48 www.xilinx.com Virtex-4 FPGA Configuration User GuideUG071 (v1.12) June 2, 2017Chapter 2: Configuration Interfaces RNon-Continuous SelectMAP Data LoadingNon-continuous data loading is used in applications where the configuration controllercannot provide an uninterrupted stream of configuration data—for example, if thecontroller pauses configuration while it fetches additional data.Configuration can be paused in two ways: by deasserting the CS_B signal (Free-RunningCCLK method, Figure 2-17) or by halting CCLK (Controlled CCLK method, Figure 2-18).Notes relevant to Figure 2-17:1. RDWR_B is driven Low by the user, setting the SelectMAP data pins as inputs forconfiguration. RDWR_B can be tied Low if readback is not needed. RDWR_B shouldnot be toggled after CS_B has been asserted, as this triggers an ABORT. (See“SelectMAP ABORT”).2. Device is ready for configuration after INIT_B toggles High.3. The user asserts CS_B Low, enabling SelectMAP data bus. CS_B signal can be tied Lowif there is only one device on the SelectMAP bus. If CS_B is not tied Low, it can beasserted at any time.4. BUSY goes Low shortly after CS_B is asserted. If CS_B is tied Low, BUSY is driven Lowbefore INIT_B toggles High.5. Byte loaded on rising CCLK edge.6. Byte loaded on rising CCLK edge.7. The user deasserts CS_B; byte ignored.8. The user deasserts CS_B; byte ignored.9. Byte loaded on rising CCLK edge.10. Byte loaded on rising CCLK edge.11. The user deasserts CS_B; byte ignored.12. Byte loaded on rising CCLK edge.13. Byte loaded on rising CCLK edge.14. Byte loaded on rising CCLK edge.Figure 2-17: Non-Continuous SelectMAP Data Loading with Free-Running CCLKPROGRAM_BINIT_BCCLKCS_BRDWR_BDATA[0:7]ug071_26_073007BUSY(2)(5) (6) (7) (8) (9) (10) (11) (12) (13) (14)(1)(3)(4)High-ZHigh-Z High-Z
