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FIFO overflow and underflow

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kumar91

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i just went through a problem in which there are a transmitter and a receiver both are working in different frequencies. now a FIFO is used in between them. there may be any phenomena FIFO overflow or FIFO underflow depending upon values of frequencies, which one is larger. now size of FIFO have to find out....???
 

That's not really a question, but here's an answer to a different question.

The AVERAGE input data rate CANNOT exceed the AVERAGE output data rate or you will eventually overflow unless you have a infinitely deep FIFO. Similarly, The AVERAGE output data rate CANNOT exceed the AVERAGE input data rate or you will eventually underflow.

The FIFO will only work if your data comes in bursts; you can't have continuous data in and out. You need to know your burst rate, frequencies, etc. to determine the appropriate size fifo. Maybe if you post more information we can help you.
 
ohk....but for better explaination u can take any value of frequencies and obviously for overfllow transmitter freq must be greater then receiver freq....and similarly for underflow receiver frequency must be greater than transmitter freq..
for example we can take
i) for overflow
transmitter freq=100Hz
receiver freq=25Hz
ii) for underflow
transmitter freq=25Hz
receiver freq=100Hz

now plz by using these values expalin how we can calculate size of FIFO for both cases.
 

You're missing some information: what is the burst size and burst rate? As I explained before, you CANNOT have a constant data flow or you will overflow/underflow your FIFO unless the read/write rates are identical. In other words, you can't have a data flowing in at a faster average rate than the data flowing out.
 

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