--- Quote Start ---
Correct. Is it (I believe) a non-bus master PLX chip.
--- Quote End ---
Then you are in luck.
The PLX chips normally have doorbell registers/interrupts for implemented an interlocked protocol. See page 7:
http://www.ovro.caltech.edu/~dwh/correlator/pdf/cobra_driver.pdf (
http://www.ovro.caltech.edu/%7edwh/correlator/pdf/cobra_driver.pdf)
That interlock acts as a mutex for access to the shared resource.
The key to understanding how this sort of protocol works, is to think of the protocol handshake in terms of transmitter-empty and receiver-ready interrupts.
The "character" being protected by this protocol can be multiple characters. In this example, the character is stored in a mailbox in the PLX chip. In the real driver, multiple mutexes are used, and protect different regions in shared SDRAM.
Cheers,
Dave
Honored Contributor
