CODEWITHSUNDEEP
vhdl
AdrianL
AdrianL

Reputation: 335

Unite two arrays

I want to make one array out of two.

TYPE        character_string IS array (0 TO 15) of unsigned (7 DOWNTO 0); 
TYPE        full_string IS array (0 TO 31) of unsigned (7 DOWNTO 0); 
SIGNAL  lcd_oben, lcd_unten             : character_string; 
SIGNAL  lcd_data                                : full_string;

And i want to take the two smaller arrays and put them togehter in the big one. Something like this:

lcd_data    <= lcd_oben & lcd_unten;

But that gives the error:

Error (10327): VHDL error at seqdec.vhd(55): can't determine definition of operator ""&"" -- found 0 possible definitions

Can anybody help?

Best regards Adrian

Upvotes: 3

Views: 91

Answers (1)

user1818839
user1818839

Reputation:

You have declared these as wholly unrelated array types, so you have told the compiler not to mix them together without type conversions.

I don't think that's really what you wanted to do.

Make both array types, subtypes of an unconstrained array, like array(<>) of unsigned(7 downto 0). Then they are not completely separate types and there should be a predefined & operator for them. 

TYPE        LCD_string IS array (natural range <>) of unsigned (7 DOWNTO 0); 
SUBTYPE     character_string IS LCD_String (0 TO 15);
SUBTYPE     full_string IS LCD_String (0 TO 31);

(Alternatively you can write your own & function which performs the necessary conversions; IMO this would be poor design).

Upvotes: 3

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