Re: Why do some jtag drivers insert a transition to TAP_IR_PAUSE or TAP_DR_PAUSE in *_execute_scan function?

[Neil S. <nl...@ya...>]

 Sorry, hit send too soon.

Hello,

I've noticed that a number of JTAG drivers insert a transition to TAP_IRPAUSE or TAP_DRPAUSE in their _execute_scan functions. The OpenJTAG, armjtagew, buspirate, usbprog, and vsllink all do this. Other drivers such as ftdi bypass the pause state in certain conditions. I believe the reason behind it is to leave the JTAG state machine in a stable state between operations. Removing the mandatory pause for long operations can give a non-trivial performance boost. Is there any other reason to insert the pause state I'm not aware of?

Neil Shipp.     On Sunday, October 19, 2025 at 03:55:47 PM PDT, Neil Shipp <nl...@ya...> wrote: