vhdl - Unite two arrays -

i want make 1 array out of two.

type        character_string array (0 15) of unsigned (7 downto 0);  type        full_string array (0 31) of unsigned (7 downto 0);  signal  lcd_oben, lcd_unten             : character_string;  signal  lcd_data                                : full_string; 

and want take 2 smaller arrays , put them togehter in big one. this:

lcd_data    <= lcd_oben & lcd_unten; 

but gives error:

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

can help?

best regards adrian

you have declared these wholly unrelated array types, have told compiler not mix them without type conversions.

i don't think that's wanted do.

make both array types, subtypes of unconstrained array, array(<>) of unsigned(7 downto 0). not separate types , there should predefined & operator them.

type        lcd_string array (natural range <>) of unsigned (7 downto 0);  subtype     character_string lcd_string (0 15); subtype     full_string lcd_string (0 31); 

(alternatively can write own & function performs necessary conversions; imo poor design).