51.7 Programming and Debug Ports

For programming and/or debugging the SAM L21, the device should be connected using the Serial Wire Debug, SWD, interface. Currently the SWD interface is supported by several Atmel and third party programmers and debuggers, like the Atmel-ICE, SAM-ICE, JTAGICE3 or SAM L21 Xplained Pro (SAM L21 evaluation kit) Embedded Debugger.

Refer to the Atmel-ICE, SAM-ICE, JTAGICE3 or SAM L21 Xplained Pro user guides for details on debugging and programming connections and options. For connecting to any other programming or debugging tool, refer to that specific programmer or debugger’s user guide.

The SAM L21 Xplained Pro evaluation board supports programming and debugging through the onboard embedded debugger so no external programmer or debugger is needed.

Note: A pull-up resistor on the SWCLK pin is critical for reliable operation. Refer to related link for more information.
Figure 51-11. SWCLK Circuit Connections
Table 51-9. SWCLK Circuit Connections
Pin NameDescriptionRecommended Pin Connection
SWCLKSerial wire clock pinPull-up resistor 1kΩ