原标题：Freescale MCF51MM256人体活动监视器参考设计

　　freescale公司的MCF51MM256是低成本低功耗高性能ColdFire V1系列32位MCU,工作频率高达50.33 MHz,主要用于手持计量设备.本文介绍了MCF51MM256主要特性,框图,以及人体活动监视器参考设计RDACTIVITYMONITOR主要特性,框图和应用示意图,电路图,材料清单和PCB外形图.

　　The MCF51MM256 series devices are members of the low-cost, low-power, high-performance ColdFire V1 family of 32-bit microcontrollers (MCUs) designed for handheld metering devices.

　　MCF51MM256主要特性:

　　32-Bit ColdFire V1 Central Processor Unit (CPU)

　　• Up to 50.33 MHz ColdFire CPU above 2.4 V and 40 MHz CPU above 2.1V and 20 MHz CPU above 1.8 V across temperature range of -40℃ to 105℃.

　　• ColdFire Instruction Set Revision C (ISA_C).

　　• 32-bit multiply and accumulate (MAC) supports signed or unsigned integer or signed fractional inputs.

　　On-Chip Memory

　　• 256 K Flash comprised of two independent 128 K flash arrays; read/program/erase over full operating voltage and temperature; allows interrupt processing while programming.

　　• 32 KB System Random-access memory (RAM).

　　• Security circuitry to prevent unauthorized access to RAM and

　　Flash contents.

　　Power-Saving Modes

　　• Two ultra-low power stop modes. Peripheral clock enable register can disable clocks to unused modules to reduce currents.

　　• Time of Day (TOD) — Ultra low-power 1/4 sec counter with up to 64 sec timeout.

　　• Ultra-low power external oscillator that can be used in stop modes to provide accurate clock source to the TOD. 6 μs typical wake up time from stop3 mode.

　　Clock Source Options

　　• Oscillator (XOSC1) — Loop-control Pierce oscillator; 32.768 kHz crystal or ceramic resonator dedicated for TOD operation.

　　• Oscillator (XOSC2) for high frequency crystal input for MCG reference to be used for system clock and USB operations.

　　• Multipurpose Clock Generator (MCG) — pll and FLL; precision trimming of internal reference allows 0.2% resolution and typical +0.5% to -1% deviation over temperature and voltage; supports CPU frequencies from 4 kHz to 50 MHz.

　　System Protection

　　• Watchdog computer operating properly (COP) reset with option to run from dedicated 1 kHz internal clock source or bus clock.

　　• Low-voltage detection with reset or interrupt; selectable trip points; separate low voltage warning with optional interrupt; selectable trip points.

　　• Illegal opcode and illegal address detection with reset.

　　• Flash block protection for each array to prevent accidental write /erasure.

　　• Hardware CRC to support fast cyclic redundancy checks.

　　Development Support

　　• Integrated ColdFire DEBUG_Rev_B+ interface with single wire BDM connection supports same electrical interface used by the S08 family debug modules.

　　• Real-time debug with 6 hardware breakpoints (4 PC, 1 address and 1 data).

　　• On-chip trace buffer provides programmable start/stop recording conditions.

　　Peripherals

　　• USB — Dual-role USB On-The-Go (OTG) device, supports USB in either device, host or OTG configuration. On-chip transceiver and 3.3V regulator help save system cost, fully compliant with USB Specification 2.0. Allows control, bulk, interrupt and isochronous transfers.

　　• SCIx — Two serial communications interfaces with optional 13-bit break; option to connect Rx input to PRACMP output on SCI1 and SCI2; High current drive on Tx on SCI1 and SCI2; wake-up from stop3 on Rx edge.

　　• SPI1 — Serial peripheral interface with 32-bit FIFO buffer; 16-bit or 8-bit data transfers; full-duplex or single-wire bidirectional; double-buffered transmit and receive; master or slave mode; MSB-first or LSB-first shifting.

　　• SPI2 — Serial peripheral interface with full-duplex or single-wire bidirectional; Double-buffered transmit and receive; Master or Slave mode; MSB-first or LSB-first shifting.

　　• IIC — Up to 100 kbps with maximum bus loading; Multi-master operation; Programmable slave address; Interrupt driven byte-by-byte data transfer; supports broadcast mode and 11-bit addressing.

　　• CMT — Carrier Modulator timer for remote control communications. Carrier generator, modulator and driver for dedicated infrared out (IRO). Can be used as an output compare timer.

　　• TPMx — Two 4-channel Timer/PWM Module; Selectable input capture, output compare, or buffered edge- or center-aligned PWM on each channel; external clock input/pulse accumulator.

　　• Mini-FlexBus — Multi-function external bus interface with user programmable chip selects and the option to multiplex address and data lines.

　　• PRACMP — Analog comparator with selectable interrupt; compare option to programmable internal reference voltage; operation in stop3.

