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eugen_pcad_ru
Observer
Observer
8,065 Views
Registered: ‎02-21-2011

SCSI interface on Spartan-3AN

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Hello all!

I'll try to do SCSI-interface on Spartan3-AN and translation my signals through cable to other devices. Frequency is about 40 MHz.

And I have a simple question:

What pin's IO standard  is corresponding SCSI-voltages:

 

1) single-ended (SE) voltage is corresponding ??? (Perhaps LVCMOS?)

2) high-voltage-differential (HVD) voltage is corresponding ???

3) low-voltage-differential (LVD) voltage is corresponding ???

 

Can I do every SCSI-interface on Spartan3-AN?

Who knows?

Thanks all!

 

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eteam00
Instructor
Instructor
10,216 Views
Registered: ‎07-21-2009

Is it possible cooperative using special LVD terminators chips and my simple (not SCSI, only voltage compatible) interface at 40 MHz?

To answer this question, you would need to provide more details describing your bus.  The TI termination device is probably a waste of your money.

 

What's left of your design problem is completely unrelated to FPGAs, FPGA design, Xilinx, and SCSI.  You are designing an interconnect bus, and you should solicit the help of someone knowledgeable in such things.

 

-- Bob Elkind

SIGNATURE:
README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369

Summary:
1. Read the manual or user guide. Have you read the manual? Can you find the manual?
2. Search the forums (and search the web) for similar topics.
3. Do not post the same question on multiple forums.
4. Do not post a new topic or question on someone else's thread, start a new thread!
5. Students: Copying code is not the same as learning to design.
6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please).
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bassman59
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Registered: ‎02-25-2008

 


@eugen_pcad_ru wrote:

Hello all!

I'll try to do SCSI-interface on Spartan3-AN and translation my signals through cable to other devices. Frequency is about 40 MHz.

And I have a simple question:

What pin's IO standard  is corresponding SCSI-voltages:

 

1) single-ended (SE) voltage is corresponding ??? (Perhaps LVCMOS?)

2) high-voltage-differential (HVD) voltage is corresponding ???

3) low-voltage-differential (LVD) voltage is corresponding ???

 

Can I do every SCSI-interface on Spartan3-AN?

Who knows?

Thanks all!

 


Do you know anything at all about SCSI?

 

----------------------------Yes, I do this for a living.
eugen_pcad_ru
Observer
Observer
8,045 Views
Registered: ‎02-21-2011

2bassman59:

Hello!

Thank you for interest to my post!

I know that high-speed interface into single device betweet several (up to 16) boards use LVD transmission (not SE and HVD).

Main problem is a fast (over 40 MHz) transmission in device. Interface is a very simle.

Therefore I need use terminators. Passive terminators are not recomended for fast transmission. Only active LVD SCSI terminators are good.

I think that LVD  is a voltage LVDS_25 (or LVDS_33). And terminators are chips like UCC5638 (or UCC5628).

Therefore if I'll use LVDS_33 standards on my boards and active LVD termintors I can guarantee fast transmission (without using crc or any noise combating codes).

 

 Thanks!

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eteam00
Instructor
Instructor
8,042 Views
Registered: ‎07-21-2009

I think the point which bassman was trying to make is this:

In your initial post you failed to distinguish between the several different versions of SCSI, which range from single-ended parallel to 3Gb/sec bit serial.  If you are designing for SCSI compatibility, a prudent and reasonable designer would be aware of (and specify) the various permutations of 'SCSI'.

-- Bob Elkind

SIGNATURE:
README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369

Summary:
1. Read the manual or user guide. Have you read the manual? Can you find the manual?
2. Search the forums (and search the web) for similar topics.
3. Do not post the same question on multiple forums.
4. Do not post a new topic or question on someone else's thread, start a new thread!
5. Students: Copying code is not the same as learning to design.
6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please).
7. You are not charged extra fees for comments in your code.
8. I am not paid for forum posts. If I write a good post, then I have been good for nothing.
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eugen_pcad_ru
Observer
Observer
8,040 Views
Registered: ‎02-21-2011

Hello!

Thanks for answers!

Let it be Ultra-320 SCSI compatible terminators and my personal interface (without CRC).

My question: Is it possible cooperative using special LVD terminators chips and my simple (not SCSI, only voltage compatible) interface at 40 MHz?

Thanks!

 

P.S.: Sorry for my simple (for you) question:)

P.P.S.: Perhaps I need read SCSI-specification or something else?

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eteam00
Instructor
Instructor
8,034 Views
Registered: ‎07-21-2009

Therefore if I'll use LVDS_33 standards on my boards and active LVD termintors.

What does 'active terminator' mean, in the context of differential signaling?  SCSI termination (passive or active) is for single-ended signals.  Differential signals are terminated across the diff pair.  Diff pairs have no use for 'SCSI active termination'.  And there is no such thing as 'active LVD termination'.

 

Good luck with your bus design.  Please find someone who understands multi-source, multi-drop bus design to help you.

 

-- Bob Elkind

SIGNATURE:
README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369

Summary:
1. Read the manual or user guide. Have you read the manual? Can you find the manual?
2. Search the forums (and search the web) for similar topics.
3. Do not post the same question on multiple forums.
4. Do not post a new topic or question on someone else's thread, start a new thread!
5. Students: Copying code is not the same as learning to design.
6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please).
7. You are not charged extra fees for comments in your code.
8. I am not paid for forum posts. If I write a good post, then I have been good for nothing.
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eugen_pcad_ru
Observer
Observer
8,021 Views
Registered: ‎02-21-2011

Perhaps not active. Sorry.
Thank you for answer.

 

For example look at datashet ucc5628 (http://media.digikey.com/PDF/Data%20Sheets/Texas%20Instruments%20PDFs/UCC5628.pdf) . This chip supports low voltage differential (LVD) termination (or SE, but not HVD).

Once nore my question: Is it possible cooperative using special LVD terminators chips and my simple (not SCSI, only voltage compatible) interface at 40 MHz?

 

Thanks!

________________________________________________________
Correctly formulated question is a one-half of answer
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eteam00
Instructor
Instructor
10,217 Views
Registered: ‎07-21-2009

Is it possible cooperative using special LVD terminators chips and my simple (not SCSI, only voltage compatible) interface at 40 MHz?

To answer this question, you would need to provide more details describing your bus.  The TI termination device is probably a waste of your money.

 

What's left of your design problem is completely unrelated to FPGAs, FPGA design, Xilinx, and SCSI.  You are designing an interconnect bus, and you should solicit the help of someone knowledgeable in such things.

 

-- Bob Elkind

SIGNATURE:
README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369

Summary:
1. Read the manual or user guide. Have you read the manual? Can you find the manual?
2. Search the forums (and search the web) for similar topics.
3. Do not post the same question on multiple forums.
4. Do not post a new topic or question on someone else's thread, start a new thread!
5. Students: Copying code is not the same as learning to design.
6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please).
7. You are not charged extra fees for comments in your code.
8. I am not paid for forum posts. If I write a good post, then I have been good for nothing.

View solution in original post

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eugen_pcad_ru
Observer
Observer
8,012 Views
Registered: ‎02-21-2011

Ok.

Thanks all for help!

Good luck!

 

________________________________________________________
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