Atmel AVR XMEGA-A3BU Installation and operating instructions

Atmel AVR1923: XMEGA-A3BU Xplained
Hardware User Guide
Features
• Atmel®AVR®ATxmega256A3BU microcontroller
• FSTN LCD display with 128x32 pixels resolution
• Battery backup
• Analog sensors
- Ambient light sensor
- Temperature sensor
• Analog filter
• Digital I/O
- Three mechanical buttons
- Two user LEDs, one power LED and one status LED
- Four expansion headers
• Touch
- One Atmel AVR QTouch®button
• Memory
- Atmel AVR AT45DB642D DataFlash®serial flash
• Footprints for external memory
- Atmel AVR AT25DF series industry standard serial flash
1 Introduction
The Atmel AVR XMEGA-A3BU Xplained evaluation kit is a hardware platform to
evaluate the Atmel ATxmega256A3BU microcontroller.
The kit offers a large range of features that enables the Atmel AVR XMEGA®user
to get started using XMEGA peripherals right away and understand how to
integrate the XMEGA device in their own design.
Figure 1-1. XMEGA-A3BU Xplained evaluation kit.
8-bit Atmel
Microcontrollers
Application Note
Rev. 8394B-AVR-02/12

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2 Related items
The following list contains links to the most relevant documents, software and tools
for the Atmel AVR XMEGA-A3BU Xplained:
Atmel AVR Xplained products
Xplained is a series of small-sized and easy-to-use evaluation kits for 8- and 32-bit
AVR microcontrollers. It consists of a series of low cost MCU boards for evaluation
and demonstration of feature and capabilities of different MCU families.
Atmel Xplained USB CDC driver
The Xplained USB CDC driver file supports both 32- and 64-bit versions of Windows®
XP and Windows 7. Driver installs are not necessary on Linux®operating systems.
XMEGA-A3BU Xplained schematics
Package containing schematics, BOM, assembly drawings, 3D plots, layer plots…
AVR1923: XMEGA-A3BU Xplained Hardware Users Guide
This document.
AVR1935: XMEGA-A3BU Xplained Getting Started Guide
This application note is a getting started guide for the XMEGA-A3BU Xplained.
AVR1934: XMEGA-A3BU Xplained Software User Guide
This application note is a user guide for the XMEGA-A3BU Xplained demo software.
AVR1916: XMEGA USB DFU Boot Loaders
This application note is a user guide for the XMEGA USB DFU boot loaders.
Atmel AVR Studio®5
AVR Studio 5 is a free Atmel IDE for development of C/C++ and assembler code for
Atmel microcontrollers.
Atmel FLIP (Flexible In-system Programmer)
BatchISP (FLIP) is a command line tool for programming the flash and EEPROM
memories of the AVR and is part of the FLIP installation. It can be used to
communicate with the preprogrammed USB DFU boot loader.
Atmel JTAGICE 3
JTAGICE 3 is a mid-range development tool for Atmel 8- and 32-bit AVR
microcontrollers with on-chip debugging for source level symbolic debugging,
NanoTrace (if supported by the device) and device programming.
Atmel AVR JTAGICE mkII
AVR JTAGICE mkII is a mid-range development tool for Atmel 8- and 32-bit AVR
devices with on-chip debugging for source level symbolic debugging, NanoTrace (if
supported by the device), and device programming (superseded by JTAGICE 3).
Atmel AVR ONE!
AVR ONE! is a professional development tool for all Atmel 8- and 32-bit AVR devices
with on-chip debug capability. It is used for source level symbolic debugging, program
trace, and device programming. The AVR ONE! supports the complete development
cycle and is the fastest debugging tool offered from Atmel.
Atmel AVR Dragon™
AVR Dragon sets a new standard for low cost development tools for 8- and 32-bit
AVR devices with on-chip debug (OCD) capability.

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IAR Embedded Workbench®for Atmel AVR
IAR™ Embedded Workbench is a commercial C/C++ compiler that is available for 8-
bit AVR. There is a 30 day evaluation version as well as a 4k (code size limited) kick-
start version available from their website.

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3 General information
The Atmel AVR XMEGA-A3BU Xplained kit is intended to demonstrate the Atmel
AVR ATxmega256A3BU microcontroller. Figure 3-1 shows the available feature on
the board.
Figure 3-1. Overview of the XMEGA A3BU Xplained kit.
3.1 Preprogrammed firmware
The ATxmega256A3BU on the XMEGA-A3BU Xplained is pre-programmed with a
boot loader and a default firmware. The detailed description of the software is
available in the XMEGA-A3BU Xplained Software User Guide
(http://atmel.com/dyn/resources/prod_documents/doc8413.pdf).
3.2 Power supply
The kit needs an external power supply that can deliver 5V and up to 500mA. The
actual current requirement for the board is much less than 500mA but in order to be
able to power optional expansion boards this margin is recommended.
The power can be applied to the board either via the USB connector or on pin 10 on
the header J3. The USB connector is the preferred input because it is then possible to
connect expansion boards on top of the J3 header.
The 5V (USB supply voltage) is regulated down to 3.3V with an onboard LDO
regulator, which provides power to the entire board. Expansion top boards that
require 5V will get this from the header J3 pin 10.
3.3 Measuring the Atmel AVR XMEGA power consumption
As part of an evaluation of the ATxmega256A3BU, it can be of interest to measure its
power consumption. Because the XMEGA has a separate power plane
(VCC_MCU_P3V3) on this board it is possible to measure the current consumption

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by measuring the current that is flowing into this plane. The VCC_MCU_P3V3 plane
is connected via a jumper to the main power plane (VCC_P3V3) and by replacing the
jumper with an amperemeter it is possible to determine the current consumption. To
locate the power measurement header, please refer to Figure 3-1.
WARNING Do not power the board without having the jumper or an amperemeter
mounted since this can cause latch-up of the Atmel AVR
ATxmega256A3BU due to current flow into the I/O pins.
3.4 Programming the kit
The kit can be programmed either from an external programming tool or through an
USB boot loader which is pre-programmed on the device.
The boot loader is evoked by pushing the push button (SW0) during power-on, that is
push and hold the button and hence connect an USB cable to the kit. Programming
can be performed through the DFU programmer FLIP.
How a programmer can be connected to the kit is described in Section 4.1.

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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.

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This however will disable the JTAG interface until the connection is reestablished by,
for example soldering a bridge on the cut-strap.
4.2 I/O expansion headers
The Atmel AVR XMEGA-A3BU Xplained headers J1, J2, J3, and J4 offer access to
the I/O of the microcontroller in order to expand the board, for example by mounting a
top module onto the board.
The header J1 offers digital communication interfaces like UART, TWI and SPI. Table
4-2 shows how the Atmel AVR XMEGA is connected to the header.
NOTE When using TWI please note that no pull-ups are mounted on the board from the
factory, so it is required to either enable the internal pull-ups of the device or to mount
the external pull-ups on the available footprints (R200 and R201). Please refer to the
assembly drawing in the design documentation for the location of these footprints.
Table 4-2. Expansion header J1.
Pin on J1 Name on J1 XMEGA pin Shared with onboard functionality
1 SDA PC0 -
2 SCL PC1 -
3 RXD PC2 -
4 TXD PC3 -
5 SS PC4 -
6 MOSI PC5 -
7 MISO PC6 -
8 SCK PC7 -
9 GND - -
10 VCC_P3V3 - -
The header J2 is connected to analog ports of the XMEGA as shown in Table 4-3.
Table 4-3. Expansion header J2.
Pin on J2 Name on J2 XMEGA pin Shared with onboard functionality
1 ADC0 PB0 -
2 ADC1 PB1 -
3 ADC2 PB2 -
4 ADC3 PB3 -
5 ADC4 PA4 -
6 ADC5 PA5 -
7 ADC6 PA6 -
8 ADC7 PA7 -
9 GND - -
10 VCC_P3V3 - -
The I/O connected to the expansion header J3 is shared with on-board features as
sensors and JTAG interface. Therefore care must be taken when J3 is used for
expansions. Table 4-4 shows the mapping of the XMEGA I/O to J3.

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Table 4-4. Expansion header J3.
Pin on J3 Name on J3 XMEGA pin Shared with onboard functionality
1 PA0 PA0 Light sensor
(1)
2 PA1 PA1 Temperature sensor
(1)
3 PA2 PA2 Filter output
(1)
4 PA3 PA3 Display reset
5 PB4 PB4 JTAG TMS
6 PB5 PB5 JTAG TDI
7 PB6 PB6 JTAG TCK
8 PB7 PB7 JTAG TDO
9 GND - -
10 VCC_P5V0 - -
Note: 1. Can be disconnected from onboard functionality by cut-straps.
The header J4 offers digital communication interfaces such as UART and TWI but
care must be taken because some pins are also connected to on-board peripherals.
Table 4-5. Expansion header J4.
Pin on J4 Name on J4 XMEGA pin Shared with onboard functionality
1 SDA PE0 -
2 SCL PE1 -
3 RXD PE2 -
4 TXD PE3 -
5 SS PD0 Display register select (1)
6 MOSI PD3 Serial flash MOSI
7 MISO PD2 Display and serial flash MISO input
8 SCK PD1 Display and serial flash clock input
9 GND - -
10 VCC_P3V3 - -
Note: 1. Can be disconnected from onboard functionality by cut-strap (J204).

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5 Peripherals
5.1 Serial flash
The Atmel AVR XMEGA-A3BU Xplained has an external Atmel AVR AT45DB642D
DataFlash device mounted. A footprint is also available for adding an industrial
standard serial flash like the AT25 series from Atmel. Compatible serial flash devices
for both footprints are listed in Table 5-2 and the connection to the MCU is shown in
Table 5-1.
The footprints share the same SPI lines including the chip select, and therefore it is
not possible to mount devices on both footprints at the same time.
Table 5-1. Serial flash connection.
Pin on XMEGA Serial flash
PD1 SCK
PD3 MOSI
PD2 MISO
PF4 SS
Table 5-2. Compatible devices for the footprints.
Atmel AVR AT45DB Atmel AVR AT25DF
AT45DB64D2-CNU (mounted) AT25DF641A-SH
AT45DB321D-MWU AT25DF321A-SH
AT45DB161D-SS AT25DF161-SH
AT45DB081D-SS AT25DF081-SSH
AT45DB041D-SS AT25DF021-SSH
AT45DB021D-SS
AT45DB011D-SS
5.2 Atmel AVR QTouch button
The XMEGA-A3BU Xplained kit has one Atmel QTouch button and the connection to
the Atmel AVR XMEGA is shown in Table 5-3. The QTouch sensor, a copper fill, is
located on the second layer of the board (same as GND layer). The sensor is
shielded by the third layer (VCC layer) and therefore the sensor is not affected by any
touches from the back side of the board.
Table 5-3. QTouch button connection.
Pin on XMEGA QButton
PF6 SNS
PF7 SNSK
5.3 Battery backup system
The battery backup system backs up the RTC of the XMEGA. It consists of a coin cell
battery, a battery holder and a jumper that can be used to disconnect the battery from
the XMEGA. A manganese dioxide lithium battery (CR1220) from Panasonic with a
nominal voltage of 3V and nominal capacity of 35mAh is used in this design. In order

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to measure the backup system power consumption a header with a mounted jumper
is available. The header is shown in Figure 3-1 and is also marked with “VBAT” on
the silkscreen. The jumper can also be used to simulate battery insertion and removal
without actually removing the battery from the holder.
5.4 Mechanical buttons
Three mechanical buttons are connected to Atmel AVR XMEGA. All buttons have
external pull-ups so there is no need to activate internal pull-ups in order to use them.
When a button is pressed it will drive the I/O line to GND.
Table 5-4. Mechanical button connection.
Pin on XMEGA Silkscreen text on PCB and designator in the schematics
PE5 SW0
PF1 SW1
PF2 SW2
5.5 LEDs
There are four LEDs available on the board that can be turned on and off. Two yellow
LEDs, one green LED (power indicator LED), and one red LED (status LED). The
green and red LEDs are inside the same package and therefore the colors can be
mixed to orange when both are activated. The yellow LEDs and the red LED can be
activated by driving the connected I/O line to GND. The green LED is controlled via a
FET and is by default on when the board is powered. However, this power indicator
LED can also be turned off by driving the gate of the FET to GND.
Table 5-5. LED connections.
Pin on XMEGA LED
PR0 Yellow LED0
PR1 Yellow LED1
PD4 Red status LED
PD5 Green power indicator LED
5.6 FSTN LCD display
The NHD-C12832A1Z-FSW-FBW-3V3 is a FSTN LCD display and has a resolution of
128 x 32 pixels. In the design the display is connected via a SPI based interface.
Detailed information about the display can be obtained from the display datasheet
(NHD-C12832A1Z-FSW-FBW-3V3 from New Haven Displays) and from the display
controller datasheet (ST7565R from Sitronix).
The external circuitry of the display is configured to boost the 3.3V supply voltage by
a factor of 3 to ~10V. However, the typical supply voltage of the display (contrast
control) is 6V and therefore the boosted supply must be adjusted, and this must be
done by software when the display is configured. The following formula is used when
the voltage is adjusted by software:
REG
V
Ra
Rb
V⋅
⎟
⎠
⎞
⎜
⎝
⎛−⋅
⎟
⎠
⎞
⎜
⎝
⎛+=
162
11
0
α