3.9 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 4-4.

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 3-8. Atmel-ICE SWD Pin Mapping
NameAVR PORT PinSAM PORT PinDescription
SWDCLK14Serial Wire Debug Clock
SWDIO52Serial Wire Debug Data Input/Output
SWO36Serial Wire Output (optional - not implemented on all devices)
nSRST610Reset
VTG41Target voltage reference
GND2, 103, 5, 9Ground