Configuration Handbook - Kamami.pl

Configuration SchemesDo not drive CONF_DONE low after device configuration to delayinitialization. Instead, use the Enable User-Supplied Start-Up Clock(CLKUSR) option in the Device & Pin Options dialog box. You can usethis option to synchronize the initialization of multiple devices that arenot in the same configuration chain. Devices in the same configurationchain initialize together.After the first Stratix or Stratix GX device completes configuration duringmulti-device configuration, its nCEO pin activates the second Stratix orStratix GX device’s nCE pin, prompting the second device to beginconfiguration. Because CONF_DONE pins are tied together, all devicesinitialize and enter user mode at the same time. Because nSTATUS pinsare tied together, configuration stops for the whole chain if any device(including enhanced configuration devices) detects an error. Also, if theenhanced configuration device does not detect a high on CONF_DONE atthe end of configuration, it pulses its OE low for a few microseconds toreset the chain. The low OE pulse drives nSTATUS low on all Stratix andStratix GX devices, causing them to enter an error state. This state issimilar to a Stratix or Stratix GX device detecting an error.If the Auto-restart configuration after error option is on, the Stratix andStratix GX devices release their nSTATUS pins after a reset time-outperiod. When the nSTATUS pins are released and pulled high, theconfiguration device reconfigures the chain. If the Auto-restartconfiguration after error option is off, nSTATUS stays low until theStratix and Stratix GX devices are reset with a low pulse on nCONFIG.Figure 11–11 shows the FPP configuration with a configuration devicetiming waveform for Stratix and Stratix GX devices.11–24 Altera CorporationStratix Device Handbook, Volume 2 July 2005