hib1 Posted September 25, 2014 Report Share Posted September 25, 2014 I raised this question earlier but received no replies re: "Introducing the Spartan 3E FPGA andVHDL." Please tell me what is the difference is between the UCF notation with < > symbols vs. the notation with " " symbols? notation 1 is in book, but notation 2 is in some other sample code I received. Also, it appears that "IOSTANDARD=LVTTL" is not required. notation 1 from the book:NET LED_1 LOC = "Pxx" | IOSTANDARD=LVTTL;NET LED_0 LOC = "Pyy" | IOSTANDARD=LVTTL; notation 2:NET "LED<1>" LOC="Pxx" NET "LED<0>" LOC="Pyy" Link to comment Share on other sites More sharing options...
mkarlsson Posted September 25, 2014 Report Share Posted September 25, 2014 Notation 1 specifies two signals, LED_1 and LED_2.Notation 2 specifies a bus LED with two signals. The corresponding HDL code must match the ucf file. VHDL: entity XXX is port ( LED : out std_logic_vector(1 downto 0); LED_1 : out std_logic; LED_2 : out std_logic; );end; Verilog: module XXX ( output [1:0] LED, output LED_1, output LED_2); Magnus Link to comment Share on other sites More sharing options...
hib1 Posted September 25, 2014 Author Report Share Posted September 25, 2014 Thanks for the quick response. Is a bus LED actually multiple LEDs addressable by separate bits? Link to comment Share on other sites More sharing options...
mkarlsson Posted September 25, 2014 Report Share Posted September 25, 2014 Yes, it could be, or a set of LEDs that you want to access as a group.For instance, having the LEDs in a 7-segment display on a bus makes it more convenient to set the digit to display vs. setting the individual segments on the display. Link to comment Share on other sites More sharing options...
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