Connecting to an SWD Target

The ARM SWD interface is a subset of the JTAG interface, making use of the TCK and TMS pins, which means that when connecting to an SWD device, the 10-pin JTAG connector can technically be used. The ARM JTAG and AVR JTAG connectors are, however, not pin-compatible, so this depends upon the layout of the target board in use. When using an STK600 or a board making use of the AVR JTAG pinout, the AVR connector port on the Atmel-ICE must be used. When connecting to a board, which makes use of the ARM JTAG pinout, the SAM connector port on the Atmel-ICE must be used.

The recommended pinout for the 10-pin Cortex Debug connector is shown in Figure 1.

Connection to a 10-pin 50-mil Cortex header

Use the flat cable (included in some kits) to connect to a standard 50-mil Cortex header.

Connection to a 10-pin 100-mil Cortex-layout header

Use the adapter board (included in some kits) to connect to a 100-mil Cortex-pinout header.

Connection to a 20-pin 100-mil SAM header

Use the adapter board (included in some kits) to connect to a 20-pin 100-mil SAM header.

Connection to a custom 100-mil header

The 10-pin mini-squid cable should be used to connect between the Atmel-ICE AVR or SAM connector port and the target board. Six connections are required, as described in the table below.

Table 1. Atmel-ICE SWD Pin Mapping
Name AVR port pin SAM port pin Description
SWDCLK 1 4 Serial Wire Debug Clock.
SWDIO 5 2 Serial Wire Debug Data Input/Output.
SWO 3 6 Serial Wire Output (optional- not implemented on all devices).
nSRST 6 10 Reset.
VTG 4 1 Target voltage reference.
GND 2, 10 3, 5, 9 Ground.