Xin Yang

Overview

With two products out on the market and the largest pet tracker subscriber base, Whistle is the market leader of pet wearables.  

Products

At Whistle, I am involved with two main products.  First, the Activity Monitor is a "Fitbit" for dogs that classifies activity between walking, playing, and resting.  Second, the GPS Tracker is a battery powered wearable integrating GPS, Cellular, and a Sub Gig radio.  

My Role

As firmware manager, I help design, architect, and contribute to the code base.  I lead code and design reviews, and as well as algorithmic improvements for Firmware related issues.

Overview

Crestron Electronics is the market leader for high end home automation and hotel management products.  The lighting group has created an entire product line of both wired and wireless devices designed for controlling home, office, and hotel spaces.  All Crestron products are connected to a sophisticated control system where a programer can write in C# to customize the behavior and interaction of every smart device. 

My Role

As the Firmware Manager for both lighting and shade products, I have been responsible from the initial inception to the final release of over a dozen products.  My duties during the product release cycle starts at developing clear and concise firmware specifications from marketing requirement while reviewing hardware designs to progress tracking and then finally onto QA, production and customer support.  Although I've always ensured that my Engineers are the main drivers of each project, I have never shied away from taking a more hands on role when necessary.  I've created prototypes when hardware was not yet available, reviewed code and Zigbee protocol when customer or design issues come up, and often goes into the field to diagnose and solve difficult customer problems. 

Products

I've included a selection of recently released products that I've been involved with.  Most common products include: wired and wireless battery button panels and dimmers, door locks, and RF remotes. 

Overview

Sensing is an important part of controlling a smart home.  Knowing which areas are currently occupied isn't only good for reducing energy usage but also for enabling better automation and seamless control of a smart home.

Products

There are two variants of occupancy sensors.  One is a wireless battery version that uses only passive infrared and the other is wired and has both passive infrared and ultrasonic sensors.  

In addition to occupancy sensing, we've also developed a wireless battery photo sensor that monitors room light level in order to control dimming so that the overall amount of light in the room is always fixed as the amount of sunlight changes.

My Role

As firmware manager, I lead efforts in defining product features and translating these features to actionable engineering requirements.  On new products such as the closed loop photo sensor, there is not much institutional knowledge so i also helped create initial prototypes and control algorithms.

Overview

Air conditioning and heating is another major part of an automated smart home.  Part of the challenge is building an universal enough product that can function in a wide variety of HVAC setups found not only in homes but also in hotels and large commercial spaces.

Product

Crestron makes 2 major families of thermostats.  One is wireless and battery powered that power steals when available.  The other types are wired with optional PIR occupancy sensors. 

My Role

As firmware manager, I helped shape and resolve wireless protocol issues with the sleepy behavior of the wireless thermostat.  In addition, I helped create and define the behavior of the first wired PIR thermostat designed for hotel and general hospitality applicaitons.

Overview

Shading has been one of the faster growing product segments offered by Crestron.  Though initially the mechanicals including the motor, gear train and the BLDC drive algorithm was outsourced, recent shade products designs have been completely done in house.

Product

In addition to shade motors in different sizes and lifting abilities, we've also created a power supply hub product that is capable of diagnosing issues and helping the installers with the installation process.

My Role

As firmware manager I help track the research process of the BLDC drive algorithm to achieve better efficiency with lower output noise.  Novel drive algorithms and approaches were developed to address very particular engineering challenges.  On the power hub, I helped define the functional behavior and shepherded the product from engineering through production.

Overview

FedEx wanted to expand their shipping services by incorporating sensing into their supply chain.  In particular, they were looking to guarantee the condition of packages as it transited through the delivery system.  This allowed customers who shipped high value or temperature and shock sensitive products such as pharmaceuticals to ensure the condition of their products through the delivery process.

Product

The Sense Aware asset tracker is a battery powered sensing device that reports environmental conditions and position through a cellular link.  The sensor monitors basic environmental conditions such as light, humidity and temperature and as well as physical shock.  In addition, because packages are often shipped by air, an advanced inertial algorithm processed the integrated gyroscope and accelerometer data to detect takeoffs and landings so that the cellular radio can be put in airplane mode during the flight.

