| XC3000 | XC4000E | XC4000X | XC5200 | XC9000 | Spartan | SpartanXL | Virtex |
|---|---|---|---|---|---|---|---|
| N/A | N/A | N/A | Macro | N/A | N/A | N/A | N/A |
CY_INIT is used to initialize the carry chain in the XC5200 architecture. It is used in conjunction with multiple CY_MUX elements to implement high speed carry-propagate or high speed cascade logic. CY_INIT must be placed in the logic cell (LC) immediately below the least-significant carry element (CY_MUX) in the carry/cascade chain. The INIT input is driven from the direct input (DI) to LC. The CY_INIT carry-out (COUT) drives the C in input of the first LC in the carry chain. The COUT output reflects the state of the DI input. This figure represents the schematic implementation of CY_INIT.
Figure 4.52 CY _INIT 4-Bit Adder Implementation XC5200 |  |
