cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
Highlighted
Adventurer
Adventurer
233 Views
Registered: ‎10-05-2015

JTAG traces length matching for Zynq 7000 SoC

Jump to solution

Hi,

I am using Zynq 7000 SoC (xc7z045-2ffg900c). What are the length matching requirements for the JTAG signals:TCK, TDO, TDI, and TMS? I am planning to run them at 24 MHz clock.

 

Thanks n Regards,

Binayak

 

0 Kudos
1 Solution

Accepted Solutions
Highlighted
215 Views
Registered: ‎01-22-2015

@binayak_shrestha 

What are the length matching requirements for the JTAG signals .... at 24 MHz clock

Trace length-differences can be a problem when signal propagation delay through the length-difference is a significant part of the clock period.

The period of your 24MHz clock is 41.66ns.  The typical propagation delay for a signal through a circuit board trace is about 2ns/ft (6.56ns/m).  A 1cm length-difference is equivalent to (0.01m * 6.56ns/m = 0.0656ns) which is only 100*0.0656/41.66 = 0.16% of your clock period. 

So, at a clock speed of 24MHz, if you keep the JTAG signal trace length-differences to less than 1cm then the JTAG interface should work properly.

Please also read the "Signal Integrity" section starting on page 28 of UG593.

Cheers,
Mark

View solution in original post

3 Replies
Highlighted
216 Views
Registered: ‎01-22-2015

@binayak_shrestha 

What are the length matching requirements for the JTAG signals .... at 24 MHz clock

Trace length-differences can be a problem when signal propagation delay through the length-difference is a significant part of the clock period.

The period of your 24MHz clock is 41.66ns.  The typical propagation delay for a signal through a circuit board trace is about 2ns/ft (6.56ns/m).  A 1cm length-difference is equivalent to (0.01m * 6.56ns/m = 0.0656ns) which is only 100*0.0656/41.66 = 0.16% of your clock period. 

So, at a clock speed of 24MHz, if you keep the JTAG signal trace length-differences to less than 1cm then the JTAG interface should work properly.

Please also read the "Signal Integrity" section starting on page 28 of UG593.

Cheers,
Mark

View solution in original post

Highlighted
Explorer
Explorer
209 Views
Registered: ‎05-11-2015

 

Besides the very educated answer from markg@prosensing.com , I would advise to have a length matching of 1-2 mm that is not difficult to achieve and will allow higher speeds if you ever need them.

---------------------------------------------------------------------------------------------------
Have you tried upgrading the operating system of your spirit level?
-------------------------------------------------------------------------------------------------
0 Kudos
Highlighted
Adventurer
Adventurer
135 Views
Registered: ‎10-05-2015

Thanks Mark and Joan for the help.

Regards,

Binayak

0 Kudos