Там, конечно, 350 страниц, просто непосильный объём. Но ведь интересует конкретное место.
Цитата("Cyclone III Device Handbook @ Volume 1")
Configuration Process
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Reset
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The user I/O pins and dual-purpose I/O pins have weak pull-up resistors that are always enabled (after POR) before and during configuration.
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User mode
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When initialization is complete, the INIT_DONE pin is released and pulled high. This low-to-high transition signals that the device has entered user mode. In user mode, the user I/O pins function as assigned in your design and no longer have weak pull-up resistors