Re: 5510 EMIF - Can I use Asynchronous IF to connect to Synchronous Device ?

Scottie-

> I have a USB device hooked off my 5510s EMIF, and can use it quite
> happily using asynchronous mode on both DSP and USB device.

Small problem at this point... USB should be connected to either a) McBSP directly or
b) McBSP via small glue logic. For example, use a small CPLD or one of Lattice's
cool new small FPGAs with built-in config RAM, connect 8-bit parallel to USB device,
then use logic convert to McBSP serial stream. Logic if flexible and no trouble with
fastest possible USB synchronous bitrate.

-Jeff

> However, when the USB device runs in asynchronous mode it is not
> capable of reaching the high USB2 bandwidth figures I require. To
> achieve this, I need to run the DSP device in synchronous mode.
>
> Initially I thought, no problem, I'll just run the 5510s EMIF in
> synchronous mode. However it only offers SDRAM or SBSRAM as the
> default device types, and I cannot think of a way of addressing my
> USB devices registers using row/column addressing.
>
> Then I thought, what if i run the EMIF as Asynchronous and the USB
> device as Synchronous.
>
> To do so, I have connected DSP CLKOUT to the CLKIN on the USB
> device, and I'm running the CPU at 200MHz and CLKOUT/EMIF at 20MHz.
>
> However, it looks like I have no control over when my SETUP, STROBE
> and HOLD signals are asserted with respect to CLKOUT i.e. They can
> be triggered at any CPU clock edge within the CLKOUT period.
>
> Can anyone think of a good way to get around this problem ?
>
> Thanks in advance for any repsonse.
>
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