Configuration Handbook - Kamami.pl

Configuring APEX II DevicesYou can cascade several EPC2 or EPC1 devices to configure multipleAPEX II devices. The first configuration device in the chain is the masterconfiguration device, while the subsequent devices are the slave devices.The master configuration device sends DCLK to the APEX II devices andto the slave configuration devices. The first EPC device’s nCS pin isconnected to the CONF_DONE pins of the FPGAs, while its nCASC pin isconnected to nCS of the next configuration device in the chain. The lastdevice’s nCS input comes from the previous device, while its nCASC pinis left floating. When all data from the first configuration device is sent, itdrives nCASC low, which in turn drives nCS on the next configurationdevice. Because a configuration device requires less than one clock cycleto activate a subsequent configuration device, the data stream isuninterrupted.1 Enhanced configuration devices EPC4, EPC8, and EPC16 cannotbe cascaded.Since all nSTATUS and CONF_DONE pins are tied together, if any devicedetects an error, the master configuration device stops configuration forthe entire chain and the entire chain must be reconfigured. For example,if the master configuration device does not detect CONF_DONE going highat the end of configuration, it resets the entire chain by pulling its OE pinlow. This low signal drives the OE pin low on the slave configurationdevice(s) and drives nSTATUS low on all FPGAs, causing them to enter areset state. This behavior is similar to the FPGA detecting an error in theconfiguration data.Figure 6–7 shows how to configure multiple devices using cascadedEPC2 or EPC1 devices.Altera Corporation 6–15August 2005 Configuration Handbook, Volume 1