clock divider with counter

This involves a bit of speculation on my part since I don't know the details of your display but it looks like your module "hexadecimalcounter" is meant to take one 4-bit (=1 hex digit) and then display it in decimal format using two seven-segment display characters. What you want is a module that takes one 4-bit value and displays it in hex format using one seven segment display character. You can use one of those modules for the upper 4 bits of your counter and another for the lower 4 bits. Right now you are trying to put an 8 bit value into the module. Take a careful look at your hexadecimalcounter module, it looks like a functional module but not for what I think you want to do.