Atmel Xplained Evaluation Board ATXMEGAA3BU-XPLD ATXMEGAA3BU-XPLD データシート
製品コード
ATXMEGAA3BU-XPLD
6
AVR1934
8413A-AVR-09/11
2.5 Battery backed Real Time Counter
The Atmel AVR XMEGA-A3BU features battery backup system support, which can be
used to power an ultra low-power 32-bit Real Time Counter (RTC), and a 32.768kHz
crystal oscillator, providing a 1Hz clock to the RTC. On the XMEGA A3BU Xplained
board the RTC is powered by a button cell battery.
used to power an ultra low-power 32-bit Real Time Counter (RTC), and a 32.768kHz
crystal oscillator, providing a 1Hz clock to the RTC. On the XMEGA A3BU Xplained
board the RTC is powered by a button cell battery.
The battery is connected to the battery backup systems V
BAT
pin, ensuring power to
the RTC when the main power is disconnected, allowing the storage of current time
on the board. Typical power consumption with the RTC running is 500nA.
on the board. Typical power consumption with the RTC running is 500nA.
During production of the XMEGA-A3BU Xplained board, the production time is stored
in the user signature row, and the RTC is initialized to the current time in UTC
(Coordinated Universal Time), allowing the demo application to show the time relative
to the time zone, and time elapsed since production.
in the user signature row, and the RTC is initialized to the current time in UTC
(Coordinated Universal Time), allowing the demo application to show the time relative
to the time zone, and time elapsed since production.
2.5.1 Usage in demo application
The data from the RTC is used in the calculation of current date and time in the
Date/Time and Production date applications. This is done by interfacing the XMEGA
RTC32 driver (
Date/Time and Production date applications. This is done by interfacing the XMEGA
RTC32 driver (
rtc32.c
and
rtc32.h
), and reading the counter register.
The main demo application verifies that the RTC is not running on battery power
before trying to initialize it. If the V
before trying to initialize it. If the V
BAT
system check fails, the RTC is not running, and
must be reinitialized. The applications will also try to verify that the RTC has not been
reset by comparing it to the production time stored in the user signature row. If by
chance the RTC register is cleared, such as when the backup battery is removed, the
current time will be reset to whichever is later, one second after the production time
stored in the user signature row, or 01.01.2011 00:00:00 UTC, allowing for correct
operation of the demo application.
reset by comparing it to the production time stored in the user signature row. If by
chance the RTC register is cleared, such as when the backup battery is removed, the
current time will be reset to whichever is later, one second after the production time
stored in the user signature row, or 01.01.2011 00:00:00 UTC, allowing for correct
operation of the demo application.
2.6 Monochrome Graphics System (gfx_mono)
The monochrome graphics library gfx_mono provides functions for a high level
interface for drawing primitives, pixel manipulation and writing text to LCD panels. In
this configuration, it is set up to interface the ST7565R LCD controller, which in turn
interfaces the C12832_A1Z LCD panel. It is created so that it provides a complete
abstraction layer on top of the LCD controller interface, allowing for easy porting to
other LCD controllers and panels. All ST7565R and C12832_A1Z specific functions
are located in
interface for drawing primitives, pixel manipulation and writing text to LCD panels. In
this configuration, it is set up to interface the ST7565R LCD controller, which in turn
interfaces the C12832_A1Z LCD panel. It is created so that it provides a complete
abstraction layer on top of the LCD controller interface, allowing for easy porting to
other LCD controllers and panels. All ST7565R and C12832_A1Z specific functions
are located in
gfx_mono_c12832_a1z.c
and
gfx_mono_c12832_a1z.h
.
The library allows for drawing and filling of primitives (lines, rectangles, circles) using
gfx_mono_generic.h
, and text printing using
gfx_mono_text.c
and
gfx_mono_text.h
. The former also allows drawing of bitmaps to the graphic memory.
The library supports writing to a frame buffer for easy manipulation of pixel data, in
case the LCD does not support pixel data reads. As the LCD controller serial interface
chosen for this board does not allow for reading of pixel data, a frame buffer is
utilized.
case the LCD does not support pixel data reads. As the LCD controller serial interface
chosen for this board does not allow for reading of pixel data, a frame buffer is
utilized.
2.6.1 Primitives drawing
The library allows drawing of certain primitives, such as lines, rectangles and circles,
defined in gfx_mono_generic.h. These functions are used in the demo applications
menu system, and button splash screen. The drawing of primitives is handled by the
library, but there is also support for hardware based primitives, given support for this
in the controller. Primitives are handled by the library on this board.
defined in gfx_mono_generic.h. These functions are used in the demo applications
menu system, and button splash screen. The drawing of primitives is handled by the
library, but there is also support for hardware based primitives, given support for this
in the controller. Primitives are handled by the library on this board.