4 stage register or fifo

[salman sheikh]

Hello,

I need a vhdl entity that allows me to write four x-bit values on a
periodic write signal and then read them out sequentially (in 4 clock
cycles) base on a read signal.

So you would have a diagram like something like this:

_ _ _ _
write _| |______| |______| |______| |________

value a b c d
_
read _____________________________________| |_______

value a b c d


Is this best implemented in a single small 4 word fifo or is there
another better approache?

Salman

 

[Francisco Camarero]

salman sheikh wrote:

Hello,

I need a vhdl entity that allows me to write four x-bit values on a
periodic write signal and then read them out sequentially (in 4 clock
cycles) base on a read signal.

So you would have a diagram like something like this:

_ _ _ _
write _| |______| |______| |______| |________

value a b c d
_
read _____________________________________| |_______

value a b c d


Is this best implemented in a single small 4 word fifo or is there
another better approache?

Do you need al the features of a FIFO? i.e:
Do you need to make use of 'empty' or 'full' flags ?
Do you always write _exactly_ four values before reading them out ?
Or may it happen that you write 6, then read out 4, then write in 2, then read
out 4...
basically,
What is the environment really requesting from your device ?

I definetly can help you, but you need to provide more info,

TechConSoul.

 

[salman sheikh]

Thanks for your reply. I have posted on this and other newsgroups with
questions that never go answered or replied to. I appreciate your time.

Don't need a empty or full flag. I just need to store four 35-bit words
somewhere and then, after waiting for another process to complete with
a valid signal, read them out sequentially in four consecutive clock
cycles, the first value written read out first. Maybe a fifo is overkill?

Salman

Francisco Camarero wrote:

salman sheikh wrote:

Hello,

I need a vhdl entity that allows me to write four x-bit values on a
periodic write signal and then read them out sequentially (in 4 clock
cycles) base on a read signal.

So you would have a diagram like something like this:

_ _ _ _
write _| |______| |______| |______| |________

value a b c d
_
read _____________________________________| |_______

value a b c d


Is this best implemented in a single small 4 word fifo or is there
another better approache?



Do you need al the features of a FIFO? i.e:
Do you need to make use of 'empty' or 'full' flags ?
Do you always write _exactly_ four values before reading them out ?
Or may it happen that you write 6, then read out 4, then write in 2, then read
out 4...
basically,
What is the environment really requesting from your device ?

I definetly can help you, but you need to provide more info,

TechConSoul.