My Role

As the senior engineer on the project I was responsible for the design and implementation of all firmware.  The architecture was split between 2 processors.  A low power 8 Bit microprocessor managed the sensors, alert thresholds, and passed the data to the main processor when necessary.  The main processor was an ARM9 that supported J2ME.  The main processor ran the inertial flight detection algorithm and the messaging protocol that sent the data to the back end server though the cellular connection.

Overview

Magnetic compasses are inaccurate, sensitive to interference from ferrous metals, and require recalibration.  Under a research grant from the DOD, we were tasked with researching and developing an extremely accurate man portable gyroscope based compass that would fit on a set of binoculars.  The principle behind using gyroscopes to find north is based on the ability to detect the rotation of the earth.  The better the gyroscope is able to detect the earth rotation, the better it is able to determine how well the compass is aligned with the earth's axis of rotation and hence better north finding.  Since the earth rotates very slowly, the challenge lies in detecting that very faint motion with the best gyroscopes possible.

Product

Due to form factor and power constraints, we used multiple high precision MEMS gyroscopes mounted on a rotating platform that spun exactly 180 degrees (see first image).  All sensors were interfaced to an custom FPGA which processed the raw data samples and forwarded to the OMAP processor with ARM and DSP cores.

My Role

As the lead Firmware Engineer, I was responsible for bringing up the Free RTOS environment on the OMAP board.  I wrote the I2C,SPI, and Motor controller drivers.  I also specified the sensor requirement to the FPGA designer and worked with him to debug the timing and logic.  In addition to platform support, I also developed the closed loop control software that ran the gyroscope and helped the sensor designers meet their performance goals.

Overview

As a researcher for UC Berekely, I was involved in a project where architects needed engineering help in building and designing wireless smart sensors for smart buildings and homes.  They needed hardware that monitored power consumption at the outlet level and at the circuit breaker level.  Firmware was needed to drive the 15.4 radios and meshed the data back to a gateway.  A small production run was needed at the end to furnish a couple of test homes.

Product

Two different devices were developed to meet the outlet level and house level monitoring needs.  The outlet current monitor consists of a Hall Effect sensor tied to a TI custom metering IC that reported current, power factor, and various AC mains related metrics.  The power monitoring IC interfaced to a wireless processor module (ATMEGA+CC1000) that periodical sent the meter data to the gateway.

The house meter used a similar architecture but with different sensors. The wireless processor module was a MSP430 paired with a CC2420. The processor communicated to the meter over Modbus.

My Role

I was solely responsible for all aspects of the hardware design, layout, mechanical, and firmware development.  

Overview

Environmental sensing is a great fit for wireless sensor network technology. The development of the Eko product was motivated by vineyards that needed an easier way to monitor the soil condition of their prized grape vines and the soil moisture sensor was developed to help maintain and reduce water usage for expensive golf course greens.

Product

The Eko environmental sensor was a wireless and solar powered device that could run indefinitely given a couple of hours of sun light a day.  The device plugged into a variety of environmental sensors that helped farmers grow better grapes which produced better wine in Napa Valley.

The ground moisture sensor was a completely buried moisture monitor that continuously reported the condition of the soil.  To power through several inches of wet earth, the radio puts out over a Watt of RF energy.  To stay FCC compliant at these high energy levels, the sensor was a frequency hopper.  And in order to run on a single set of batteries for 10 years, the sensors only communicated when sending data or maintaining synchronization with the hopping network.  However even at a Watt, when buried in soil, each node is unable to reach the gateway directly.  Instead, every soil sensor relies on a set of above ground nodes to help mesh the data back to the gateway. 

My Role

As the firmware engineer, I developed the low power wireless mesh protocol for the eKo product.  Although it was solar powered, it still had to be very efficient when using the radio.  For the soil moisture sensor, I extended the low power protocol to frequency hop while supporting a network that had a mixture of routers and end devices.

Overview

Low power processor and radio modules by themselves are often not sufficient to run on batteries alone.  The underlying communication protocol is an important part of designing wireless networked products that lasts multiple years on batteries.

Product

As a module maker, Crossbow Technologies created a series of radio processor modules that were both sold independently and integrated into complete products.  To enable customers to create battery powered applications based on these platforms, a low power protocol was needed that also allowed all the nodes to self form in a mesh and route data.

My Role

As the engineering lead on all MAC layer development, I created the low power stack for FSK byte radios such as the CC1000 and for 802.15.4 packet radios such as the CC2420 and the RF230.  I also did platform ports for various processors from families that include thed ATMEGA and MSP lines.