offset binary to signed converter for ADC

Invert the sign bit is the solution i use with logical gates, before my investigation on CONV_SIGNED fnction.

I stop trying to understand convert function. I keep the basic solution in vhdl :

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.STD_LOGIC_ARITH.ALL;

use IEEE.STD_LOGIC_UNSIGNED.ALL;

ENTITY INVBITBUS IS

PORT(

a_bus : IN bit_vector(2 downto 0);

s_bus : OUT bit_vector(2 downto 0));

SIGNAL a, b ,c : BIT;

END INVBITBUS ;

ARCHITECTURE dataflow OF INVBITBUS IS

BEGIN

a <= a_bus(2);

b <= a_bus(1);

c <= a_bus(0);

s_bus (2) <= NOT (a);

s_bus (1) <= b;

s_bus (0) <= c;

END dataflow ;