SWD (Serial Wire Debug) is a lightweight alternative to JTAG debug port.
Serial Wire Debug (SWD) is an alternative 2-pin electrical interface that uses the same protocol. It uses the existing GND connection. SWD uses an arm CPU standard bi-directional wire protocol, defined in the ARM Debug Interface v5. This enables the debugger to become another amba bus master for access to system memory and peripheral or debug registers. Data rate is up to 4 Mbytes/sec at 50 MHz. SWD also has built-in error detection. On JTAG devices with SWD capability, the TMS and TCK are used as SWDIO and SWCLK signals, providing for dual-mode programmers.
