Answers Database
FPGA Express: How to assign standard logic vectors as Hex or Octal values
Record #4376
Product Family: Software
Product Line: Synopsys
Product Part: Foundation FPGA Express
Problem Title:
FPGA Express: How to assign standard logic vectors as Hex or Octal values
Problem Description:
Urgency: Standard
General Description:
When assigning std_logic_vectors a Hex value within FPGA Express 2.x like so:
dout<=X"F0";
the following Error is returned
Error L20/C0 : #0 Error: <file>.vhd line <x> Can not determine type of right
hand side. The following interpretations were considered for the right hand
side: (none). (VSS-1049) (FE-dm-hdlc-unknown)
This problem has been fixed in FPGA Express 3.0, although leaving the
conversion function in will give an error. See (Xilinx Solution 640) for more
details.
Solution 1:
Direct assignments as hex values are not supported in FPGA Express 2.x.
There is a function (To_X01) in std_logic_1164.all to convert.
Example:
dout <= to_x01(X"F0");
With FPGA Express 3.0 and newer, the conversion function is not needed:
dout <= X"FO";
End of Record #4376 - Last Modified: 03/17/99 13:47 |
