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Observer
Observer
9,138 Views
Registered: ‎03-20-2013

Spartan6 SPI configuration sanity check

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Hi,

I'm finalizing a schematic before sent for layout.  I was hoping to get a sanity check on the connections.

 

I'm using the LX9 in the TQ144 package and have:

 

Pin 65 (IO_L3P_D0_DIN_MISO_MISO1_2) connected to the flash's MISO.

Pin 64 (IO_L3N_MOSI_CSI_B_MISO0_2) connected to the flash's MOSI

Pin 38 (IO_L65N_CSO_B_2) conected to the slave select line

Pin 70 (IO_L1P_CCLK_2) connected to sclk

 

Sorry for the simple question, but given the myriad pins with their multiple functions I just want to make sure I get this right.  Thanks!

 

D

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Instructor
Instructor
15,450 Views
Registered: ‎07-21-2009

series termination resistors are ideally placed near the signal source (driver).

parallel termination resistors are ideally placed at the very end of the signal trace furthest from the signal source.

do not use series termination for multi-load signals, only for signals with single source and single load.

 

There are more layout guidelines, depending on your schematic design, but these are the most useful ones for the configuration connections.

 

-- Bob Elkind

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Instructor
Instructor
9,136 Views
Registered: ‎07-21-2009

The connections you list are superficially correct, but too incomplete to guarantee success.  The guide for you should be UG380 Figure 2-12.  Are there any differences between Figure 2-12 and your board design?  If so, suggest you list each of these differences and post them to this thread for review.

 

-- 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.
Observer
Observer
9,118 Views
Registered: ‎03-20-2013

Thanks for your reply, Bob.  Everything else looks like the Figure 2-12.  I just wanted to sanity check the MISO/MOSI pins given the myriad number of pins that contain the words "MISO" and "MOSI" in their names.  Much appreciated.

 

D

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Instructor
Instructor
9,113 Views
Registered: ‎07-21-2009

Do you know what directions to give to the layout designer for placement of termination resistors?

 

-- 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.
Observer
Observer
9,103 Views
Registered: ‎03-20-2013

The guide provies some reasonable guidelines.  I figured I could send that along with the layout guide (UG393).  Looks like the main constraint is the parallel termination and no stubs.  Is there any other info you'd recommend passing along/looking for?  Thanks so much for your help!

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Instructor
Instructor
15,451 Views
Registered: ‎07-21-2009

series termination resistors are ideally placed near the signal source (driver).

parallel termination resistors are ideally placed at the very end of the signal trace furthest from the signal source.

do not use series termination for multi-load signals, only for signals with single source and single load.

 

There are more layout guidelines, depending on your schematic design, but these are the most useful ones for the configuration connections.

 

-- 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

Observer
Observer
9,087 Views
Registered: ‎03-20-2013

Thanks so much for your help, Bob.  Much appreciated.

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