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[原创] Microchip PIC24FJ128GC010低功率血压计解决方案

关键词:医疗电子 血压计 MCU PIC24FJ128GC010

时间:2015-10-30 10:22:49       作者:Microchip       来源:中电网

microchip公司的PIC24FJ128GC010是完整模拟信号链的模拟片上系统,集成了片上高精度16位ADC及10 Msps的12位ADC以及一个DAC,两个运算放大器(运放),并具备能够延长便携式医疗和工业应用电池寿命的超低功耗技术(XLP).主要用在便携式医疗监控设备如血糖仪和血压计,以及便携式监控设备如电压和电流监控器,气体传感器和高转速传感器阵列等工业应用.本文介绍了PIC24FJ128GC010多种特性,框图,以及血压计(BPM)主要亮点,框图和电路图.

The PIC24FJ128GC010 family expands the capabilitiesof the PIC24F family by adding a complete selection ofadvanced analog peripherals to its existing digitalfeatures. This combination, along with its ultralow-power features, Direct Memory Access (DMA) for peripherals, USB On-The-Go (OTG) and a built-in LCDcontroller and driver, makes this family the newstandard for mixed-signal PIC® microcontrollers in oneeconomical and power-saving package.

PIC24FJ128GC010模拟特性:

• 12-Bit, up to 50-Channel,High-Speed,PipelineAnalog-to-Digital Converter (A/D):
- Conversion rates up to 10 Msps
- Compatibility features for low conversion rates
- Flexible operating modes with auto-accumulate,Threshold Detect and channel scan usingsample lists
- Conversion available during Sleep and Idle
• 16-Bit Sigma-Delta Analog-to-Digital Converter (A/D):
- Programmable data rate with dithering option andadjustable oversampling ratios
- Two differential channels
- Configurable input gain stage
• Two 10-Bit Digital-to-Analog Converters (DAC):
- Fast settling time supports 1 Msps update rate
• Two Rail-to-Rail, Input/Output, General PurposeOperational Amplifiers:
- 2.5 MHz gain bandwidth product (typical)
- Flexible input multiplexing options
- Optional Comparator mode
• Three Rail-to-Rail, Enhanced Analog Comparatorswith Programmable Input/Output Configuration
• Three On-Chip Programmable Voltage References
• Charge Time Measurement Unit (CTMU):
- Used for capacitive touch sensing, up to50 channels
- Time measurement down to 100 ps resolution
- Operation in Sleep mode

PIC24FJ128GC010极低功耗特性:

• Multiple Power Management Options for ExtremePower Reduction:
- VBAT allows for lowest power consumption onbackup battery (with or without RTCC)
- Deep Sleep allows near total power-down, withthe ability to wake-up on internal or externaltriggers
- Full RAM and state retention in select Deep Sleepand VBAT modes
- Sleep and Idle modes selectively shut downperipherals and/or core for substantial powerreduction and fast wake-up
- Doze mode allows CPU to run at a lower clockspeed than peripherals
• Alternate Clock modes allow On-the-Fly Switching toa Lower Clock Speed for Selective Power Reduction
• Extreme Low-Power Current Consumption forDeep Sleep:
- WDT: 270 nA @ 3.3V, typical
- RTCC: 350 nA @ 32 kHz, 3.3V, typical
- Deep Sleep current, 75 nA, 3.3V, typical

PIC24FJ128GC010通用`1串行总线特性:

• USB v2.0 On-The-Go (OTG) Compliant
• USB Device mode Operation from FRC Oscillator –No Crystal Oscillator Required
• Dual Role Capable – Can Act as Either Host orPeripheral
• Low-Speed (1.5 Mb/s) and Full-Speed (12 Mb/s)USB Operation in Host mode
• Full-Speed USB Operation in Device mode
• Low Jitter PLL for USB
• Supports up to 32 Endpoints (16 bidirectional):
- USB module can use any RAM location on thedevice as USB endpoint buffers
• On-Chip USB Transceiver with Interface for Off-ChipUSB Transceiver
• Supports Control, Interrupt, Isochronous andBulk Transfers
• On-Chip Pull-up and Pull-Down Resistors

PIC24FJ128GC010外设特性:

• LCD Display Controller:
- Up to 59 segments by 8 commons
- Internal charge pump and low-power, internalresistor biasing
- Operation in Sleep mode
• Up to Five External Interrupt Sources
• Peripheral Pin Select (PPS); Allows Independent I/OMapping of Many Peripherals
• Five 16-Bit Timers/Counters with Prescaler:
- Can be paired as 32-bit timers/counters
• Six-Channel DMA Supports All Peripheral modules:
- Minimizes CPU overhead, increases datathroughput and lowers power consumption
• Nine Input Capture modules, each with a Dedicated16-Bit Timer
• Nine Output Compare/PWM modules, each with aDedicated 16-Bit Timer
• Enhanced Parallel Master/Slave Port (EPMP/EPSP)
• Hardware Real-Time Clock and Calendar (RTCC):
- Run, Sleep, Deep Sleep and VBAT modes
• Two 3-Wire/4-Wire SPI modules (support 4 Framemodes) with 8-Level FIFO Buffer
• Two I2C™ modules Support Multi-Master/Slavemode and 7-Bit/10-Bit Addressing
• Four UART modules:
- Support RS-485, RS-232 and LIN/J2602
- On-chip hardware encoder/decoder for IrDA®
- Auto-wake-up on Auto-Baud Detect (ABD)
- 4-level deep FIFO buffer
• Programmable, 32-Bit Cyclic Redundancy Check(CRC) Generator
• Digital Signal Modulator (DSM) Provides On-ChipFSK and PSK Modulation for a Digital Signal Stream
• High-Current Sink/Source (18 mA/18 mA) on All I/O Pins
• Configurable Open-Drain Outputs on Digital I/O Pins
• 5.5V Tolerant Inputs on Select Pins

