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Cascading PCI-DPs | Cypress Semiconductor

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Cascading PCI-DPs

Last Updated: August 28, 2009


- Can I connect 4 CY7C09449PV chips to PCI BUS at the same time in order to enlarge the accessing size (Up to 512KB) from PCI?

- Is depth or width expansion available with the PCI dual-port?

- Can multiple cards with the PCI-DP chip be used at the same time?


It is not recommended to depth or width expand multiple PCI-DP devices to increase the "shared" memory space so that it looks like a single larger memory device (on one PCI card, sharing the same PCI interface). This cannot be accomplished unless complex multiplexing logic is used to determine accesses (not recommended).  This is because a single PCI card has a set number of address/data lines and control signals which would need to be shared by all the PCI-DPs. 

However, it is possible to use multiple PCI-DPs on the same PCI bus (i.e. 4 individual devices on 4 separate cards).  Your PC enumerates each card on the PCI bus and treats them as individual devices.  However, this means that the data will not be "shared" among the multiple PCI-DP memories. 

Another option is to use one of Cypress's CPLDs and a PCI core as the interface to the PCI bus.  Then, you can attach a standard Cypress high density dual-port to the CPLD.

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