随着人们对汽车辅助驾驶系统智能化要求的提高和汽车电子系统的网络化发展，新型的倒车雷达应能够连续测距并显示障碍物距离，并具有通信功能，能够把数据发送到汽车总线上去。以往的倒车雷达设计使用的元器件较多，功能也较简单。本文介绍的基于新型高性能超低功耗单片机 MSP430F2274 的倒车雷达可以弥补以往产品的不足。

　　【MSP430F2274】

　　16 位超低功耗微控制器，具有 32KB 闪存和 1K RAM

　　描述

　　The Texas Instruments MSP430 family of ultra-low-power microcontrollers consist of several devices featuring different sets of peripherals targeted for various applications. The architecture, combined with five low-power modes is optimized to achieve extended battery life in portable measurement applications. The device features a powerful 16-bit RISC CPU, 16-bit registers, and constant generators that contribute to maximum code efficiency. The digitally controlled oscillator (DCO) allows wake-up from low-power modes to active mode in less than 1 µs.

　　The MSP430F22x4/MSP430F22x2 series is an ultra-low-power mixed signal microcontroller with two built-in 16-bit timers, a universal serial communication interface, 10-bit A/D converter with integrated reference and data transfer controller (DTC), two general-purpose operational amplifiers in the MSP430F22x4 devices, and 32 I/O pins.

　　Typical applications include sensor systems that capture analog signals, convert them to digital values, and then process the data for display or for transmission to a host system. Stand-alone radio-frequency (RF) sensor front ends are another area of application.

　　特性

　　Low Supply Voltage Range: 1.8 V to 3.6 V

　　Ultra-Low Power Consumption

　　Active Mode: 270 µA at 1 MHz, 2.2 V

　　Standby Mode: 0.7 µA

　　Off Mode (RAM Retention): 0.1 µA

　　Ultra-Fast Wake-Up From Standby Mode in Less Than 1 µs

　　16-Bit RISC Architecture, 62.5-ns Instruction Cycle Time

　　Basic Clock Module Configurations

　　Internal Frequencies up to 16 MHz With Four Calibrated Frequencies to ±1%

　　Internal Very-Low-Power Low-Frequency Oscillator

　　32-kHz Crystal

　　High-Frequency (HF) Crystal up to 16 MHz

　　Resonator

　　External Digital Clock Source

　　External Resistor

　　16-Bit Timer_A With Three Capture/Compare Registers

　　16-Bit Timer_B With Three Capture/Compare Registers

　　Universal Serial Communication Interface

　　Enhanced UART Supporting Auto-Baudrate Detection (LIN)

　　IrDA Encoder and Decoder

　　Synchronous SPI

　　I2C™

　　10-Bit 200-ksps Analog-to-Digital (A/D) Converter With Internal Reference, Sample-and-Hold, Autoscan, and Data Transfer Controller

　　Two Configurable Operational Amplifiers (MSP430F22x4 Only)

　　Brownout Detector

　　Serial Onboard Programming, No External Programming Voltage Needed, Programmable Code Protection by Security Fuse

　　Bootstrap Loader

　　On-Chip Emulation Module

　　Family Members Include:

　　MSP430F2232: 8KB + 256B Flash Memory, 512B RAM

　　MSP430F2252: 16KB + 256B Flash Memory, 512B RAM

　　MSP430F2272: 32KB + 256B Flash Memory, 1KB RAM

　　MSP430F2234: 8KB + 256B Flash Memory, 512B RAM

　　MSP430F2254: 16KB + 256B Flash Memory, 512B RAM

　　MSP430F2274: 32KB + 256B Flash Memory, 1KB RAM

　　Available in a 38-Pin Thin Shrink Small-Outline Package (TSSOP) (DA), 40-Pin QFN Package (RHA), and 49-Pin Ball Grid Array Package (YFF)

　　For Complete Module Descriptions, See the (SLAU144)