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OCIDEC-3 in verilog? Do PIO only accesses to hard drives workwithout DMA?
by Unknown on Jan 20, 2004
Not available!

Hello,

I am needing an IDE controller for my current SOC design and have been
looking at the Opencores OCIDEC core. I am unfamiliar with IDE
communication so I hope I don't ask a stupid question.

There are no stupid questions, only stupid answers.

We are needing to talk to 1.8" or 2.5" hard drives. All of the drives
we are looking at support the ATA (2-5) standards.

First question:
Is there verilog rtl code available for the OCIDEC-3 core?

No

I found the
VHDL version, but cannot find the verilog version. This core seems

the
best fit our target application, but I don't have time to convert the
VHDL to verilog.

Second question:
If there is no verilog version of the OCIDEC-3, will the OCIDEC-1 or 2
talk to hard drives, or are they just able to talk to Compact Flash /

PC
cards?

They can (and do) talk to harddisks. It's merely the other way around.
CF/PCCards can use the same protocol as harddisks.
PIO means Progammed IO, or in normal language: the CPU needs to take
care of the IO; moving the data from/to the device. If you need to
process a lot of data this can be quite a burden. However you can create
your own dma engine that handles this task for the CPU. To the DMA
controller it would appear is if it is talking to a FIFO.
Note that this is not the same as IDE-DMA modes!!

Work is in progress to create a newer, more flexible version of the
OCIDEC cores. This will be a one in all core, instead of having
increasingly complex cores (as is the case with OCIDEC-1,2,3) you simply
enable the options you need (and disable what you don't need).
PIO modes are working fine (and tested in hardware).
DMA modes are still under development.
If you can live with the beta-status of this core send me an email and I
will send you the files.

Richard

My intuition tells me that I could make the OCIDEC-1 or 2 work,
we just give up the DMA capability of the harddrive? Obviously this
would increase the CPU overhead to access the harddrive, but we can

live
with this. Basically, I need to know if we can talk to a current
harddrive using PIO transfers only, ignoring the DMA between the IDE
controller and the drive. PIO Mode 4 @ 16.6MB/s is plenty fast for

what
we need to do. We just need to be able to read/write to the drive. Thanks, Jeff Hanoch _______________________________________________ http://www.opencores.org/mailman/listinfo/cores





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