描述

When I try to perform the simulation on SPI_ACCESS using ISim, I see the following error:

** Failure:DRC Error : In SPI_ACCESS opcode is not recognized

User(VHDL) Code Called Simulation Stop

In process unisim_VITAL.vhd:186631

What does "opcode" refer to? Why does this error pop up?

解决方案

The opcode means the first byte of the command that you send to the MOSI of SPI_ACCESS.

The error messages indicate that the opcode is either unsupported in simulation or an invalid opcode.

The supported opcode list can be found in Table 1-4 of the "Spartan-3AN FPGA In-System Flash User Guide" (UG333):

http://www.xilinx.com/support/documentation/user_guides/ug333.pdf