Asynchronous Fifo - Empty flag implementation

[ankurbehl]

Hi All,

In my Asynchronous implementation, i am taking the following way for generating the FIFO_EMPTY (fifo_full is not required for my case)

Depth of FIFO - 2 to power

1: Write pointer (n+1 bit) is incremented in wr_clock domain.
2: Write pointer is grey coded.
3: Grey coded write pointer is passed through synchronized in rd_clock domain.
4: This grey coded synchronized write pointer is converted back to binary write pointer.
5: This binary write pointer is compared with the read pointer (n+1 bit) are compared to generate the FIFO_EMPTY condition.
6: The FIFO buffer write/read address are n bit and are always generated/assigned in binary format.

Does this look OK ?

Any weakness in this implementation ?

Thanks in anticipation for a quick feedback..

Regards
Ankur

 

[lalit_asic]

your design will work fine.
you can register output of grey to binary conveter.
it will increase maximum operating frequency(As empty flag is output, it should be registered).