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PCMCIA interface

Hi everybody,

A part of a project I'm designing is a PCMCIA bus card with a 32 bit data system bus. The system included in the card has a multicore DSP, an ARM processor, some NOR FLASH, SDRAM memory and a FPGA. The FPGA is used for the PCMCIA interface to the system bus and some high speed math as a companion for DSP. The purpose of the whole PCMCIA interface is to transfer some data from the SDRAM into PC, in real time at 33Mhz clock rate. The card data system bus is running at 133MHz.

How you'll chose the design for the best card bus interface, knowing there are some fast processes on the internal bus:

a. using the FPGA as a slave memory selected by the DSP and implementing a FIFO inside the FPGA . An interrupt request will notice the PC to start download data and empty the FIFO. b. using DMA control over the system bus from the FPGA (FPGA as master, DSP as slave) c. other (please detail)

thank you, Vasile

Reply to
vasile
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There's a number of things you haven't mentioned (the actual data bandwidth?) although you say you need to transfer data at 33MHz - is that a continuous throughput rate?

What else is connected to this memory bus? Many interfaces use the same bus lines as the main memory system. What controller is being used? How many clocks (minimum) per bus transaction?

All these impact the choice of interface.

The simplest is a simple memory device; much more complex is DMA access to a dual ported RAM. Which of those (or something in between) needs some numbers.

Specific numbers:

Throughput from FPGA (over time) Is the burst rate from the FPGA critical? (If so, it impacts the interface) Devices connected to the interface bus Bus type (specifies the bus cycle information)

That would be a good start :)

Cheers

PeteS

Reply to
PeteS

When transferring data from the FPGA to or from PC system memory, implementing bus mastering within the FPGA will provide much higher data bandwidth. You don't want to use a slave interface for that purpose.

Reply to
Duane Clark

Even if you implement Cardbus (essentially PCI) rather than PCMCIA(essentially ISA) you won't get continuous 33MHz transfer other than short periods of time. ExpressCard format can go this fast providing the architecture behind it can support that data rate.

John Adair Enterpo> Hi everybody,

Reply to
John Adair

Hi John, I didn't heard about this standard before. It's compatible with most PCMCIA interfaces available on laptops ? There is somewhere a documentation available ?

thx, Vasile

Reply to
vasile

It's unrelated to PCMCIA and is completely incompatible, having a different connector. A few recent laptops support it, and it will probably (eventually) replace PCMCIA. In the meantime we have the joy of "legacy-free"!

Reply to
zwsdotcom

Cardbus is a forward progression path from PCMCIA. Have a look at

formatting link
for the specifications. They do cost unfortunately. The connector for PCMCIA/Cardbus has features to identify which sort of card is plugged in and that is in the spec. There are host controllers from companies like TI if you want some other sources of info. I think Mindshare might have a book too that is worth having.

Most laptops made in the last few years, with a "PCMCIA", support the Cardbus extension of the standard.

Expresscard is mechanically incompatible and is basically a replacement for PCMCIA/Cardbus and is the laptop equivalent of PCI-E. It is very rapidly replacing PCMCIA/Cardbus in new laptops.

John Adair Enterpo> John Adair wrote:

Reply to
John Adair

Just one small clarification:

Expresscard is not "equivalent" to PCIe: the connector actually provides both PCIe x1 and USB 2.0 ports, allowing each Expresscard slot to house either PCIe or USB based devices... or possibly both at once, should someone find a need for that.

S>

Reply to
Daniel S.

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