Configuration Handbook - Kamami.pl

Passive Parallel Asynchronous ConfigurationIn your system, you may 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, DATA[7..1], nCS, CS, nWS,nRS and CONF_DONE) are connected to every device in the chain. Youshould pay special attention to the configuration signals because theymay require buffering to ensure signal integrity and prevent clock skewproblems. Specifically, ensure that the 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 8–22 showsmulti-device PPA configuration when both devices are receiving the sameconfiguration data.Figure 8–22. Multiple-Device PPA Configuration Using a Microprocessor When Both FPGAs Receive theSame DataV CC (2)(2) V CC1 kΩV CC (2)1 kΩAddress Decoder1 kΩADDRMemoryADDR DATA[7..0]V CC (2)1 kΩMicroprocessorMercury, APEX 20K (2.5-V),ACEX 1K or FLEX 10K DeviceDATA[7..0] nCEnCS (1)CS (1)GNDCONF_DONE DCLKnSTATUSnCEOnWSnRSnCONFIGRDYnBSYMSEL1MSEL0N.C. (3)V CCGNDMercury, APEX 20K (2.5-V),ACEX 1K or FLEX 10K DeviceDATA[7..0]nCS (1)DCLKCS (1)CONF_DONEnSTATUSnCEnWSnRSnCONFIGRDYnBSYnCEOMSEL1MSEL0N.C. (3)V CCNotes to Figure 8–22:(1) If not used, the CS pin can be connected to V CC directly. If not used, the nCS pin can be connected to GND directly.(2) The pull-up resistor should be connected to a supply that provides an acceptable input signal for all devices in thechain.(3) The nCEO pins of both devices are left unconnected when configuring the same configuration data into multipledevices.8–52 Altera CorporationConfiguration Handbook, Volume 1 August 2005