Configuration Handbook - Kamami.pl

Configuring APEX 20KE & APEX 20KC DevicesYou can cascade several EPC2 or EPC1 devices to configure multipleAPEX 20KE or APEX 20KC devices. The first configuration device in thechain is the master configuration device, while the subsequent devices arethe slave devices. The master configuration device sends DCLK to theAPEX 20KE and APEX 20KC devices and to the slave configurationdevices. The first EPC device’s nCS pin is connected to the CONF_DONEpins of the FPGAs, while its nCASC pin is connected to nCS of the nextconfiguration device in the chain. The last device’s nCS input comes fromthe previous device, while its nCASC pin is left floating. When all datafrom the first configuration device is sent, it drives nCASC low, which inturn drives nCS on the next configuration device. Because a configurationdevice requires less than one clock cycle to activate a subsequentconfiguration device, the data stream is uninterrupted.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 7–7 shows how to configure multiple devices using cascadedEPC2 or EPC1 devices.Altera Corporation 7–17August 2005 Configuration Handbook, Volume 1