Question I have is I need a 42X1 Mux Actually I am muxing 42 16 bit databusses. The Timing is critical because the 42 16 bit words are read by a microcontroller. I am wondering the best way to MUX theses signals. I could use a 64X1 mux and syntesize out unused logic. Or I could use a 32X1, 16X1 with a 2X1 to merge the two muxed data paths. Does it make any difference at all what I do? Any other alternative approaches? Thank You, Gary Olson
I meant the timing is not critical because I am reading the Mux output with a Microcontroller.
Gary, Ken Chapman of Xilinx wrote a TechXclusive about Multiplexers. It's worth a read. cheers, Syms.
Here is my VHDL library IEEE; use IEEE.STD_LOGIC_1164.all; entity MUX42 is port ( dIn_0 : in STD_LOGIC_VECTOR (15 downto 0); dIn_1 : in STD_LOGIC_VECTOR (15 downto 0);
dIn_2 : in STD_LOGIC_VECTOR (15 downto 0); dIn_3 : in STD_LOGIC_VECTOR (15 downto 0); dIn_4 : in STD_LOGIC_VECTOR (15 downto 0); dIn_5 : in STD_LOGIC_VECTOR (15 downto 0); dIn_6 : in STD_LOGIC_VECTOR (15 downto 0); dIn_7 : in STD_LOGIC_VECTOR (15 downto 0);dIn_8 : in STD_LOGIC_VECTOR (15 downto 0); dIn_9 : in STD_LOGIC_VECTOR (15 downto 0);
dIn_10 : in STD_LOGIC_VECTOR (15 downto 0); dIn_11 : in STD_LOGIC_VECTOR (15 downto 0); dIn_12 : in STD_LOGIC_VECTOR (15 downto 0); dIn_13 : in STD_LOGIC_VECTOR (15 downto 0); dIn_14 : in STD_LOGIC_VECTOR (15 downto 0); dIn_15 : in STD_LOGIC_VECTOR (15 downto 0); dIn_16 : in STD_LOGIC_VECTOR (15 downto 0); dIn_17 : in STD_LOGIC_VECTOR (15 downto 0); dIn_18 : in STD_LOGIC_VECTOR (15 downto 0); dIn_19 : in STD_LOGIC_VECTOR (15 downto 0); dIn_20 : in STD_LOGIC_VECTOR (15 downto 0); dIn_21 : in STD_LOGIC_VECTOR (15 downto 0); dIn_22 : in STD_LOGIC_VECTOR (15 downto 0); dIn_23 : in STD_LOGIC_VECTOR (15 downto 0);dIn_24 : in STD_LOGIC_VECTOR (15 downto 0); dIn_25 : in STD_LOGIC_VECTOR (15 downto 0);
dIn_26 : in STD_LOGIC_VECTOR (15 downto 0); dIn_27 : in STD_LOGIC_VECTOR (15 downto 0); dIn_28 : in STD_LOGIC_VECTOR (15 downto 0); dIn_29 : in STD_LOGIC_VECTOR (15 downto 0); dIn_30 : in STD_LOGIC_VECTOR (15 downto 0); dIn_31 : in STD_LOGIC_VECTOR (15 downto 0); dIn_32 : in STD_LOGIC_VECTOR (15 downto 0); dIn_33 : in STD_LOGIC_VECTOR (15 downto 0); dIn_34 : in STD_LOGIC_VECTOR (15 downto 0); dIn_35 : in STD_LOGIC_VECTOR (15 downto 0); dIn_36 : in STD_LOGIC_VECTOR (15 downto 0); dIn_37 : in STD_LOGIC_VECTOR (15 downto 0);dIn_38 : in STD_LOGIC_VECTOR (15 downto 0); dIn_39 : in STD_LOGIC_VECTOR (15 downto 0);
dIn_40 : in STD_LOGIC_VECTOR (15 downto 0); dIn_41 : in STD_LOGIC_VECTOR (15 downto 0); sel_0 : in STD_LOGIC; -- select mux input sel_1 : in STD_LOGIC; -- select mux inputsel_2 : in STD_LOGIC; -- select mux input sel_3 : in STD_LOGIC; -- select mux input
sel_4 : in STD_LOGIC; -- select mux input sel_5 : in STD_LOGIC; -- select mux input
dOut : out STD_LOGIC_VECTOR (15 downto 0) ); end MUX42; --}} End of automatically maintained section architecture MUX42 of MUX42 is signal adr: std_logic_vector(5 downto 0);begin adr <= sel_5 & sel_4 & sel_3 & sel_2 & sel_1 & sel_0; with adr select dOut<= dIn_0 when "000000", dIn_1 when "000001", dIn_2 when "000010", dIn_3 when "000011", dIn_4 when "000100", dIn_5 when "000101", dIn_6 when "000110", dIn_7 when "000111", dIn_8 when "001000", dIn_9 when "001001", dIn_10 when "001010", dIn_11 when "001011", dIn_12 when "001100", dIn_13 when "001101", dIn_14 when "001110", dIn_15 when "001111", dIn_16 when "010000", dIn_17 when "010001", dIn_18 when "010010", dIn_19 when "010011", dIn_20 when "010100", dIn_21 when "010101", dIn_22 when "010110", dIn_23 when "010111", dIn_24 when "011000", dIn_25 when "011001", dIn_26 when "011010", dIn_27 when "011011", dIn_28 when "011100", dIn_29 when "011101", dIn_30 when "011110", dIn_31 when "011111", dIn_32 when "100000", dIn_33 when "100001", dIn_34 when "100010", dIn_35 when "100011", dIn_36 when "100100", dIn_37 when "100101", dIn_38 when "100110", dIn_39 when "100111", dIn_40 when "101000", dIn_41 when
--
--Ray Andraka, P.E. President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950 email snipped-for-privacy@andraka.com"They that give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -Benjamin Franklin, 1759
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.