Conversion error (integer to std_logic_vector) "Undefined symbol 'to_signed'"

Hi x_ao28,

I have noticed these with your code:

--- Quote Start ---

signal un : integer;

.

.

.

un<='0'; -- starts with 'units' in 0's

--- Quote End ---

you declared un as an integer but assigned a bit to it. I think you should remove the single quotation marks around the 0.

--- Quote Start ---

if (un <= 9) then -- check if units is less than or equal to 9

--- Quote End ---

I think this should be if (un = 9) then -- check if units is less than or equal to 9

Add use ieee.std_logic_signed.all; along with what you have and recompile and let's get the feedback.