6

Atmel AVR1923

8394B-AVR-02/12

4 Connectors

The Atmel AVR XMEGA-A3BU Xplained kit has five 10-pins, 100mil headers. One

header is used for programming the Atmel AVR ATxmega256A3BU, and the others

are used to access spare analog and digital pins on the Atmel AVR XMEGA

(expansion headers).

4.1 Programming headers

The XMEGA can be programmed and debugged by connecting an external

programming/debugging tool to the “JTAG & PDI” header shown in Figure 3-1. The

header has a standard pin-out and therefore tools like the Atmel JTAGICE 3 or Atmel

AVR ONE! can be connected to the header.

Due to physical differences of the Atmel AVR JTAGICE mkII and AVR ONE! probes,

the PCB has an opening below the JTAG and PDI header. This is to make room for

the orientation tap on the JTAGICE mkII probe.

The grey female 10-pin header on JTAGICE mkII has to be used when connecting to

the kit. The opening in the board is made to fit the orientation tab on the header.

When using PDI with the JTAGICE mkII it is necessary to use the squid cable.

A standoff adapter (no. 1) is needed when using AVR ONE!

Pin 1 on the JTAG header is at the top right corner and is marked with a square pad.

Table 4-1. XMEGA programming and debugging interface – JTAG and PDI.

Pin on programming header

JTAG

(1)

PDI

(2)

1

TCK

-

2

GND

GND

(3)

3

TDO

DATA

4

VCC

VCC

5

TMS

-

6

nSRST

CLK

7

-

-

8

-

-

9

TDI

-

10

GND

GND

(3)

Notes:

1. Standard pin-out for JTAGICE mkII and other Atmel programming tools.

2. Requires adapter (squid cable) to connect a JTAGICE mkII.

3. It is only required to connect to one GND pin.

Because JTAG TDO and PDI DATA are connected on the PCB for this kit, JTAG

must be disabled on the device in order to use PDI. The reason for this is that when

JTAG is enabled it will enable a pull-up internally on TDO which interferes with the

PDI initialization sequence.

This will also be an issue when the application on the device uses the JTAG_TDO

pin. Nevertheless it is possible to use the pin if the TDO signal is disconnected from

the PDI DATA signal by cutting a strap (the cut-strap J203 is on the back side of the

board and marked with a text that describes its function) on the back side of the PCB.