Configuration Handbook - Kamami.pl

IntroductionTable 6–1. Configuration Options (Part 2 of 5)Device OptionEnable usersuppliedstart-upclock (CLKUSR)(Stratix series,Cyclone ® series,APEX TM II,APEX 20K, andMercury TM devicesonly).Option UsageThis option allows you toselect which clock source isused for initialization, eitherthe internal oscillator orexternal clocks provided onthe CLKUSR pin.Default Configuration(Option Off)The device’s internaloscillator (typically 10 MHz)supplies the initializationclock and the FPGA will takecare to provide itself withenough clock cycles forproper initialization.The CLKUSR pin is availableas a user I/O pin.Modified Configuration(Option On)The initialization clock mustbe provided on the CLKUSRpin. This clock cansynchronize the initializationof multiple devices. The clockshould be supplied when thelast data byte is transferred.Supplying a clock on CLKUSRwill not affect theconfiguration process.Enable usersuppliedstart-upclock (CLKUSR)(ACEX 1K, FLEX10K, and FLEX6000 devicesonly.)This option allows you toselect which clock source isused for initialization, eitherexternal clocks provided onthe CLKUSR pin or on theDCLK pin.In PS and PPS schemes, theinternal oscillator is disabled.Thus, external circuitry, suchas a configuration device ormicroprocessor, mustprovide the initialization clockon the DCLK pin.Programming files generatedby the Quartus II orMAX+PLUS II softwarealready have theseinitialization clock cyclesincluded in the file.In the PPA and PSAconfiguration schemes, thedevice’s internal oscillator(typically 10 MHz) suppliesthe initialization clock and theFPGA will take care toprovide itself with enoughclock cycles for properinitialization.The CLKUSR pin is availableas a user I/O pin.For more information on howmany clock cycles areneeded to properly initialize adevice, see the appropriatedevice family chapters.The initialization clock mustbe provided on the CLKUSRpin. This clock cansynchronize the initializationof multiple devices. The clockshould be supplied when thelast data byte is transferred.Supplying a clock on CLKUSRwill not affect theconfiguration process.For more information on howmany clock cycles areneeded to properly initialize adevice, see the appropriatedevice family chapters.6–6 Altera CorporationConfiguration Handbook, Volume 2 April 2007