Ember uses ARM core for ZigBee SoC

Bob LeFort, Ember's ceo, said utility companies were taking a lead in the move. "They want to build products which last. They want a high level of security and robustness. But they want these features at a reasonable price." The response is the EM300 series, based on ARM's Cortex-M3 core. Two devices are available initially: the EM351 and 357. According to LeFort, the 351 is 'ideal' for small applications, such as light switches, while the 357 is targeted at more complex applications, such as room thermostats. Nick Horne, the company's director of ic engineering, said the devices were integrated SoCs, with flash and ram complementing the ARM core. "It's a major upgrade," he claimed, "with the most obvious improvement being the ARM core." The Cortex-M3 was selected for its core performance/code density ratio. "Although 32bit processing is not important in itself," Horne continued, "the M3's processing power is a key driver." The part also sees a boost of 6dB in its free space rf power, doubling the existing range. Horne says this does away with the need to use an external power amp. Power consumption is also important and the 300 series brings a 25% increase in battery life. One contributory factor is a deep sleep mode, in which consumption drops to less than 1µA. "Even so," Horne noted, "this mode represents 50% of power consumption." Despite launching into a price sensitive market, LeFort says the $3 price tag for the parts is 'good'. "These are not consumer products," he pointed out. "They are aimed at sophisticated systems." But he admitted the price will need to drop to less than $1 'over time'.