Control-signal transition (assertion and deassertion) setup and hold values with respect to the GPMC output clock edge can be controlled in the following ways:
- For the GPMC output clock signal, the
GPMC_CONFIG1_i[26-25] CLKACTIVATIONTIME bit field (where i = 0 to 3) allows
setup and hold control of control-signal assertion time.
- The use of a divided GPMC output clock allows setup and hold control of the control-signal assertion and deassertion times.
- When the GPMC output clock runs at the GPMC_FCLK frequency so that GPMC output clock edge and control-signal transitions refer to the same GPMC_FCLK edge, the control-signal transitions can be delayed by a half-GPMC_FCLK period to provide minimum setup and hold times. This half-GPMC_FCLK delay is enabled with the CSEXTRADELAY, ADVEXTRADELAY, OEEXTRADELAY, or WEEXTRADELAY parameter. This delay must be used carefully to prevent control-signal overlap between successive accesses to different chip-selects. This implies that the RDCYCLETIME and WRCYCLETIME are greater than the last control-signal deassertion time, including the extra half-GPMC_FCLK cycle.