Configuration Handbook - Kamami.pl

Configuring Mercury, APEX 20K (2.5 V), ACEX 1K & FLEX 10K DevicesFigure 8–17. Multi-Device PPS Configuration Using a Microprocessor(1) V CC V CC (1)1 kΩ 1 kΩMemoryADDR DATA[7..0]MicroprocessorGNDAPEX 20K (2.5-V),ACEX 1K, Mercury, orFLEX 10K Device 1MSELOGNDAPEX 20K (2.5-V),ACEX 1K, Mercury, orFLEX 10K Device 2MSELOV CCV CCMSEL 1 MSEL 1CONF_DONECONF_DONEnSTATUSnSTATUSnCE nCEOnCEGNDDATA[7..0] DATA[7..0]DCLKDCLKnCONFIGnCONFIGNote to Figure 8–17:(1) The pull-up resistor should be connected to a supply that provides an acceptable input signal for all devices in thechain.In multi-device PPS configuration the first device’s nCE pin is connectedto GND while its nCEO pin is connected to nCE of the next device in thechain. The last device's nCE input comes from the previous device, whileits nCEO pin is left floating. After the first device completes configurationin a multi-device configuration chain, its nCEO pin drives low to activatethe second device’s nCE pin, which prompts the second device to beginconfiguration. The second device in the chain begins configuration withinone clock cycle; therefore, the transfer of data destinations is transparentto the microprocessor.Altera recommends keeping the configuration data valid on theDATA[7..0] bus for the 8 serializing clock cycles. The configuration datashould be held valid on the DATA bus for the complete byte periodbecause the nCEO of the first (and preceding) device can go low duringthe serializing DCLK cycles. Once the nCEO of the first (and preceding)device goes low, the second (and next) device becomes active and willbegin trying to accept configuration data. If the configuration data is notvalid on the first DCLK edge after nCEO goes low, then the second devicewill see incorrect configuration data and will never begin acceptingconfiguration data. This situation will only arise if you are sharing theDATA[7..0] bus with other system data such that the configuration datais only valid for a portion of the byte period.Altera Corporation 8–39August 2005 Configuration Handbook, Volume 1