Counter verification

[john]

Hi,

Process ( CLK, Reset_switch, Ch_Trig )
Begin
If ( Reset_switch = '1') then
channel_out <= (others =>'0');
Elsif ( Ch_Trig = '1') then
channel_out <= (others =>'0');
Elsif rising_edge ( CLK ) then
if ( ser_counter_in = "0010011") then
channel_out <= channel_out + 1;
Else
End if;
End if ;
End Process;

The above mentioned code generated the following RTL diagram

http://img253.imageshack.us/my.php?image=code3qi0.png

I have following questions

1. Is the RTL diagram according to my VHDL code?
2. I can not see the Adder and subtractor in detail. The quatrus is
showing them as blocks.
3. The multiplexer does not have a clock , though I did mention the
clock.

Please advice!
Thanks
John

 

[Dwayne Dilbeck]

1)Based on the fact I can't get all the signal names from the picture, I
would say the RTL diagram looks liek your code. Both Reset and ch_trig will
reset the counter on a high value. The counter increments when
ser_counter_in equals some value. Why are you using a diagram to verify
functionality? This is an error prone process. Do you have a self checking
Testbench? That would be a better way to verify things.

2)Uhm... what subtractor? your code and diagram doesn't show one. Why do you
need to see the logic implementation of the adder? You know the logic was
mapped to an adder that is what you want. You target is an FPGA not an ASIC.
It doesn't seem to matter if the adder is a Carry skip, carry look ahead,
and a cascading adder? It is mapping it to an FPGA primitive for adding.

3) The output of the MUX is clocked into the flops. The clock is there.

 

[Tricky]

2. I can not see the Adder and subtractor in detail. The quatrus is
showing them as blocks.

In FPGAs adders are not implemented in logic, they are implemented in
look-up tables (LUTS), as all logic is. So therfore, an adder is a
primitive. If you wanted to see the full implementation, look at the
technology map viewer. With newer version it will even let you look at
the logic implemented in each LUT.

 

[Dave Pollum]

Hi,

Process ( CLK, Reset_switch, Ch_Trig )
Begin
If ( Reset_switch = '1') then
channel_out <= (others =>'0');
Elsif ( Ch_Trig = '1') then
channel_out <= (others =>'0');
Elsif rising_edge ( CLK ) then
if ( ser_counter_in = "0010011") then
channel_out <= channel_out + 1;
Else
End if;
End if ;
End Process;

The above mentioned code generated the following RTL diagram

http://img253.imageshack.us/my.php?image=code3qi0.png

I have following questions

1. Is the RTL diagram according to my VHDL code?
2. I can not see the Adder and subtractor in detail. The quatrus is
showing them as blocks.
3. The multiplexer does not have a clock , though I did mention the
clock.

Please advice!
Thanks
John

Is there a separate process that increments or decrements your counter
"ser_counter_in"?
-Dave Pollum