Developed by Elmos Semiconductor, the devices simplify the design of infotainment and driver-assistance systems.
By Murray Slovick, Contributing Editor
Automotive sensors monitor and manage electrical, chemical, and physical changes in the car. On this front, Elmos Semiconductor, which develops semiconductors and sensors primarily for use in vehicles, recently unveiled infrared-based solutions for optical proximity/gesture recognition and ultrasonic ICs for parking assistance. Let’s examine these new devices one at a time.
Gesture-Recognition IC Combo
The new Elmos E909.21 (controller) and E909.22 (conditioner) ICs comprise a plug-and-play solution tailored to gesture-recognition applications (Fig. 1). Designed for larger automotive displays and used together, the parts can detect the following actions: approach, swipe, air slider, and magnification. Object-recognition and motion-evaluation functions are conducted in real time using simple infrared technology.
In operation, the system detects the optical reflections of an object in front of the sensor by using a principle called HALIOS (High Ambient Light Independent Optical System), which is effective in the suppression of ambient light. A self-calibration capability also is employed to eliminate disturbances caused by housing reflections and scratches. HALIOS can address capacitive proximity sensing by using the integrated charge amplifier (capacitive sensors can detect and measure anything that’s conductive or has a dielectric different from air, such as a human hand).
The E909.21/ E909.22 module has two receivers and four LED transmission channels as well as a special HALIOS compensation path. For each transmit channel, 100-mA current drivers are integrated on the IC.
The HALIOS switching frequency can be set to 1 MHz to eliminate interference with other optical systems. And its integrated 16-bit Harvard Architecture CPU can be variably clocked at 4, 8, 12 or 24 MHz. In addition, 32-kB flash, 4-kB SRAM, and 8-kB SysROM are integrated into the IC. Operating temperature range is from −40 to +85°C. The E909.21 comes in the QFN32L5 package; the E909.22 in a QFN20L4 package.
On request, the device comes with an integrated bootloader, too, which allows the device to be programmed via one of its two serial interfaces (I²C/SPI). In addition, the developer is supported by firmware demo code when creating the initialization and calibration routines. Numerous application notes and a gesture library complete the development environment.
“Direct-Drive” Parking Assistance
Following its E909.21/ E909.22 introduction, Elmos Semiconductor launched E524.32 and E524.33, the company’s next-generation “Direct-Drive” IC family for ultrasonic parking-assistance systems.
The direct-drive approach is so-called because the integrated driver stage drives the connected ultrasound transducer directly, significantly reducing system cost and size by removing the transformer and other external components on the sensor board. Other advantages include reduction of required assembly pick and place handling, a smaller printed-circuit-board (PCB) and sensor housing area and reduction of PCB layers (a two-layer PCB is possible, instead of the typical four layers).
Digital signal processing (automatic thresholds, sensitivity, time control, etc.) optimizes short- and long-range detection performance. A smart damping algorithm reduces the blind zone and the new near-field detection function identifies objects directly in front of the sensor.
To ensure flexibility for customer applications, the I/O interface offers three configurable measurement profiles that can be set up for near, medium and far range. An additional, second configurable threshold and advanced dynamic gain curve settings provide further options. Reliable sensor operation is assured via diagnosis that includes monitoring the supply voltages and temperature, as well as detection of communication errors and/or the measurement of decay time and frequency deviation.
Communication with the control unit is possible with a choice of a two- or three-wire version. The two-wire version (E524.32) offers bidirectional communication with data modulation on the supply line (Fig. 2). The three-wire versions (E524.33/34/35) have a dedicated I/O line for data transmission.
Elmos Semiconductor points out that compared to its predecessor ICs, the measurement performance, as well as the electrostatic-discharge (ESD) and electromagnetic-compatibility (EMC) behavior of the devices, have been significantly improved. In the far-range mode (and depending on the type of transducer) the ICs can detect a 75-mm standard round obstacle up to a distance of about 4 meters. For larger obstacles, more distant targets can be successfully detected. At close range, a new, redesigned Smart Damping algorithm reduces transducer settling time so that minimum distances of <12 cm can be measured with a single transducer. The new near-field detection function detects objects already in front of the sensor and issues a warning by means of a flag.
Communication over the different interfaces is almost identical to the Elmos E524.08/09 ICs, so that both new ICs can be mixed as desired in the vehicle depending on customer requirements. If higher ranges are required, the E524.08 and E524.09 ICs can be used. If the requirements are lower and system costs are paramount, the E524.32 and E524.33 may be more suitable.