4.2.2.1 SAM JTAG Pinout (Cortex®-M debug connector)

When designing an application PCB which includes a Microchip SAM with the JTAG interface, it is recommended to use the pinout as shown in the figure below. Both 100-mil and 50-mil variants of this pinout are supported, depending on the cabling and adapters included with the particular kit.

Figure 4-2. SAM JTAG Header Pinout
Table 4-1. SAM JTAG Pin Description
NamePinDescription
TCK4Test Clock (clock signal from the Atmel-ICE into the target device)
TMS2Test Mode Select (control signal from the Atmel-ICE into the target device)
TDI8Test Data In (data transmitted from the Atmel-ICE into the target device)
TDO6Test Data Out (data transmitted from the target device into the Atmel-ICE)
nRESET10Reset (optional). Used to reset the target device. Connecting this pin is recommended since it allows the Atmel-ICE to hold the target device in a Reset state, which can be essential to debugging in certain scenarios.
VTG1Target voltage reference. Atmel-ICE samples the target voltage on this pin to power the level converters correctly. The Atmel-ICE draws less than 1 mA from this pin in this mode.
GND3, 5, 9Ground. All must be connected to ensure that the Atmel-ICE and the target device share the same ground reference.
KEY7Connected internally to the TRST pin on the AVR connector. Recommended as not connected.
Tip: Remember to include a decoupling capacitor between pin 1 and GND.