JTAG SMT2 chain limit

[ks0ze]

Is there a limit on the number of devices the JTAG-SMT2 module can reliably have in the chain?

 

Thanks,

Dan

[sLowe]

Hey Dan,

It seems like the only real limiting factor is clocking signal integrity. Here is an answer from Xilinx to a similar question not using the JTAG-SMT2 module but has some good tips. They were having trouble getting consistent results with more than ten devices. The Xilinx answer goes into how they use a buffer to drive the clock nets to run 100 devices. So with some extra electronics, the JTAG chain can get pretty large! Would be interesting to try to empirically see how many devices the SMT2 could reliably drive alone.

Hope this helps!

Sam