Atmel XMEGA-A1 Xplained Evaluation Board ATAVRXPLAIN ATAVRXPLAIN Hoja De Datos

 

8267B-AVR-12/10 

Table 2-1: Available sleep modes for XMEGA. 

The three most commonly used modes are IDLE, POWER-SAVE and 
POWER-DOWN: 

•  In IDLE, most peripherals are still operating – only the Atmel

®

 AVR

®

 CPU core and 

non-volatile memories (Flash and EEPROM) are stopped. The DMA controller and 
Event system are still active in this mode, allowing for e.g. AD conversions and 
transfers via the USART to continue, even though the CPU is not operating. The 
device can be woken up by all interrupts. 

•  In POWER-SAVE, the low frequency Real Time Clock (RTC) timer is still running 

while the CPU and most other peripherals are stopped. The RTC is commonly 
used to wake the device up at timed intervals. Because the system clock source is 
stopped in this sleep mode, wake-up takes a bit longer than for IDLE since the 
system clock must stabilize before operation. 

•  POWER-DOWN is the deepest sleep mode. In this mode most of the device 

peripherals are stopped. The device is unable to wake itself up from this mode 
since both the peripheral clock and RTC are disabled. This mode therefore relies 
on external input, e.g. asynchronous pin interrupts or TWI, to wake the device up. 
There are exceptions to this rule: XMEGAs with the battery backup module and 
32-bit RTC. The RTC in these devices will run regardless of the sleep-mode. 

The XMEGA family also supports two additional sleep-modes which are useful when 
a short wake-up time is needed: 

•  STANDBY, which is POWER-DOWN with system clock source still running. 
•  EXTENDED STANDBY, which is POWER-SAVE with system clock source still 

running. 

These two sleep-modes do not give as low power consumption as POWER-DOWN 
and POWER-SAVE respectively, but are useful if fast response is vital to the 
application. 

Note that asynchronous port interrupts and TWI address matches can wake the 
device up from all sleep modes. Refer to the device manual for further information 
about these sleep modes and operation of them.