The LPCXpresso IDE will attempt to identify when SWO trace configuration has not been successful and report details of what has gone wrong. Below are a list of common errors, together with details of what may have caused them:
SWO Trace functionality is only available when connecting to the target MCU using SWD. This message is displayed if you are connected via JTAG, in which case you will need to switch to using SWD. For most Cortex M3/M4 MCUs, debug connections are made using SWD by default so this message is not likely to be seen. However with LPC43xx parts, JTAG is used by default.
This message is displayed if you have not entered a clock setting value into the SWO Config view (typically leaving it set to 0).
This message is displayed if the LPCXpresso IDE has been unable to detect the channel used for SWO over the debug probe link. This typically suggest that your are using old or incompatible firmware. Disconnect your debug session, power down your debug probe and ensure that the debug probe is configured for dfu booting. Then when you start a new debug session, LPCXpresso should attempt to download the current redlink firmware.
This message is displayed if the LPCXpresso IDE has been unable to generate an appropriate SWO communication baud rate from the selected target clock speed. You may need to reconfigure your project to use a different clock speed.
This message is displayed if the LPCXpresso IDE has been unable to detect the channel used for SWO over the debug probe link. This typically suggest that your are using old or incompatible firmware. Disconnect your debug session, power down your debug probe and ensure that the debug probe is configured for dfu booting. Then when you start a new debug session, LPCXpresso should attempt to download the current redlink firmware.
This message is typically displayed if SWO not supported on this target or the selected target clock speed is wrong.
There is currently an issue with SWO Trace support on Mac OS X hosts such that if LPCXpresso IDE as been started from Launchpad, or by clicking on the lpcxpresso.app, then SWO Trace may not work. In such cases, LPCXpresso IDE will attempt to warn you that this may be because of how you started the IDE up. You should then try launching LPCXpresso IDE by clicking on the "install_dir/Open lpcxpresso" alias (or by running it from a terminal).