design a BCD Counter

Hi Gabra, sorry say this but I fear you need grasp digital design in deep as i usually told my pupils, error come from everywhere.

A BCD counter never count to 1010 that is ten decimal but remain in BCD domain {0..9} .

You can apply this method to ripple carry asyncronous reset but not to a syncronous counter as your appear to be.

This case require an enable count that happen on last digit value, when counter is 9 then load 0 as next state, at same time enable count on next digit. Your design miss this feature.

I suggest you start learning an HDL language and do this in a more simple fashion using state machine. I am proficient on VHDL and just read and understand Verilog I don't like so much, in HDL your design can be:

signal BCD : Std_Logic_Vector(3 downto 0);
 
 signal enable : Std_Logic := '1'; -- enable count
 
signal sreset : std logic := '0'; -- reset to 0 clock gated
 
 
 
BCD_counter: process (clock, reset_n)
 
var count : integer range 0 to 9 := 0;
 
if reset_n = '0' then
 
 count := 0; -- async reset
 
else
 
 If rising_edge(clock, reset_n) then
 
BCD <= Std_Logic_Vector(to_unsigned(count, 4));
 
if enable = '1' then
 
 if count = 9 or sreset = '1' then
 
 Count := 0;
 
else
 
 count := count +1;
 
end if; -- counter
 
end if; -- enable
 
end if; -- edge
 
end if; -- reset
 
end process;
 

Regards

hello again.

i know i'm not that knowledgeable when it comes too the digital systems part, but i'm doing my best with my limited time. and i end up getting to what i was looking for. but my problem is that we have this week off and i can't gt in contact with the lab assistants, plus the lecturer doesn't provide enough explanations to everything and with my limited knowledge, it takes some time to grasp it. but if only i can get you to help me for the last time. i'm at the last part of my circuit and i have all my parts ready. a part with bcd counter and a part with a digit shifter where it changes the locations of the digits on my fpga. but the thing is, i'm trying to connect them so that i can switch them with one button push, it worked but i have to hold the button to keep the shifter not just press it. i'm not quite sure what we need to use here, i'm thinking of a 2 to 1 multiplexer but then i'm not sure how to connect it.

i have attached all my project for you to check it and have more freedom working around it. if you could help me i appreciate it, if not, i understand.

thank you