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ATmega128RFA1. Power Measurement. ATmega128RFA1. SoC ( uC and Transceiver) Up to 16 MHz (i.e. almost 16 MIPS) Voltage range: 1.8v to 3.6v 16K bytes RAM 128 K Flash Zigbee compliant transceiver. ATmega128RFA1. Transceiver TX Power up to 3.5 dBm (2.24 mW )
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ATmega128RFA1 Power Measurement
ATmega128RFA1 • SoC (uC and Transceiver) • Up to 16 MHz (i.e. almost 16 MIPS) • Voltage range: 1.8v to 3.6v • 16K bytes RAM • 128 K Flash • Zigbee compliant transceiver
ATmega128RFA1 • Transceiver • TX Power up to 3.5 dBm (2.24 mW) • Speed -> 250 kb/s and 500 kb/s, 1 Mb/s, 2 Mb/s • Security -> AES (128 bits) • RX current -> 12.5 mA • TX current -> 14.5 mA (max output power)
Power Control Features • Power Reduction Registers • PRR0 (TWI, Timers, etc) • PRR1 (one bit to shutdown transceiver) • PRR2 (for disabling the four SRAM blocks) • Watchdog Timer • Brown-Out detect (BOD)
Important Peripherals • Timers • ADC • TWI (I2C) -> RTC wake up • WDT (wakeup or reliability enhancement) • Transceiver
Sleep Current • Power down mode (deep sleep) • All peripherals disabled • PRR0 = 0xFF • PRR1 = 0xFF • WDT enabled Current = 800 nA
Sense & Send: Cycle Time 3.44 ms
Sense & Send: TX Time 1.68 ms
Sense & Send: Sense Current 4.2 mA
Sense & Send: TX Current 15.6 mA
Life Time Estimate • Ampere Hour • Sense -> 2.05 x 10-6mAH • Tx -> 7.28 x 10-6mAH • Total (sense & send) -> 9.33 x 10-6mAH • In ‘one hour’ • # of Tx -> 450 • Sense & Send -> 4.1985 x 10-3mAH • Sleep -> 2.88 x 10-6mAH • Total (sense, send & sleep) -> 4.2 x 10-3mAH
Life Time Estimate • For a battery of 200 mAH • # of hours we get is 200/4.2 x 10-3 i.e. 47619 hrs or about 5 years
Additional Possible Optimization • Frequency scaling • Static • Dynamic • Use of Real-Time Clock • Keep watchdog timer disabled in sleep mode • RTC chip takes less current than the WDT • Wake up on RTC alarm interrupt • More flexible (not just max of 8 sec)