After using Segger's RTT and SWO and stuff, nothing beats a plain old high speed UART pin for "basic" debugging. You can start up the UART, send your message an

After using Segger's RTT and SWO and stuff, nothing beats a plain old high speed UART pin for "basic" debugging. You can start up the UART, send your message and if there is inactivity after X milliseconds close the UART and the power consumption is back to microamps. It works with any micro and usb-serial chip so no lock-in with ARM or Segger related tools. However for some tasks such as proper debugging, stepping, or inspecting interrupt vectors while printing messages fast, native tools are the way to go.