　　Measurement Engine

　　• ADC16 — 16-bit successive approximation ADC with up to 4 dedicated differential channels and 8 single-ended channels; range compare function; 1.7 mV/×C temperature sensor; internal bandgap reference channel; operation in stop3; fully functional from 3.6 V to 1.8 V, Configurable hardware trigger for 8 Channel select and result registers.

　　• PDB — Programmable delay block with 16-bit counter and modulus and prescale to set reference clock to bus divided by 1 to bus divided by 2048; 8 trigger outputs for ADC module provides periodic coordination of ADC sampling sequence with sequence completion interrupt; Back-to-Back mode and Timed mode.

　　• DAC — 12-bit resolution DAC; configurable settling time.

　　• OPAMPx — 2 flexible operational amplifiers configurable for general operations; Low offset and temperature drift.

　　• TRIAMPx — 2 trans-impedance amplifiers dedicated for converting current inputs into voltages.

　　Input/Output

　　• Up to 68 GPIOs and 1 output-only pin.

　　• Voltage Reference output (VREFO).

　　• Dedicated infrared output pin (IRO)with high current sink capability.

　　• Up to 16 KBI pins with selectable polarity.

　　• Up to 16 pins of rapid general purpose I/O (RGPIO).

　　图1. MCF51MM256框图

　　人体活动监视器参考设计RDACTIVITYMONITOR

　　An activity monitor is a small device that records information about user’s physical activity patterns. The device should normally run continuously for long periods of time. Activity monitors can frequently interpret and summarize the recorded data. This instrument is a noninvasive acquisition system and the basic module that it must include is a pedometer, which measures vertical acceleration to count steps and accumulate total time spent at certain activity intensity. When positioned correctly, this device could record each step and can also measure common activities like going up and down the stairs, bending to tie your shoes, etc. They are normally worn on the user’s hips or on the wrist.

　　Besides including a pedometer module an activity monitor can integrate several functionalities. This will help going further on with the body measurements, making the results even more accurate. This is the case of Freescale’s Activity Monitor reference design, which besides the pedometer features a Heart-Rate detection module that helps monitoring physical activity intensity.

　　As normally expected, age is a key factor while measuring physical activity, and not only age but the user’s height, weight, and gender are also very important elements when trying to be accurate. So, it is very convenient to include a personal data acquisition system in the activity monitors. This way all of the user’s biometrics are variables incorporated in the physical activity algorithms.

　　As an example, the Journal of Sports Sciences provided the following calorie expenditure formulas for each gender:

　　Men:

　　Calories Burned = [(Age x 0.2017) - (Weight x 0.09036) + (Heart Rate x 0.6309) - 55.0969] x

　　Time/4.184

　　Women:

　　Calories Burned = [(Age x 0.074) - (Weight x 0.05741) + (Heart Rate x 0.4472) - 20.4022] x Time/4.184

　　All of these information collected help people get a real measurement of their physical activity. Whether they want to get fitter or even if they want to see improvement in their preferred sport the more you can know about your body, the better.

　　The Activity Monitor board is a highly integrated design compounded by several modules which include a TFT display, touch sensing interface, accelerometer, and USB connectivity, among other characteristics.

　　The major features of the Activity Monitor include:

　　• Freescale’s MCF51MM256 Flexis™ 32-bit ColdFire® V1 Microcontroller

　　• Freescale’s MMA7660 Three-axis Low-g Digital Output Accelerometer

　　• Freescale’s MC13202 2.4 GHz Low Power Transceiver for ZigBee® Applications

　　• Freescale’s MC34673 Li-Ion or Li-Polymer Battery Charger (Through USB)

　　• Fingertip acquired Heart Rate detection module

　　• USB Connectivity (Freescale’s CMX USB Stack)

　　• Touch Sensing Interface (Freescale’s Xtrinsic Touch Sensing Software)

　　• 1.8" TFT Display - 128 x 160 pixels

　　• Micro SD card slot

　　• Magnetic Buzzer

　　图2. 人体活动监视器参考设计框图

　　图3. 人体活动监视器参考设计外形图

　　图4. 人体活动监视器参考设计编程连接图

　　The activity monitor is meant to improve health performance, so users can have a better management of their fitness and health activities. It is meant to promote the use of low-power medical applications or any other application requiring precision analog instrumentation to develop highly-integrated portable devices that can assist users in taking care of their health.

　　The device measures user’s burned calories in their daily activity, keeps record of the food and calories ingested during the day, and can monitor their heart rate which is a very useful tool while exercising. This device exhibits the features and potential of Freescale’s MCF51MM Flexis™ 32-bit ColdFire® V1 Microcontroller.

　　图. 人体活动监视器参考设计应用示意图

　　图. 人体活动监视器参考设计PCB外形图:顶视图

　　图. 人体活动监视器参考设计PCB外形图:底视图

　　人体活动监视器参考设计材料清单: