Ebrahim Vakilpour wrote:
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It mans that two 8051s should stop their jobs and start talking to each other which I said before that's not what I’m looking for. I want an Async (or whatever you call it) communication so that 8051s do not interrupt each other for communication.


I think you are mixing up queueing and sync/async.

If you do not have a supervisor chip, your 8051 will have to stop whatever he is doing if a byte is sent for transmission in order to read (and accept) the byte. You will have to queue (read: buffer) your data if you do not want to treat your data immediately, but that is a plain (not always simple) buffer mechanism.

AN example:

If you are sending data to your printer, does he stop printing to receive the data? I don't think so.. It is receiving data into it's buffer, and yet it is printing.(and very likely using a parallel centronics or IEEE1284 I/F...)

So why should both your devices be tied up communicating? It is not so much a matter of sync/async functioning but more a question of throughput and the available cpu-time.

If your transmitter transmits a byte every second, then there is no reason for your processor to simply wait for a second, doing nothing, before receiving a second byte. Certainly so if it takes only a few machine-cycles to read a byte and save it in memory.

If however, you expect to sent a few Mbit/s (sustained), then you would "tie" up your processor, but then a fifo would be of no help...

So, going back to your protocol: If you do not want your 8051's being interrupted for communication, I think you'll need a supervisor chip with a buffer that will store the data until the 8051 is ready to read it.

What was the maximum throughput you were thinking of?

regards

Patrick