Freescale公司的血壓計(BPM)參考設計采用MC9S08QE128作為微控制器,具有控制,數據保持,模擬采集和連接功能以及能和用戶接口. 參考設計具有多種優勢:采用MC9S08JM60作為USB通信的橋,采用MC13202 ZigBee收發器進行2.4GHz通信,采用MRAM來存儲用戶數據和通信,MRAM驅動器能存取MRAM存儲器,采用OLED作為用戶顯示, MPR083接近式傳感器用作用戶接口,以及用兩個定時PWM模塊作為音頻反饋.本文首先介紹了MC9S08QE128主要特性和方框圖.接著介紹了血壓計(BPM)參考設計的硬件方框圖和軟件架構流程圖,以及詳細電路圖和所用材料清單.
MC9S08QE128主要特性:
• 8-Bit HCS08 Central Processor Unit (CPU)
– Up to 50.33-MHz HCS08 CPU above 2.4V, 40-MHz CPU above 2.1V, and 20-MHz CPU above 1.8V, across temperature range
– HC08 instruction set with added BGND instruction
– Support for up to 32 interrupt/reset sources
• On-Chip Memory
– Flash read/program/erase over full operating voltage and temperature
– Random-access memory (RAM)
– Security circuitry to prevent unauthorized access to RAM and flash contents
• Power-Saving Modes
– Two low power stop modes; reduced power wait mode
– Peripheral clock enable register can disable clocks to unused modules, reducing currents; allows clocks to remain enabled to specific peripherals in stop3 mode
– Very low power external oscillator can be used in stop3 mode to provide accurate clock to active peripherals
– Very low power real time counter for use in run, wait, and stop modes with internal and external clock sources
– 6 μs typical wake up time from stop modes
• Clock Source Options
– Oscillator (XOSC) — Loop-control Pierce oscillator; Crystal or ceramic resonator range of 31.25 kHz to 38.4 kHz or 1 MHz to 16 MHz
– Internal Clock Source (ICS) — FLL controlled by internal or external reference; precision trimming of internal reference allows 0.2% resolution and 2% deviation; supports CPU freq. from 2 to 50.33 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
– Illegal opcode detection with reset
– Flash block protection
• Development Support
– Single-wire background debug interface
– Breakpoint capability to allow single breakpoint setting during in-circuit debugging (plus two more breakpoints)
– On-chip in-circuit emulator (ICE) debug module containing two comparators and nine trigger modes. Eight deep FIFO for storing change-of-flow addresses and event-only data. Debug module supports both tag and force breakpoints.
• ADC — 24-channel, 12-bit resolution; 2.5 μs conversion time; automatic compare function; 1.7 mV/°C temperature sensor; internal bandgap reference channel; operation in
stop3; fully functional from 3.6V to 1.8V
• ACMPx — Two analog comparators with selectable interrupt on rising, falling, or either edge of comparator output; compare option to fixed internal bandgap reference voltage; outputs can be optionally routed to TPM module; operation in stop3
• SCIx — Two SCIs with full duplex non-return to zero (NRZ); LINｍａｓｔｅｒextended break generation; LIN slave extended break detection; wake up on active edge
• SPIx— Two serial peripheral interfaces with Full-duplex or single-wire bidirectional; Double-buffered transmit and receive; MSB-first or LSB-first shifting
• IICx — Two IICs with; Up to 100 kbps with maximum bus loading; Multi．ｍａｓｔｅｒoperation; Programmable slave address; Interrupt driven byte-by-byte data transfer; supports broadcast mode and 10 bit addressing
• TPMx — One 6-channel and two 3-channel; Selectable input capture, output compare, or buffered edge- or center-aligned PWMs on each channel
• RTC — 8-bit modulus counter with binary or decimal based prescaler; External clock source for precise time base, time-of-day, calendar or task scheduling functions; Free running on-chip low power oscillator (1 kHz) for cyclic wake-up without external components
• Input/Output
– 70 GPIOs and 1 input-only and 1 output-only pin
– 16 KBI interrupts with selectable polarity
– Hysteresis and configurable pull-up device on all input pins; Configurable slew rate and drive strength on all output pins.
– SET/CLR registers on 16 pins (PTC and PTE)
圖1.MC9S08QE128系列方框圖
采用QE128系列的血壓計參考設計
Blood Pressure Monitor Using the Flexis QE128 Family
The blood pressure monitor (BPM) reference design shows how to implement a system that can measure arterial blood pressure values. The system demonstrates control, data retention, analog acquisition, and connectivity functions, as well as the ability to interface with a user. These are achieved by using several Freescale devices.
This reference design serves only as a proof of concept for this application and is not authorized for use in safety-critical applications such as a U.S. Food and Drug Administration (FDA) class 3 application.
Manufacturers and designers who incorporate Freescale (FSL) technology must have all necessary expertise in the safety and regulatory ramifications involved in the application of this design, and they are solely responsible for all legal, regulatory, and safety-related requirements concerning their products and the use of Freescale devices in safety-critical applications.
采用QE128系列的血壓計參考設計優勢
The BPM reference design elements can be referenced for later development as:
• USB communication using the MC9S08JM60 as a bridge
• 2.4 GHz communication using the MC13202 ZigBee transceiver
• MRAM communications
• Use of MRAM to store user data
• MRAM driver to access MRAM memory
• User display using an OLED display
• User interface using the MPR083 proximity sensor
• Audio feedback using two timer pulse-width modulator (TPM) modules
The main benefit from this solution is that developers are able to take any piece of hardware and/or software and reuse it for their own applications, thus enhancing the design cycle and providing faster development time.
圖2.Flexis BPM 參考設計方框圖
圖3.血壓計軟件架構流程圖
圖4.血壓計參考設計電路圖(1)
圖5.血壓計參考設計電路圖(2)
圖6.血壓計參考設<
