Part Number: TMDSEMU110-U
Tool/software: Code Composer Studio
When updating CCS from v8 to v9, some changes were introduced to the JTAG Clock speed (TCLK) parameter of the XDS110 Debug Probes.
CCSV9.0.x
The TI Emulators package (emupack) that ships with CCSv9.0.x versions (8.1.0.000xx) has some jitter on the clock edges when running at 2.5MHz (the maximum speed of this version), which may cause very random communication errors with the target.
Although errors are not regularly seen with the common Launchpads, custom boards that feature longer cconnections or even the use of isolation adapters can cause the problem to manifest itself in the shape of errors 1170, PRSC and others.
The remedy for this is to lower the TCLK speed to 1.25MHz. This will reduce the jitter and should warrant a reliable connection.
Another alternative is to update the emupack to the newest release. But that also features an important change. Read on.
CCSv9.1.0
The TI Emulators package (emupack) that ships with CCSv9.1.x versions (8.2.0.000xx) changed the default TCLK speed.
With this new emupack, some performance improvements enable higher speeds up to 14MHz and the default is set to 8MHz, which was tested to be compatible with the Launchpads and development kits. However, this may be too high depending on the length of the connections, the use of isolation adapters and other physical factors.
In case there are problems, reduce the TCLK speed to the previous default of 2.5MHz and see if the connections can be made stable.
For details on how to change the TCLK speed, check section Advanced target configuration options
The contents of this text are also available at the section JTAG clock speed considerations of the XDS110 page at:
http://software-dl.ti.com/ccs/esd/documents/xdsdebugprobes/emu_xds110.html