4.2.7 SWD

The ARM SWD interface is a subset of the JTAG interface, making use of TCK and TMS pins. The ARM JTAG and AVR JTAG connectors are however, not pin-compatible, so when designing an application PCB, which uses a SAM device with SWD or JTAG interface, it is recommended to use the ARM pinout shown in the figure below, and use the squid cable or an adapter to map to the AVR pinout used by the JTAGICE3. (There are no adapters available from Atmel to make this mapping.)

Figure 4-9. Recommended ARM SWD/JTAG Header Pinout

The JTAGICE3 is capable of streaming UART-format ITM trace to the host computer. Trace is captured on the TRACE/SWO pin of the 10-pin header (JTAG TDO pin). Data is buffered internally on the JTAGICE3 and is sent over the HID interface to the host computer. The maximum reliable data rate is approx. 1MB/s.