RC220x

©2005 Radiocrafts AS

RC220x Data Sheet (rev. 1.0)

Page 9 of 17

Power Management

The ZigBee protocol allows End Devices to be powered down, while Routers must be

powered all the time in order to handle packet routing. Battery operated devices should be

End Devices in order to reduce the power consumption to a minimum.

The module can be set in several sleep modes using the features of the MCU and turning off

the RF transceiver. Sleep modes enable the application to shut down unused modules in the

MCU, thereby saving power. The MCU provides various sleep modes allowing the user to

tailor the power consumption to the application’s requirements. To enter any of the six sleep

modes available in the ATmega128L/64L/325, the SE bit in MCUCR must be written to logic

one and a SLEEP instruction must be executed. The SM2, SM1, and SM0 bits in the MCUCR

Register select which sleep mode (Idle, ADC Noise Reduction, Power-down, Power-save,

Standby, or Extended Standby) will be activated by the SLEEP instruction. For further

information on using the various sleep modes, please refer to the respective MCU data

sheets.

In applications like switch remote controls, the switch buttons should be connected to one of

the interrupt pins. PIR sensors (for occupancy detection) and light sensors should also be

using pin interrupts to awake the device from power down mode (PD). During PD the pin

interrupts are still active.

Temperature sensors, humidity sensors and similar could be polled at regular intervals using

the 32 kHz low frequency oscillator timer to awake the device. In this case using the Idle

mode with 32 kHz oscillator is recommended. This mode is not available for RC2202.

In order to ensure that the internal Power On Reset (POR) operates correctly, the maximum

rise-time specification for VCC must be met (see Electrical Specifications). If longer rise-time

is expected it is recommended to use an external POR circuit attached to the RESET pin (see

Application Note AN001). Slow VCC rise-time or short power interruptions may cause

improper operation that is not handled by the internal POR. In this case the RESET should

be activated in order to ensure proper start-up.