MCU enables precise ultrasonic sensing

Maxim Integrated Products increases its MCU product line with the MAXQ7667 SoC mixed-signal MCU that targets ultrasonic sensor applications. The SoC features a highly integrated data-acquisition system for applications that must measure weak signals over long distances or identify multiple targets. Its integrated functions allow designers to add intelligence to cost-sensitive sensor-conditioning applications. It is suited for automotive-sensor systems including electronic parking assist and park-distance control. It can also be sued for industrial processing, automation, and handheld applications requiring position measurement.

This 7mm x 7mm device integrates the main functional blocks required to accurately measure position, including burst control (pulse transmission), analogue echo reception, DSP, and an MCU. This advanced integration reduces system cost and increases sensor-mounting options.

It features a programmable burst-frequency generator to compensate for transducer tolerances, adjust frequency with temperature, and perform diagnostics. Programmable burst and duty cycles can optimise power to match environmental conditions. The echo receive path includes a variable gain amplifier, a 16bit sigma-delta ADC, a digital band pass filter to eliminate out-of-band noise, and a digital demodulator with low pass filtering to create an echo envelope. Echo detection is supported by an interrupt-generating, 16bit threshold detector with programmable threshold and hysteresis levels. The MCU can be used for additional signal processing, or it can act as the threshold detector.

The integrated 16bit, 16 MIPS MCU supports 32KB of flash, 4KB of data RAM, and 8KB of utility ROM. The MCU can be programmed to dynamically optimise parameters, vary threshold based on time and noise, optimise frequency to match the transducer, and adjust power and threshold based on the location of targets. Additional features include a general-purpose ADC for diagnostics and temperature measurement, a LIN-compatible UART with address capability, three general-purpose timers with interrupt capability, a system timer, GPIO pins with interrupt capability, and single-supply operation.

The MAXQ7667 is available in a space-saving 48-pin LQFP package, and is fully supported over the -40°C to +125°C automotive temperature range. Prices start at Rs.388.92 ($8) for 1,000-up, FOB USA. An evaluation kit is available to speed designs. This kit includes an evaluation board and a PC-based IDE (integrated development environment), which provides a debugger, assembler/linker, time-limited version of the IAR C-compiler and simulator.

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