Ansian Semiconductor has recently acquired Fairchild semiconductor to bring customers 50 years of experience in automotive industry, which is the world's second largest non-microcontroller automotive semiconductor supplier, providing comprehensive programs for automatic driving and automotive functional electronics. Sensor is especially critical in the process of fasting into intelligence. Under this trend, Mesos Semiconductors launched a smart sensor in the world's first passive, no additional microcontroller control, based on RFID protocol, single-chip integration energy transceiver function, detecting temperature, humidity, pressure, and distance, creating sensor applications New pattern.
Function module and working principle of intelligent passive sensors
Intelligent passive sensors include three functional modules: antenna module, sensor module based on Magnus IC, power, single chip, processing module, shown in Figure 1. The antenna module is based on the UHF industry standard second edition protocol for wireless communication and collect energy for internal processing units. Power, single-chip, processing module is compatible with RFID ecosystem components, and can be read with standard RFID readers. Based on MAGUS IC (industry first passive RFID sensor chip), adjustable front-end automatic tuning modules can detect environmental status, such as humidity or pressure, each with humidity or pressure, each with a humidity or pressure, each with a separate temperature. The sensor is read at the temperature information, and the chip detects the distance / motion / state by wireless signal intensity, and each smart sensor is stored inside the store to save unique IDs for identification. The final detection accuracy depends on the sampling frequency in the UHF RFID operating frequency range.
Figure 1: Intelligent passive sensor function block diagram
Intelligent passive sensors are based on RFID protocols, and the transmission frequency ranges from 860 to 960 MHz. First, the RFID reader sends a read command, and is charged for the RFID sensor. When the RFID chip is charged, the associated sensor information is read, and the antenna is fed back to the RFID reader.
Advantages of intelligent passive sensors
Compared with existing sensors, intelligent passive sensors have many advantages: existing sensors need to place detection sensors, power, control, and communication chips, single-chip microcontrollers, etc., so that the size is large, the cost is maintenance; while intelligence Each node of the passive sensor is to passively discover the intelligent label power, single-chip microcomputer and data processing on a separate reader, no battery, small size, like tape, each reader supports multiple labels, and thus cost Low, no maintenance needs.
Although the UHF RFID auxiliary electronic tag is also a passive label, the node does not require a battery, the only ID of the TID code and the electronic tag code (EPC), but the surface reflection of the working adsorption material will reduce effective reading distance, and no sensor function; intelligence The passive sensor has no working adsorption material surface reflection, thereby upgrading the effectively read distance, integrated humidity, pressure, distance, and temperature detection such as sensor function.
Intelligent passive sensor application example
A smart passive sensor reader can read thousands of sensing information, so only one reader is required to meet multiple antennas, such as liquid level detection, tire pressure monitoring (TPMS) , Temperature detection, seat detection, rain scraping, indoor air and front large lamp moisture / leak detection, etc.
Figure 2: A reader meets unlimited vehicle sensor application requirements
Seat detection
Seat detection is a system that guarantees the safety of occupants through sensors. Commonly used seat detection systems are judged based on weight or pressure, any object such as a bag of food grocery, will also trigger a safety belt warning, and the error rate is relatively high.
In the new smart passive sensor scheme of Anni Mei Semiconductor, the wireless sensor tag is embedded in the seat (the humidity sensor tag embedded chair back, the pressure sensor tag embedding cushion). The humidity label can determine if someone on the seat can determine if someone on the seat is, eliminate the troubles of the article trigger the safety belt warning, improve the reliability; the pressure label determines the size of the passenger by weight, and will give the occupant to the intelligent airbag control unit Enhance safety in an optimized airbag release angle. This scheme detects the number of remaining seats in the car, which can be extended to the detection of the rear seat and child safety seat, and multiple seats share a control unit (reader) to control, embedded passive humidity sensors do not need any Wire harness and connector.
2. Liquid level detection
Automotive level detection includes detection of fuel tank oil, oil level, brake liquid level, and acidic liquid level. The current automotive level detection system on the market needs to connect wires to the inside of the sink.
The intelligent passive sensor of the Ansian Semiconductor can make no lead and electrical problems in the sink: liquid level detection with the dielectric constant of the fluid, and can detect a variety of liquids including water, gas, gasoline, oil, solvent acid, etc. The bonded humidity sensor is placed outside of the sink, the sensor tag does not exceed 4 inches, and the long distance measurement can use multiple tags, and accurate measurements can be achieved by detecting the communication pipe. The two sensors are mounted on the upper and lower ends, passing Changes of dielectric constants are detected (e.g., gas mixtures).
