Memory access via the JTAG-to-Avalon master bridge times out in System Console if the ratio of Avalon-MM input clock frequency to TCK frequency is less than two

Description

Memory access via the JTAG-to-Avalon master bridge times out in System Console if the frequency of the clock that feeds the Avalon memory-mapped (Avalon-MM) interface is less than 2x the frequency of the JTAG clock (TCK).

Resolution

Ensure that the frequency of the clock feeding the Avalon-MM interface is at least 2x higher than the TCK frequency.

Newer version of USB-Blaster II download cable has a default frequency of 24 MHz. To query TCK frequency of USB-Blaster II, run:

jtagconfig --getparam <cable> JtagClock

To change the TCK frequency to a valid frequency (that is, 16 MHz or 6 MHz), run:

jtagconfig --setparam <cable> JtagClock <frequency><unit>

For example: jtagconfig --setparam 1 JtagClock 6M

For more information on the USB-Blaster II downlaoad cable, refer to the USB-Blaster II Download Cable User Guide