Atmel AVR1019 Installation and operating instructions

Atmel AVR1019: Migration from
ATxmega128A1/64A1 to ATxmega1281U/64A1U
Features
• Enhancements and added functions
• Reset sources
• I/O ports
• DAC – digital to analog converter
• AC – analog comparator
1 Introduction
This application note is a guide to assist users of ATxmega128A1/64A1 in
converting designs to Atmel ATxmega128A1U/64A1U. For complete device details,
always refer to the most recent version of the ATxmega128A1U/64A1U datasheet
and the Atmel®AVR®XMEGA®AU manual. Errata differences between
ATxmega128A1/64A1 and ATxmega128A1U/64A1U are not listed in this
document, only in the device datasheet.
In addition to the differences described in this document, other typical
characteristics could be different. Please check the latest datasheet for details.
ATxmega128A1U/64A1U also includes new configuration options and functions. As
far as possible these are implemented as a superset of existing
ATxmega128A1/64A1 functions, so existing code for these devices will work on the
new devices without changing existing configuration or enabling new functions. The
new options and functions are listed in the application note for customers who in
addition to a pure migration also wish to see an overview to consider use of the
new functions.
8-bit Atmel
Microcontrollers
Application Note
Rev. 8415A-AVR-07/11

2 Atmel AVR1019 8415A-AVR-07/11
2 Enhancements and added functions
In this section, we summarize the enhancements or added features in Atmel
ATxmega128A1U/64A1U compared with Atmel ATxmega128A1/64A1. For pure
migration, you can skip the section and start from the next section.
2.1 USB
•One USB 2.0 full speed (12Mbps) and low speed (1.5Mbps) device compliant
interface is added
2.2 Clock system
•A divide-by-two option for the PLL output that enables output frequency down to
10MHz
•PLL lock failure detection with optionally Non-Maskable Interrupt (NMI), for
improved safety and robustness
•Non-prescaled Real Time Counter clock source options: External clock from
TOSC1, 32.768kHz from TOSC, and the 32.768kHz from the 32.768kHz Internal
Oscillator
•The 32MHz Internal Oscillator can be tuned to run at any frequency between
30MHz and 55MHz
2.3 I/O ports
•Alternate pin locations for Timer/Counter 0 Compare Channels, USART0 and SPI
•Alternate pin locations for the Peripheral Clock and Event output functions
2.4 Analog to digital converter
•Automatic input channel scan
•VCC/2 voltage reference option
•1/2x (divide by two) gain stage setting
•Internal ground can be used as negative input in differential mode (with gain)
2.5 Analog comparator
•A constant current source
2.6 CRC16/CRC32 generator
•A CRC16/CRC32 Generator Module that supports CRC16 (RC-CCITT) and CRC-
32 (IEEE 802.3)
2.7 16-bit timer/counter0
•Split mode that enable two 8-bit Timer/Counters with 4PWM channels each
2.8 High resolution extension
•Hi-Res+ option to allow PWM resolution to be increased with 8x (3-bit)

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8415A-AVR-07/11
2.9 Power management
•Possibility to enable sequential start of the components used for analog modules
ADC and Analog Comparator in order to reduce start-up current

4 Atmel AVR1019 8415A-AVR-07/11
3 Reset sources
3.1 Brown-out detection
The programmable BODLEVEL settings are different in Atmel
ATxmega128A1U/64A1U. See Table 3-1 below for details. Please refer to the device
datasheet regarding tolerance for the Brown-out levels.
Table 3-1. Brown-out levels.
BODLEVEL VBOT – XMEGA AU VBOT – XMEGA A
111 1.6V 1.6V
110 1.8V 1.9V
101 2.0V 2.1V
011 2.4V 2.6V
010 2.6V 2.9V
000 3.0V 3.4V

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4 I/O ports
The I/O port pins are LVTTL and LVCMOS compatible for Atmel
ATxmega128A1U/64A1U devices. The minimum “Input High Voltage” is never higher
than 2.0V for VCC > 2.7V.
In Atmel ATxmega128A1/64A1, the minimum “Input High Voltage” is 0.7VCC, and
could be higher than 2.0V for VCC>2.86V.

6 Atmel AVR1019 8415A-AVR-07/11
5 DAC – digital to analog converter
The Atmel ATxmega128A1U/64A1U DAC has two continuous output channels, and
not a sample and hold circuit as Atmel ATxmega128A1/64A1 devices. This gives
continuous time output and higher sample rate for each channel. There is separate
calibration (offset/gain) for each DAC channel in ATxmega128A1U/64A1U.
When DACA0OFFCAL (in Production Signature Row) is written to CH0OFFSETCAL
in DACA, CH1OFFSETCAL is also written with this value. The details of this
operation are shown below.
The first step,
•read DACA0OFFCAL from production signature row
•write DACA0OFFCAL to DACA.CH0OFFSETCAL
This will result in:
•DACA.CH0OFFSETCAL = DACA0OFFCAL
•DACA.CH1OFFSETCAL = DACA0OFFCAL
The second step,
•read DACA1OFFCAL from production signature row
•write DACA1OFFCAL to DACA.CH1OFFSETCAL
This will result in:
•DACA.CH1OFFSETCAL = DACA1OFFCAL
After that, any further writing to DACA.CH0OFFSELCAL does not change
DACA.CH1OFFSELCAL until the next reset. The same is implemented for both
OFFSET and GAIN calibration registers in DACA and DACB. This ensure that
customers using the ATxmega128A1/64A1 DAC can continue and use the same
calibration sequence and still calibrate both channels.
TIMCTRL register does not exist in ATxmega128A1U/64A1U, so there are no timing
constraints on DAC operation.

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6 AC – analog comparator
In Atmel ATxmega128A1U/64A1U, there is a two-cycle delay from writing a new MUX
setting until it takes effect.

8 Atmel AVR1019 8415A-AVR-07/11
7 Registers
7.1 Removed registers and bits
The below table lists register bits, which exist in Atmel ATxmega128A1/64A1 but not
in Atmel ATxmega128A1U/64A1U.
Table 7-1. Register bits and functionality that does not exist in
ATxmega128A1U/64A1U.
Register name Register bit Function
FUSEBYTE2 BODACT[1:0](1) BOD functionality when in active mode
CONINTVAL[2:0] DAC Conversion Interval
TIMCTRL REFRESH[3:0] DAC Channel Refresh Timing Control
Note: 1. BODACT fuses are now located in FUSEBYTE5 for all devices.

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8 Table of contents Features...............................................................................................1
1 Introduction......................................................................................1
2 Enhancements and added functions .............................................2
2.1 USB.....................................................................................................................2
2.2 Clock system.......................................................................................................2
2.3 I/O ports...............................................................................................................2
2.4 Analog to digital converter...................................................................................2
2.5 Analog comparator..............................................................................................2
2.6 CRC16/CRC32 generator ...................................................................................2
2.7 16-bit timer/counter0 ...........................................................................................2
2.8 High resolution extension....................................................................................2
2.9 Power management............................................................................................3
3 Reset sources ..................................................................................4
3.1 Brown-out detection ............................................................................................4
4 I/O ports............................................................................................5
5 DAC – digital to analog converter ..................................................6
6 AC – analog comparator..................................................................7
7 Registers...........................................................................................8
7.1 Removed registers and bits.................................................................................8
8 Table of contents .............................................................................9

8415A-AVR-07/11
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