3. Rainlight sensor - automatic wiper start control
The wiper control system used in the current car is based on sunlight refraction, which is susceptible to interference. The innovative intelligent passive sensor uses humidity detection, covering a wider area of the windshield, and a plurality of humidity sensor labels can be attached to different locations on the windshield, detect the high dielectric constant on the windshield, block The number of wind-glass sensors can be detected by calibration determination, and the light sensor can be detected. The next generation of products can be installed inside the antenna to the glass, using the sensor engine between the two pieces to detect the change in electrical impedance, and implement the smart wiper control of only one sensor.
4. Regional wireless temperature monitoring
When the wireless region for temperature monitoring, a conventional temperature sensor leads are all active, and the installation location is limited. Innovative intelligent passive sensors can be used in multiple area wireless temperature monitoring, unique RFID identification code support automatic identification, reader is connected to the interior gateway, automatic air conditioning system can read data in real time to automatic high-precision control, built-in- 40 ° C to +85 ° C (+/- 1 ° C precision) Measuring range, the next generation of products will support temperature of 125 ° C or higher.
5. Tire pressure monitoring system
The tire pressure monitoring system is used as a real-time automatic monitoring of tire pressure in the driving process, and timely alarms in time when there is insufficient tire pressure or too high, it is timely alarm, enhances driving safety and fuel economy, and extend tire use time, and reduce the wear of suspension systems. . The multi-chip sensor currently used in the tire pressure monitoring system is installed in each rim and valve stem. The battery is powered, the power consumption is higher than 250 UW, and the speed is required to avoid the battery when the tire is not moved. Reproduction is required during the rotation of the tire to position, the cost is higher than $ 30.
The intelligent passive sensor of the Ansian Semiconductor is a single-chip program, no battery and acceleration sensor, a single sensor module power consumption below 15 UW, and the tire pressure and temperature information can be detected regardless of the tire rotation or still. Smart Passive Sensor Tags are placed in each tire, and the only RFID identifier supports automatic tire positioning, software does not need to be reprogrammed.
6. Automobile offline leakage detection
The vehicle factory will perform high pressure water test before the car is exported: turn off the car doors and windows, from different angles to high-pressure water spray from different angles to test the sealing performance of the car and the water seepage. The current market has more manual detection, time consuming, and easy error. Once the leakage is detected, the car must be removed to the chassis for repair.
ANANM Semiconductor's intelligent passive sensor is used for such applications, typical configurations contain six to more than six sensors, allocate unique EPCs, according to the specific needs of the vehicle and the specific needs of the vehicle factory, placed in specific detection Location or water flow convergence points for leakage detection, factory workers only need to hold readers to query sensor labels, no need to detect.
Compliance, safety and EMI performance
Ansian Semiconductor Tests in different occasions / configuration readers, antennas and 9 sensor tags based on CISPR-25 Class 3, through external regional transmission test, and maximum transmit power in RF transmission frequency ranges from 860 to 960 MHz. 33 DBM (about 2 W), follow FCC Part 15 and FCC 47CFR2: 0Et (<1 W), EMC complies with CISPR-25 Class 3 specification, and the RFID area band does not cross interfering with other frequency bands.
Since the intelligent passive sensor itself does not have internal energy, it is transmitted through RF, so there is no security concerns. In terms of the reader, due to its work in the UHF RFID band 860-960MHz, it is in line with the International Protocol ISO / IEC 18000-6C standard. This band is in the low end of the electromagnetic spectrum, which is lower than the radiation of the car, and the system maximum output power 2 W (33 dBm) is as large as a mobile phone, so there is no safety and health risk.
Products and kits that can be ordered
Currently, Semiconductor smart passive sensor may be provided as a sample model, based on AMS RFID IC + 8-bit microcontroller + Reference Design Reader CAN transceiver 3 to 6 dBi UHF receiving antenna reference design, and effective reading system Distance simulation model, antenna placement location optimization suggestion, open source sample code, and basic / advanced function development kit.
Conclusion
As the world's second largest non-microcontroller vendor, inheriting 50 years of automobile semiconductor experience, Anshen Semiconductor continues to promote high energy innovation in the automotive field, the company's recent smart passive sensor is the world's first passive No additional microcontroller controlled intelligent sensors, single-chip, no controller sensing function to improve car intelligence, passive wireless characteristics to reduce car bundle. The internal integration of the chip has a dedicated data processing kernel and temperature, humidity, pressure, distance and other sensors. It does not require battery, ultra-thin, ultra-small volume, low cost, which makes it useful for difficulty in contact, and needs more. Sensor function, such as seat detection, liquid level detection, rain scraping, tire pressure monitoring, vehicle leak detection, etc., its flexible mounting position and customizable size and functional design helps the development of smart vehicles.
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