The primary application for QuickLogic’s EOS S3 Ultra-Low Power Voice and Sensor Platform is mobile, battery-powered devices that require both always-on wake word detection and extended battery life. As recently as a year ago, if anyone told me there would be a compelling use-case for wall powered devices I wouldn’t have believed it, or at least been very skeptical. Power usually isn’t a major concern for designers when there’s a 110-240V supply available. The top priority by far is performance. However, the relatively new One-Watt Initiative is changing that.
The One-Watt Initiative (per it’s wiki page) is an energy-saving initiative by the International Energy Agency (IEA) to reduce standby power-use by any consumer appliance, i.e. TVs, microwaves, etc., to not more than one watt in 2010, and reduced further to 500 mWatt in 2013, which has given rise to regulations in many countries and regions. These are large markets too. Worldwide shipments for Smart TVs are estimated at 265 million units in 2019, and smart connected white-goods to 223 million units a year by 2020.
In addition to being good news for the planet, there’s a few reasons this is important. First, many of the appliances affected by the initiative are moving towards voice control. We’ve seen this trend steadily growing in popularity each CES, and expect more of it this year. Second, it may not have been the case in past decades, but power consumption now matters for these manufacturers. Getting that Energy Star rating means something. On the shelves in Europe, it’s common for retail stores to list the power ratings of appliances above the feature list and price. energy efficiency gets the top billing! Lastly, hitting that 500 mWatt number is a challenge for most appliances even before adding voice recognition.
The 500 mWatt goal gets even more difficult when you take into consideration these appliances need far-field voice support, i.e. be able to hear a human speaker 12 to 15 feet away from the device. This requires a multi-microphone array (typically 3 – 7 microphones), significant CPU MIPS, and the excess power consumption to go along with it. By comparison, Close-Talk voice (up to 0.3 meters), used for mobile hearable and wearable devices, can operate with one or two mics at an average power consumption under 1 mWatt.
So, if a Smart TV or Appliance wants far-field voice recognition, and initiative compliance, there’s a challenge at hand. A solution is needed that can provide far-field performance, but at power levels associated with Close-Talk.
One approach is to employ an architecture that can operate in two modes. For example, while the appliance is on, and there’s no 500 mWatt limit, have an Apps CPU run in “high-performance” mode supporting far-field voice. When in standby, keep the Apps CPU asleep, and use a dedicated low-power MCU to listen for a wake word command in the “low power” mode, and once detected, wake Apps CPU to process the subsequent utterance.
The S3’s ultra-low power wake word functionality and flexible eFPGA block makes it ideal for the MCU role. For the high-performance mode its eFPGA can interface with multiple digital microphones and reformat the audio data as required by the Apps CPU’s I2S or SPI ports. For low-power mode, the S3 listens for the wake-word (at well under one milli-watt) then quickly transitions into the high-performance mode by waking the Apps CPU and buffering mic data until it’s ready.
So, due to the One-Watt Initiative, both performance AND power are now significant considerations for designers of voice controlled Smart TV and Home Appliances. CES should provide more than a few examples of the trend this year and the EOS S3 platform is a uniquely suited fit.