How to inject a crc_error into CycloneIV device

[ZhouTao_sf]

In AN539, a crc_error can be inject into a CycloneV device, when I do the same thing on a CycloneIV device, the crc_error pin pullup, but, when I pulldown nconfig(100us) , the crc_error pin pulldown 400ms after nconfig, and then  pullup after 50ms, in the same time,  conf_done keep low.

Is there any way to inject  a crc_error into CycloneIV device, and I can reload it by useing nconfig?

Thanks

[Karen763Purvis]

Hello!

No, you can't inject a CRC error into a Cyclone IV device and then simply reload it using the nconfig pin as you would with a Cyclone V. The Cyclone V is designed with advanced, in-system self-correction features that support this, while the Cyclone IV is not. For a Cyclone IV device, a CRC error places it in a configuration failure state, which requires a full reconfiguration cycle to recover from. The nconfig pin will only trigger the device to re-enter the configuration state, requiring you to then reload the entire .sof or .rbf file to get it working again. The delay you're seeing is the device preparing for that full reload.