Convert a signed binary number into a signed one ?

[Rob1bureau]

Hello, I'm new in VHDL.


I have a basic question, but 3 hours of searches didn't provide any useful answer.

I got two SIGNALs, one unsigned, the other signed. I want to do something like :

SIGNAL Consigne_TMP : signed(7 DOWNTO 0);
SIGNAL Mot_Labview : unsigned(7 DOWNTO 0);

Mot_Labview(7) <= to_unsigned(Consigne_TMP(7), 8);

How should I do ?

 

[joris]

Uhm writing only Mot_Labview(7) doesn't need any "conversion" (just copies the individual bit) :

Mot_Labview(7) <= Consigne_TMP(7);

Copying a larger part does need a "conversion" (reinterpretation of the bits) :

Mot_Labview(6 downto 0) <= unsigned(Consigne_TMP(6 downto 0));

"to_unsigned" is used to "convert" an integer into an unsigned:

SIGNAL int_Mot_Labview : integer range -128 to 127;
SIGNAL Mot_Labview : unsigned(7 DOWNTO 0);

Mot_Labview <= to_unsigned(int_Mot_Labview, 8);