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| XC3000 | XC4000E | XC4000X | XC5200 | XC9000 | Spartan | SpartanXL | Spartan2 | Virtex |
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| N/A | N/A | N/A | Macro | N/A | N/A | N/A | Macro | Macro |
DECODE32 and DECODE64 are 32- and 64-bit active-low decoders. In XC5200, decoders are implemented by cascading CY_MUX elements driven by lookup tables (LUTs). When one or more of the inputs are Low, the output is Low. When all the inputs are High, the output is High. You can decode patterns by adding inverters to inputs. Pull-ups cannot be used on XC5200 longlines.
In Virtex and Spartan2, decoders are implemented using combinations of LUTs and MUXCYs.
Refer to the “DECODE4, 8, 16” section for a representative schematic.
| Inputs | Outputs | |||
|---|---|---|---|---|
| A0 | A1 | … | Az | O |
| 1 | 1 | 1 | 1 | 1 |
| 0 | X | X | X | 0 |
| X | 0 | X | X | 0 |
| X | X | X | 0 | 0 |
| z = 31 for DECODE32; z = 63 for DECODE64 | ||||