HELP ! WHY doesn't SHL multiply by two ??

[Jam]

I don't get it:

I use the libraries:
Library IEEE;
Use IEEE.Std_logic_1164.all;
Use IEEE.Std_logic_unsigned.all;

I have a one compl ADC

temp(11 downto 0) <= (not FOCADCd(11) & FOCADCd(10 downto 0));

SAin(11 downto 0) <= SHL(temp,"10");

should this do the same as SAin(11 downto 0) <= SAin(11 downto 0) <=
(Temp(10 downto 0) & '0');

 

[rickman]

Jam wrote:

I don't get it:

I use the libraries:
Library IEEE;
Use IEEE.Std_logic_1164.all;
Use IEEE.Std_logic_unsigned.all;

I have a one compl ADC

temp(11 downto 0) <= (not FOCADCd(11) & FOCADCd(10 downto 0));

SAin(11 downto 0) <= SHL(temp,"10");

should this do the same as SAin(11 downto 0) <= SAin(11 downto 0) <=
(Temp(10 downto 0) & '0');

I am not totally clear on what you want to do in the above code. You
invert the msbit of your ADC input and then shift it left by two in the
same size word. This drops the top two bits of the original data.
Perhaps you need to define temp as 14 bits before you do the shift?
Also, it seems you think you are shifting by 1 bit while "10" specifies
two bit positions for the shift. I would do it this way.

temp(13 downto 0) <= (not FOCADCd(11) & FOCADCd(10 downto 0) & "00");

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[anupam]

Hi Pl tell me what do u want to do with this line

SAin(11 downto 0) <= SHL(temp,"10");

Anupam

 

[Martin Thompson]

"anupam" <anupam@coraltele.com> writes:

Hi Pl tell me what do u want to do with this line

SAin(11 downto 0) <= SHL(temp,"10");

Are you trying to do
SAin(11 downto 0) <= temp(10 downto 0) & '0';

?

Martin

--
martin.j.thompson@trw.com
TRW Conekt, Solihull, UK
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