an output-only, i.e., only routes to the inputs of external devices.
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It seems, in real project "output-only" outputs to be required, but a 16-lines bus variant with tri-state was concerned too.
So as EPM3032 has two global pins OE1 and OE2/GCLK2, I want to understand, how it should be used to organize 16 tri-state outputs
- should I place 16 tri-state primitives and control them with global OE drawing corresponding lines to each primitive in Schematic
or
- I should change some settings and don't place tri-state primitives on Schematic?
Best regards,
Vadim
Honored Contributor
