Visible to Intel only — GUID: iga1406293710373
Ixiasoft
Visible to Intel only — GUID: iga1406293710373
Ixiasoft
18.2. Functional Description
As shown below, the EPCS/EPCQA device's memory can be thought of as two separate regions:
- FPGA configuration memory—FPGA configuration data is stored in this region.
- General-purpose memory—If the FPGA configuration data does not fill up the entire EPCS/EPCQA device, any left-over space can be used for general-purpose data and system startup code.
-
By virtue of the HAL generic device model for flash devices, accessing the EPCS/EPCQA device using the HAL API is the same as accessing any flash memory. The EPCS/EPCQA device has a special-purpose hardware interface, so Nios II programs must read and write the EPCS/EPCQA memory using the provided HAL flash drivers.
The EPCS/EPCQA serial flash controller core contains an on-chip memory for storing a boot-loader program. When used in conjunction with Cyclone® and Cyclone® II devices, the core requires 512 bytes of boot-loader ROM. For Cyclone® III, Cyclone® IV, Intel® Cyclone® 10 LP, Stratix® II, and newer device families in the Stratix® series, the core requires 1 KByte of boot-loader ROM. The Nios® II processor can be configured to boot from the EPCS/EPCQA serial flash controller core. To do so, set the Nios® II reset address to the base address of the EPCS/EPCQA serial flash controller core. In this case, after reset the CPU first executes code from the boot-loader ROM, which copies data from the EPCS/EPCQA general-purpose memory region into a RAM. Then, program control transfers to the RAM. The Nios® II IDE provides facilities to compile a program for storage in the EPCS/EPCQA device, and create a programming file to program into the EPCS/EPCQA device.
For more information, refer to the Nios II Flash Programmer User Guide.
If you program the EPCS/EPCQA device using the Intel® Quartus® Prime Programmer, all previous content is erased. To program the EPCS/EPCQA device with a combination of FPGA configuration data and Nios II program data, use the Nios® II IDE flash programmer utility.
The Intel EPCS/EPCQA configuration device connects to the FPGA through dedicated pins on the FPGA, not through general-purpose I/O pins. In all Intel device families except Cyclone® III, Cyclone® IV, and Intel® Cyclone® 10 LP the EPCS/EPCQA serial flash controller core does not create any I/O ports on the top-level Platform Designer system module. If the EPCS/EPCQA device and the FPGA are wired together on a board for configuration using the EPCS/EPCQA device (in other words, active serial configuration mode), no further connection is necessary between the EPCS/EPCQA serial flash controller core and the EPCS/EPCQA device. When you compile the Platform Designer system in the Intel® Quartus® Prime software, the EPCS/EPCQA serial flash controller core signals are routed automatically to the device pins for the EPCS/EPCQA device.
You, however, have the option not to use the dedicated pins on the FPGA (active serial configuration mode) by turning off the respective parameters in the MegaWizard interface. When this option is turned off or when the target device is a Cyclone® III, Cyclone® IV device, or Intel® Cyclone® 10 LP you have the flexibility to connect the output pins, which are exported to the top-level design, to any EPCS/EPCQA devices. Perform the following tasks in the Intel® Quartus® Prime software to make the necessary pin assignments:
- On the Dual-purpose pins page (Assignments > Devices > Device and Pin Options), ensure that the following pins are assigned to the respective values:
- Data[0] = Use as regular I/O
- Data[1] = Use as regular I/O
- DCLK = Use as regular I/O
- FLASH_nCE/nCS0 = Use as regular I/O
- Using the Pin Planner (Assignments > Pins), ensure that the following pins are assigned to the respective configuration functions on the device:
- 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