The Cortex-M3 used in the SAM3U has six code breakpoints and four general-purpose watchpoints, providing enough breakpoints for most cases of debugging. There are two debug interfaces, the JTAG and the Serial Wire. The serial wire is a 2-pin debug interface which enables asynchronous traces (data traces and profiling). The Cortex-M3 also allows live access to the core when the application is running, making it possible to read and write memory and to set or clear breakpoints on a running application.