Configuration Handbook - Kamami.pl

Passive Serial Configuration1 If you are using the optional CLKUSR pin and nCONFIG is pulledlow to restart configuration during device initialization, youneed to ensure that CLKUSR continues toggling during the timenSTATUS is low (maximum of 100ms).When the device is in user-mode, pulling the nCONFIG pin low initiatesa reconfiguration. The nCONFIG pin should be low for at least 2 ms. WhennCONFIG is pulled low, the device also pulls nSTATUS and CONF_DONElow and all I/O pins are tri-stated. Because CONF_DONE is pulled low, thisactivates the configuration device because it sees its nCS pin drive low.Once nCONFIG returns to a logic high level and nSTATUS is released bythe device, reconfiguration begins.Figure 11–22 shows how to configure multiple devices with an enhancedconfiguration device. This circuit is similar to the configuration devicecircuit for a single device, except Stratix III devices are cascaded formulti-device configuration.Figure 11–22. Multi-Device PS Configuration Using an Enhanced Configuration DeviceVCC(1) VCC (1)10 kΩ (3) 10 kΩ(3)V CCStratix III Device 2 Stratix III Device 1MSEL2MSEL1MSEL0DCLKDATA0nSTATUSCONF_DONEnCONFIGV CCMSEL2MSEL1MSEL0DCLKDATA0nSTATUSCONF_DONEnCONFIGEnhancedConfigurationDeviceDCLKDATAOE (3)nCS (3)nINIT_CONF (2)GNDN.C.nCEOnCEnCEOnCEGNDGNDNotes to Figure 11–22:(1) You should connect the pull-up resistor to the same supply voltage as the configuration device.(2) The nINIT_CONF pin is available on enhanced configuration devices and has an internal pull-up resistor that isalways active. This means you should not use an external pull-up resistor on the nINIT_CONF-nCONFIG line. Youdo not need to connect the nINIT_CONF pin if its functionality is not used. If you do not use nINIT_CONF, you mustpull nCONFIG to V CC through a 10-kΩ resistor.(3) The enhanced configuration devices' OE and nCS pins have internal programmable pull-up resistors. If you useinternal pull-up resistors, you should not use external pull-up resistors on these pins. The internal pull-up resistorsare used by default in the Quartus II software. To turn off the internal pull-up resistors, check the Disable nCS andOE pull-ups on configuration device option when generating programming files.11–54 Altera CorporationStratix III Device Handbook, Volume 1 May 2007