I am programming for a device where there are two Analog Devices ADuC831 chips. One operates the communication for the device and the other does data acquisition. The Comm chip is the slave to the acquisit ion chip. This interface is something like this:
COMM (S) MAIN (M) SClock
As you have constrained it, no.
If you could arrange for another wire between the comm and main to flag the main chip when the comm had data waiting then yes.
If you can't then you're constrained to poll.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/ "Applied Control Theory for Embedded Systems" came out in April. See details at http://www.wescottdesign.com/actfes/actfes.html
Thanks for the input.
Actually, I should RTFM, because it turns out that my boss who designed this thing already planned out for this issue. He hooked up one of the pin outs to the external interrupt of the main chip. When I trigger that, THAT tells the system to start doing transfers from the comm chip.
So in my description I left something out.
-R
-------------------------------------------------- "It is human nature to take shortcuts in thinking"
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No. ( not unless you get clever with the SS line, and OR wire it, and pulse it briefly LOW from the slave, to say 'hey' and then the INT to master starts a slave transaction )
Yes. Normally you just include a null-packet as a slave present check, with no data.
-jg
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