Отправлено KA 02 декабря 2003 г. 15:35

Physically Apex20k I/O just has one register. The datasheet just shows three configurations. What this line

"The output enable and input registers are LE registers in the LAB
adjacent to the bidirectional pin."

means is if the user has input, output and oe register and if he wishes to pack all three of them, only output register will be packed into the I/O pad and the other two will be packed into the LE in the LAB adjecent to the BIDIR pin.

If the pin is in the ouput mode, then output flop will be packed, if the pin is in the input mode then input flop will be packed. In the bidir mode only (when all three regs are present), only output reg will be packed into the I/O.

• Кстати, если паковать Input Register, то времянка может ухудшиться по сравнению с использованием ресурсов LE.... — _aquarius_   (02.12.2003 17:56, пустое)