原标题：Maxim MAX32600可穿戴皮肤电反应(GSR)仪参考设计

　　人的情绪变化总是伴随一系列生理反应如呼吸,血压,脉搏,血管容积和腺体分泌等.和汗腺分泌有关的皮肤电反应常用作情绪变化的一种间接生理指标，是指肌体受刺激时皮肤电传导的变化,一般用电阻值及其对数或电导及其平方根表示.皮肤电(或简称为皮电反应，galvanic skin response,简写为GSR)是反映情绪变化的生理指标。许多心理现象与皮肤电平有密切关系，情绪反应会引起皮肤电平的急剧变化.因此,皮肤电可以作为情绪的生理指标.本文介绍了采用MAX32600的可穿戴皮肤电反应(GSR)仪MAXREFDES73#参考设计,包括MAXREFDES73#系统框图,AC阻抗测量框图,电路图,材料清单和PCB设计图.

　　The MAX32600 microcontroller is based on the industrystandardARM? Cortex?-M3 32-bit RISC CPU operatingat up to 24MHz. It includes 256KB of flash memory, 32KBof SRAM, a 2KB instruction cache, and integrated highperformanceanalog peripherals.

　　The MAX32600 comes in 192-ball, 12mm x 12mmCTBGA and 120-ball, 7mm x 7mm CTBGAand 108-ballWLP packages.

　　MAX32600优势和特性:

　　● Integrated AFE Enables Precision WellnessMeasurements with Minimal Discretes

　　• 16-Bit ADC with Input Mux and PGA

　　Up to 500ksps Conversion Rate

　　PGA with Gain of 1, 2, 4, and 8 and Bypass Mode

　　Differential 8:1 or Single-Ended 16:1 Input Mux

　　Internal Mux Inputs for Measuring VDDA3

　　• Internal or External Voltage ReferenceProgrammable Buffers for ADC and DACs

　　• Two 12-Bit DACs and Two 8-Bit DACs

　　• Four Operational Amplifiers

　　• Four Low-Power Comparators

　　• Four Uncommitted SPST Analog Switches

　　• Four Ground Switches

　　• Up to Eight 100mA LED Driver Pairs (Sink)

　　• Internal Temperature Sensor

　　● Secure Valuable IP and Data with Robust On-BoardTrust Protection Unit

　　• Trust Protection Unit for End-to-End Security

　　• AES Hardware Engine

　　• μMAA for ECDSA and RSA

　　• Hardware PRNG

　　• Fast-Erase SRAM for Secure Key Storage

　　● Industry’s Lowest Overall System Power IncreasesBattery Life

　　• 175μA/MHz Active Power Executing Code from Cache

　　• Less Than 1.0μA Low-Power Mode 0 (LP0) Current

　　• Multiple Power Management Modes to OptimizePower Consumption

　　• Peripheral Clock Control

　　• 6-Channel DMA Engine Enables IntelligentPeripheral Operation While Micro is in Sleep Mode

　　MAX32600主要应用:

　　● Wearable Medical Devices

　　● Pulse Oximetry Measurement

　　● Galvanic Skin Response Measurement

　　● Blood Glucose Metering

　　图1.MAX32600简化功能框架图

　　GSR measurement detects human skin impedance under different situations. A variety of events affect the skin impedance of a human body, such as changes with the ambient environment, stress from a sudden event, and sweating from physical exercises. GSR devices can be used in medical treatment, lie detection, and wellness monitoring. The MAXREFDES73# reference design is a wrist-worn GSR measurement device that monitors both skin impedance and temperature on a user’s wrist. With a mobile device for Android, a user can monitor his or her skin resistance and temperature within 20m through the Bluetooth low-energy (BLE) wireless interface.

　　The MAX32600 microcontroller is the center of the GSR device. The MAX32600 integrates all the analog front-end and other peripherals required for impedance measurements, including one 16-bit ADC with input MUX and PGA, two 12-bit DACs and two 8-bit DACs, 4 operational amplifiers (OP AMP), 4 uncommitted SPST analog switches, and internal voltage references.

　　The MAXREFDES73# reference design is a wearable, mobile galvanic skin response (GSR) system featuring the MAX32600 wellness measurement microcontroller. This battery-powered platform takes high-precision AC impedance measurements while consuming minimal power. The MAX32600 microcontroller features the industry-standard ARM® Cortex®-M3 32-bit RISC CPU that operates at up to 24MHz, while integrating multiple high-performance analog peripherals. Analog features include a 16-bit ADC with PGA, two 12-bit DACs, and a 16-channel multiplexer along with classic digital features such as 256KB of flash memory, 32KB of SRAM, and a 2KB instruction cache. The reference design provides a high-performance and flexible development platform, which is a foundation for many fitness and medical measurement applications, especially galvanic skin response measurement. The reference design arrives as a wrist-worn unit, powered by a LIR2032 rechargeable coin battery. A mobile application program for devices for Android™ provides the interface, and is free for download. The device communicates with a device for Android though a Bluetooth® low-energy wireless interface. Test results, hardware files, and firmware source code provide complete documentation for the design. The complete wrist-worn unit is available for purchase.

　　皮电反应(GSR)仪主要特性:

　　High precision

　　Integrated AFE

　　Low power consumption

　　Compact and low cost

　　和同类产品相比优势:

　　Single-chip AC impedance measurement

　　Wireless communication with mobile device

　　Portable, compact, and cost effective

　　皮电反应(GSR)仪应用:

　　AC impedance measurement

　　GSR measurement

　　图2.MAXREFDES73#系统外形图

　　图3MAXREFDES73#系统框图

　　MAXREFDES73#系统材料清单: