Atmel AVR1923

9

8394B-AVR-02/12

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