Configuration Handbook - Kamami.pl

Passive Serial ConfigurationDCLK, DATA0, and CONF_DONE) are connected to every device in thechain. Configuration signals can require buffering to ensure signalintegrity and prevent clock skew problems. Ensure that the DCLK andDATA lines are buffered for every fourth device. Because all deviceCONF_DONE pins are tied together, all devices initialize and enter usermode at the same time.Since all nSTATUS and CONF_DONE pins are tied together, if any devicedetects an error, configuration stops for the entire chain and you mustreconfigure the entire chain. For example, if the first device flags an erroron nSTATUS, it resets the chain by pulling its nSTATUS pin low. Thisbehavior is similar to a single device detecting an error.If the Auto-restart configuration after error option is turned on, thedevices release their nSTATUS pins after a reset time-out period(maximum of 100 ms). After all nSTATUS pins are released and pulledhigh, the MAX II device can try to reconfigure the chain without needingto pulse nCONFIG low. If this option is turned off, the MAX II device mustgenerate a low-to-high transition (with a low pulse of at least 2 ms) onnCONFIG to restart the configuration process.In your system, you can have multiple devices that contain the sameconfiguration data. To support this configuration scheme, all device nCEinputs are tied to GND, while nCEO pins are left floating. All otherconfiguration pins (nCONFIG, nSTATUS, DCLK, DATA0, and CONF_DONE)are connected to every device in the chain. Configuration signals canrequire buffering to ensure signal integrity and prevent clock skewproblems. Ensure that the DCLK and DATA lines are buffered for everyfourth device. Devices must be the same density and package. All deviceswill start and complete configuration at the same time. Figure 11–19shows multi-device PS configuration when both Stratix III devices arereceiving the same configuration data.11–46 Altera CorporationStratix III Device Handbook, Volume 1 May 2007