AVR®530: Migrating from AT90USB162/82 to

AVR®530: Migrating from AT90USB162/82 to
ATmega16U2/8U2
8-bit
Microcontrollers
1 Introduction
Application Note
In order to optimize the manufacturing process and to further reduce current
consumption, an optimized version of AT90USB162/82 has been introduced.
The ATmega16U2/8U2 is a functionally identical, drop-in replacement for the
AT90USB162/82. All devices are subject to the same qualification process and
same set of production tests but since the manufacturing process is not the same,
some electrical characteristics differ. In addition, the performance of some analog
modules such as the Brown-Out Detector (BOD) and Power-On Rest (POR) has
been improved. Some new features have also been added to the
ATmega16U2/8U2.
AT90USB162/82 and ATmega16U2/8U2 have separate datasheets. This
application note aims to outline the differences between the two devices and their
datasheets, but there is also a detailed change log to assist the user at the end of
the ATmega16U2/8U2 datasheet. Remember to always use the latest revision of
the device datasheet.
Minor differences in typical characteristics are not discussed in this document as
long as the low and high limits remain the same. For detailed information about the
typical characteristics, see sections “Electrical Characteristics” and “Typical
Characteristics” of the device datasheets.
Note: This application note serves as a guide to ease migration. For complete
device details, always refer to the most recent version of the
ATmega16U2/8U2 datasheet.
Rev. 8224A-AVR-06/09
2 Changes in Characteristics
This section outlines such differences in characteristics that may have an effect on
the application in which the device is used. For detailed information, refer to the most
recent version of the device datasheets.
2.1 I/O-Ports Input Characteristics
All I/O-Ports Input trigger are now LVTLL compatible for ATmega16U2/8U2 (only
MOSI and MISO pins in AT90USB162/82). See VIL/VIH Electrical parameters for
standards IOs in ATmega16U2/8U2 datasheet.
2.2 Reset
Table 2-1 summarizes the differences between the reset circuitry of AT90USB162/82
and ATmega16U2/8U2.
Table 2-1. Power-On Reset
AT90USB162/82
Symbol
2
ATmega16U2/8U2
Unit
Min
Typ
Max
Min
Typ
Max
VPOR
-
1.2
-
1.1
1.4
1.6
V
VPOA
-
1.1
-
0.6
1.3
1.6
V
SRON
-
-
-
0.01
-
-
V/ms
AVR530
8224A-AVR-06/09
AVR530
3 New Bits and Registers
This section summarizes the functional improvement added to the new devices. For
more details on the functional enhancements, see ATmega16U2/8U2 datasheet
3.1 Watchdog timer
The watchdog timer has been improved to support more clock timer divider
configurations. Table 3-1 lists the register and bits that have been added to the device
as a result of functional enhancements. In AT90USB162/82 these bits and register
were marked as reserved.
Refer to ATmega16U2/8U2 datasheet for the complete explanation of these bits.
Table 3-1. New Bits for Watchdog timer
Addr.
Name
0x62
WDTCKD
Bit 7
Bit 6
-
-
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
WDEWI
WCLKD
WDEWI
WDEWI
WCLKD
WCLKD
FCM
2
F
E
1
0
3.2 Analog comparator
Analog comparator has been improved so that the AT90USB162/82 now supports 7
analog inputs. In Table 3-2 are listed registers and bits that have been added to the
device as a result of functional enhancements. In AT90USB162/82 these bits and
registers were marked as reserved.
Refer to ATmega16U2/8U2 datasheet for the complete explanation of these bits.
Table 3-2. New Bits and Register for Analog Comparator
Addr.
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0x7D
ACMUX
-
-
-
-
-
CMUX2
CMUX1
CMUX0
4 Summary of Changes
For a summary of changes, see the revision history at the end of the
ATmega16U2/8U2 datasheet.
3
8224A-AVR-06/09
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8224A-AVR-06/09