PIC24FJ128GC010高性能CPU特性:

• Modified Harvard Architecture
• Up to 16 MIPS Operation @ 32 MHz
• C Compiler Optimized Instruction SetArchitecture (ISA)
• 8 MHz Internal Oscillator:
- 96 MHz PLL option for USB clocking
- Multiple clock divide options
- Run-time self-calibration capability for maintainingbetter than ±0.20% accuracy
- Fast start-up
• 17-Bit x 17-Bit Single-Cycle HardwareFractional/Integer Multiplier
• 32-Bit by 16-Bit Hardware Divider
• 16 x 16-Bit Working Register Array
• Two Address Generation Units (AGUs) for SeparateRead and Write Addressing of Data Memory

PIC24FJ128GC010微控制器特性:

• Supply Voltage Range of 2.0V to 3.6V
• Two On-Chip Voltage Regulators (1.8V and 1.2V) forRegular and eXtreme Low-Power Operation
• 20,000 Erase/Write Cycle Endurance Flash ProgramMemory, Typical
• Flash Data Retention: 20 Years Minimum
• Self-Programmable under Software Control
• Programmable Reference Clock Output
• In-Circuit Serial Programming™ (ICSP™) andIn-Circuit Emulation (ICE) via 2 Pins
• JTAG Boundary Scan Support
• Fail-Safe Clock Monitor Operation:
- Detects clock failure and switches to on-chip,low-power RC Oscillator
• Power-on Reset (POR), Power-up Timer (PWRT)and Oscillator Start-up Timer (OST)
• Separate Brown-out Reset (BOR) and Deep SleepBrown-out Reset (DSBOR) Circuits
• Programmable High/Low-Voltage Detect (HLVD)
• Flexible Watchdog Timer (WDT) with its OwnRC Oscillator for Reliable Operation
• Standard and Ultra Low-Power Watchdog Timers forReliable Operation in Standard and Deep SleepModes

图1.PIC24FJ128GC010框图

血压计(BPM)

A Blood Pressure Meter (BPM) is a non-invasive device used to measure blood pressure. A blood pressure meter, or sphygmomanometer, is a device that is used to measure blood pressure. The meter is used with an inflatable cuff for restricting blood flow and a pump to inflate the cuff. Digital blood pressure meters typically measure both systolic and diastolic pressures by an oscillometric detection method, using a piezoelectric pressure sensor.

A digital blood pressure meter allows easy monitoring of blood pressure at home, in a doctor’s office or in a hospital. Today’s blood pressure meters must meet the demands of measuring, storing and transmitting blood pressure, pulse and other medical data. To meet these demands, Microchip offers a broad portfolio of highly integrated microcontrollers, semiconductors, software and development solutions. These include integrated products with low-noise analog signal conditioning, touch technology, LCD control, wired/wireless connectivity, motor control, multiple low-power modes and high-speed memory.

A blood pressure meter, or sphygmomanometer, is a device that is used to measure blood pressure. The meter is used with an inflatable cuff for restricting blood flow and a pump to inflate the cuff. Digital blood pressure meters typically measure both systolic and diastolic pressures by an oscillometric detection method, using a piezoelectric pressure sensor.

图2.血压计(BPM)板外形图

The Microchip Blood Pressure Meter Demonstration was implemented using the system-on-a-chip PIC24FJ128GC010 MCU.
The features of this MCU are:
eXtreme Low Power (XLP) technology
18 nA Deep Sleep mode
240 nA Watch Dog Timer operation in Deep Sleep modes
180 µA/MHz Run mode
16-bit Delta-Sigma Analog-to-Digital Converter (ADC): 2 differential channels
12-bit 10 Msps pipeline ADC: 50 channels
Two 10-bit 1 Msps Digital-to-Analog Converter (DAC)
Two operational amplifiers
Three comparators
Three voltage references
Charge Time Measurement Unit (CTMU)
USB with Device/Host/OTG support with active clock tuning (no crystal required)
Segmented LCD driver with charge pum
This reference design helps to develop a low-cost, low-power, handheld or portable blood pressure meter with user interface.*
System Diagram

图3.血压计(BPM)板框图

血压计(BPM)主要亮点:

Measures both systolic and diastolic pressures
Measures heart rate
Low overall BOM cost due to high level of integration
eXtreme Low Power (XLP) operation
Measure While Inflating (MWI) algorithm used to reduce patient discomfort
Utilizes the PIC24FJ128GC010’s integrated Pulse-Width Modulation (PWM) module to drive the air pump’s motor in fast or slow speed mode
Integrated LCD controller generates the data and timing control required to directly drive a static or multiplexed LCD panel
High-pass filter implemented with one of the PIC24FJ128GC010 MCU’s integrated operational amplifiers
MCP1802 LDO converts the 5V or 6V main input voltage to 3.3V VDD

图4.血压计(BPM)框图

图5.血压计(BPM)板电路图(1)

图6.血压计(BPM)板电路图(2)

图7.血压计(BPM)板电路图(3)

图8.血压计(BPM)板电路图(4)
详情请见:
http://ww1.microchip.com/downloads/en/DeviceDoc/30009312c.pdf
http://ww1.microchip.com/downloads/en/DeviceDoc/Blood_Pressure_Meter_Schematic_RevB.pdf
以及http://ww1.microchip.com/downloads/en/AppNotes/00001556B.pdf
30009312c.pdf
00001560A.pdf
Blood_Pressure_Meter_Schematic_RevB.pdf

 

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