Atmel XMEGA-A1 Xplained Evaluation Board ATAVRXPLAIN ATAVRXPLAIN Data Sheet
Product codes
ATAVRXPLAIN
8
AVR1010
8267B-AVR-12/10
are powered down in ACTIVE mode, just as they are in any sleep mode. These
power reduction modes will not affect power consumption in sleep.
power reduction modes will not affect power consumption in sleep.
If the CPU attempts to access a non-volatile memory with power reduction mode on,
the CPU is halted for a time interval corresponding to wake-up from IDLE sleep while
the memory is re-activated.
the CPU is halted for a time interval corresponding to wake-up from IDLE sleep while
the memory is re-activated.
NB: There is an errata regarding Flash power reduction mode and sleep. For the
affected devices, the workaround is to disable the Flash power reduction mode before
entering sleep, then enabling it again on wake-up. Power consumption in sleep is not
affected by this.
affected devices, the workaround is to disable the Flash power reduction mode before
entering sleep, then enabling it again on wake-up. Power consumption in sleep is not
affected by this.
Enable power reduction mode for EEPROM and Flash to reduce power consumption
in ACTIVE mode.
in ACTIVE mode.
2.16 Writing to EEPROM
If more than one byte is to be written to EEPROM, one should make use of the
EEPROM page buffer rather than doing byte-wise writes. This is because it takes just
as long to write one byte as it takes to write an entire page to EEPROM. If, e.g., two
bytes are to be written, byte-wise writing will take twice as long as necessary. Since
the current consumption also increases during EEPROM writing, this gives a “double
penalty”.
EEPROM page buffer rather than doing byte-wise writes. This is because it takes just
as long to write one byte as it takes to write an entire page to EEPROM. If, e.g., two
bytes are to be written, byte-wise writing will take twice as long as necessary. Since
the current consumption also increases during EEPROM writing, this gives a “double
penalty”.
To minimize power consumption, use page-wise writing to EEPROM rather than byte-
wise.
wise.
3 Code Examples
Six code examples are supplied with this application note. The main code files for
these are:
these are:
xmega_power_consumption.c
xmega_sleep_example.c
xmega_rtc32_power_consumption.c
xmega_rtc32_sleep_example.c
xplain_power_consumption.c
xplain_sleep_example.c
These are respectively meant for three different setups:
• Generic XMEGA, w/ I/O pins left floating
• XMEGA w/ battery backup system, 32-bit RTC and only 32kHz crystal connected
• XMEGA w/ battery backup system, 32-bit RTC and only 32kHz crystal connected
(e.g. A3B-family)
• Xplain evaluation board (ATxmega128A1)
The differences between these setups are the RTC driver and clock source, plus
some tweaks which are specific for the Xplain evaluation board.
The differences between these setups are the RTC driver and clock source, plus
some tweaks which are specific for the Xplain evaluation board.
For the generic setup, the ULP is used as clock source for the RTC. A 32kHz crystal
is used in the other setups. Note that the latter is mandatory for operation of the 32-bit
RTC.
is used in the other setups. Note that the latter is mandatory for operation of the 32-bit
RTC.
3.1 Power Consumption
All the
power_consumption.c
examples simply step through different sleep modes at
timed intervals. This is meant to allow for simple verification of the power