Low Power Management for CC2430 Jinho Son Real-Time System Lab

SoC solution for ZigBee Enhanced version of the 8051 Core + CC2420 RF transceiver Core 3 different model (according to flash memory size) CC2430-F32/64/128, with 32/64/128kB flash memory 8kB SRAM, 4kB with data retention in all power modes. System clock source : 16MHz RC oscillator or 32MHz crystal oscillator The 32MHz oscillator is used when radio is active. For low power operation : KHz crystal oscillator. Feature of CC2430

Power modes of CC2430 ModeoscillatorVoltage regulatorCurrent Consumption PM0 Clock oscillators onOn MCU Active (7mA) Rx mode (27mA) Tx mode, 0dbm (24.7mA) PM kHz oscillators onOn190µA PM kHz oscillators onOff0.9µA PM3 All clock oscillators offOff0.6µA power mode 1 → power mode 0 : 2µS power mode 2 or 3 → power mode 0 : 54µS

Compare of current consumption other wireless technology TechnologyTxRx(Model) Company IrDA50~100mAAgilent Bluetooth10.9mA21.8mA(STLC2500) ST ZigBee17.4mA19.7mA(CC2420) TI UWB750mA(XS110) FreeScale Wireless LAN25mA140mA(Unifi-1potable) CSR

Superframe structure IEEE MAC layer for Low-power consumption Active duration : accessible Channel Inactive duration : All devices sleep mode SD and BI are changed 15.36ms and 4min 11sec through SO(macSuperframeOrder) and BO(macBeaconOrder) ACTIVEINACTIVE beacon frame SD (Slot Duration) BI (Beacon Interval)

Data downlink IEEE MAC layer for Low-power consumption Pending address filed of beacon frame Data request frame format 512µs 320µs 192µs512µs (Short interframe spacing)

What do you do for saving the energy? Turn off unused bulb. Plug out cable of unused home appliance. Use as much water as you use. Policy for low-power consumption

Consideration of hardware design sw_control_vcc Moving detect sensor CC2430 is able to control voltage through software. We have to supply voltage to peripherals when is only using.

Sleep of MCU itself The time spent in PM0 should be as short as possible. When the radio is no used, the analog part of it can be power down. When the radio is not used, the chip can be clocked from an internal RC oscillator instead of the external 32MHz crystal. Sleep function of MCU is implemented in Z-Stack. We just have sleep time as long as possible through this function.

Dynamic control of RF level The RF output power is programmable. Downing from 0dbm to -10dbm will reduce the power consumption with more than 6mA. In a two way link the RSSI (Received Signal Strength Indicator) value can be used to dynamically adjust the output power.

Executing program code from RAM instead of Flash Instead of reading from flash, executing program code from RAM will reduce the power consumption. In applications where the CPU continually runs a small loop/piece of code.

Autonomous data transmission in compliance with environment Data size Transmission frequency Fire Alarm systemGreenhouse management system Temperature sensor Smog sensor Flame sensor Temperature sensor Humidity sensor To detect rapidly when a fire broke outManage to growing a plant in greenhouse Sensor node have to be control autonomous data transmission in compliance with environment

Control sleep modes in Z-Stack Sleep enabled by the POWER_SAVING compile option ZDO node descriptor indicates “RX is off when idle”. This is done by setting RFD_RCVC_ALWAYS_ON = FALSE to FLASH in f8wConfig.cfg Z-Stack tasks have no scheduled activity The MAC has no scheduled activity All Z-Stack tasks “agree” to permit power savings

Routine for saving power in Z-Stack call

halSleep( ) function Perform the sequence of shutting down the MAC, turning off peripherals, entering the sleep mode Waking up the MCU after sleep, turning on peripherals, finally restarting the MAC. Since the Z-Stack OSAL loop runs independently of the MAC scheduler, Z-Stack does not know the processing state of the MAC. The call to MAC_PwrOffReq() will request a MAC shutdown.

Target board for sleep test Potentiometer: 0.33mA Light sensor: 0.015mA LED: 24mA Accelerometer: 1mA USB MCU Remove external peripheral device to reduce leakage current

Result up to now Battery mode Sleep Non-sleep Per 5sec Battery mode Non-sleep