Why does my Cyclone III FPGA fail to access the EPCS device using the EPCS Controller module?

Solution

In Cyclone® III devices, the EPCS controller does not automatically assign its output pins to the dedicated configuration pins on the FPGA. Instead, the output pins are exported to the top level design, giving users the flexibility to connect to any EPCS devices.

Therefore, in order to use the EPCS Configuration Controller the pins must be assigned manually, and the following settings must be made the Quartus® II software: 

1. Choose Settings from the Assignments menu
2. Click Device and Pin Options from the Device category
3. Click Dual-Purpose Pins and then make the following changes:

Data[0] -> Use as regular I/O
Data[1] -> Use as regularr I/O
DCLK -> Use as regular I/O
FLASH_nCE/nCS0 -> Use as regular I/O

You must check the device Pin-Out file for the Cyclone III device which you are using to make the following pins assignments:

data0_to_the_epcs_controller -> DATA0
sdo_from the_epcs_controller -> DATA1,ASDO
dclk_from_epcs_controller -> DCLK
sce_from_the_epcs_controller -> FLASH_nCE