I have the following code:
process(value_counter, hex5_value)
begin
if(value_counter <= x"0F") then
with value_counter select hex4 <= --error on this line
"0111111" when x"00",
"0000110" when x"01",
"1011011" when x"02",
"1001111" when x"03",
"1100110" when x"04",
"1101101" when x"05",
"1111101" when x"06",
"0000111" when x"07",
"1111111" when x"08",
"1101111" when x"09",
"1110111" when x"0A",
"1111100" when x"0B",
"0111001" when x"0C",
"1011110" when x"0D",
"1111001" when x"0E",
"1110001" when x"0F";
hex5<="0111111";
elsif(value_counter > x"0F") then
with value_counter mod 10 select hex4 <=
"0111111" when x"00",
"0000110" when x"01",
"1011011" when x"02",
"1001111" when x"03",
"1100110" when x"04",
"1101101" when x"05",
"1111101" when x"06",
"0000111" when x"07",
"1111111" when x"08",
"1101111" when x"09",
"1110111" when x"0A",
"1111100" when x"0B",
"0111001" when x"0C",
"1011110" when x"0D",
"1111001" when x"0E",
"1110001" when x"0F";
with hex5_value select hex5 <=
"0111111" when x"00",
"0000110" when x"01",
"1011011" when x"02",
"1001111" when x"03",
"1100110" when x"04",
"1101101" when x"05",
"1111101" when x"06",
"0000111" when x"07",
"1111111" when x"08",
"1101111" when x"09",
"1110111" when x"0A",
"1111100" when x"0B",
"0111001" when x"0C",
"1011110" when x"0D",
"1111001" when x"0E",
"1110001" when x"0F";
end if;
end process;
but I am getting the following error on the indicated line when running it: Error (10500): VHDL syntax error at xxx near text "with"; expecting "end", or "(", or an identifier ("with" is a reserved keyword), or a sequential statement. Anyone know what's causing this, and how I can rewrite it legally and equivalently?
The "correct" answer is a CASE statement within a process or "with ... select" in the combinatorial region (i.e. outside a process).
But you would have much nicer VHDL if you created a constant array of 16 7-segment display values, and simply indexed the array :
subtype seven_seg is std_logic_vector(6 downto 0);
constant decode : array 0 to 15 of seven_seg := (
"0111111", "0000110", "1011011", "1001111",
"1100110", "1101101", "1111101", "0000111",
"1111111", "1101111", "1110111", "1111100",
"0111001", "1011110", "1111001", "1110001");
process(value_counter, hex5_value)
begin
if value_counter <= x"0F" then
hex4 <= decode(to_integer(value_counter(3 downto 0)));
hex5 <= decode(0);
-- elsif value_counter > x"0F" then
-- surely this "elsif" is unnecessary!
else
hex4 <= decode(to_integer(value_counter(7 downto 4)));
hex5 <= decode(to_integer(hex5_value(3 downto 0)));
end if;
end process;