3.6 Connecting to an SWD Target
The ARM SWD interface is s subset of the JTAG interface, making use of 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 STK600 or a board making use of the AVR JTAG pinout, the standard JTAG connector can be used. When connecting to a board which makes use of the ARM JTAG pinout, the 10-pin "mini-squid" cable must be used. (There are no adapters available from Atmel to make this mapping.)
| JTAGICE3 pin | Target pins | Mini-squid pin | ARM SWD pin |
|---|---|---|---|
| Pin 1 (TCK) | SWDCLK | 1 | 4 (SWDCLK) |
| Pin 2 (GND) | GND | 2 | 3, 5, 9 (GND) |
| Pin 3 (TDO) | SWO (optional) | 3 | 6 |
| Pin 4 (VTG) | VTG | 4 | 1 (VCC) |
| Pin 5 (TMS) | SWDIO | 5 | 2 (SWDIO) |
| Pin 6 (nSRST) | RESET | 6 | 10 (nRESET) |
| Pin 7 (Not connected) | 7 | ||
| Pin 8 (nTRST) | 8 | ||
| Pin 9 (TDI) | 9 | ||
| Pin 10 (GND) | 0 | 3, 5, 9 (GND) |