Low-power wireless communication System for Biosignal transmission - MSP430

Low-power wireless communication System for Biosignal transmission

Abstract - Ubiquitous healthcare, which is recognized as a new industrial trend in healthcare arena, means that personal health status is monitored and managed unconsciously during daily life without any institutional interventions. In this respect, unconscious measuring of heart electrical activity is regarded as a core technological part for deployment of ubiquitous healthcare in home and mobile application. Inconveniences which might arise in transmitting measured biological data based on cable protocols generally are recognized critical points in tele-monitoring environment and also restrict the mobility of the user. a. Especially, activity monitoring which is importantly recognized as a core parameter in ubiquitous healthcare arena and weight management, pervasive and wireless measuring technology is most needed. We would like to suggest lower power, miniaturized communication system in order to solve the above problems. The suggested system is powered by small coin-size battery. Even though, the suggested system didn't have higher transmission rate, its low power consumption make the suggested system would be feasible in ubiquitous monitoring of biological signals in ubiquitous healthcare arena.

Project submitted for DesignMSP430 contest by:

Biomedical Instruments& Measurements System Research Lab
Prof. Jeong-Whan Lee,Kang-Hwi Lee, Young-Ha Jo,Woo-chul Jung,Young-Jae Lee
kku99lkh@hotmail.com
http://bimsrl.kku.ac.kr

 

Hardware Design

Main specification of the Biosignal Monitoring Transmit system prototype.

INSTRUMENTATION AMPLIFIER (INA326) -Texas Instruments	110-dB CMRR at G = 100, 100-μV max offset, 0.4-μV/ºC max drift, RRIO, MSOP package
A/D Converter(embedded with MSP430F1232) Ultralow-Power Consumption:	Ultralow-Power Consumption: Active Mode: 200 μA at 1 MHz, 2.2 V 16-Bit RISC Architecture, 125 ns Instruction Cycle Time 10-Bit, 200-ksps A/D Converter With Internal Reference, Sample-and-Hold, Autoscan, and Data Transfer Controller
Wireless Comm.(nRF2401,Nordic, Norway)	True single chip GFSK transceiver in a small 24-pin package (QFN24 5x5mm) ShockBurst™ mode for ultra-low power operation and relaxed MCU performance Low supply current (TX), typical 10.5mA peak @ -5dBm output power Power supply range: 1.9 to 3.6 V
Power	3.3V
Physical Size (W x H )	30*30mm
Current consumption	40mA/h (TX)

 

 Main specification of the Biosignal Monitoring Receive system prototype.

CP2102(USB to UART bridge)	USB to RS-232 converters
A/D Converter(embedded with MSP430F1232)	Ultralow-Power Consumption: Active Mode: 200 μA at 1 MHz, 2.2 V 16-Bit RISC Architecture, 125 ns Instruction Cycle Time 10-Bit, 200-ksps A/D Converter With Internal Reference, Sample-and-Hold, Autoscan, and Data Transfer Controller
Wireless Comm.(nRF2401,Nordic, Norway)	True single chip GFSK transceiver in a small 24-pin package (QFN24 5x5mm) ShockBurst™ mode for ultra-low power operation and relaxed MCU performance Low supply current (TX), typical 10.5mA peak @ -5dBm output power
Power	3.3V
Physical Size (W x H )	60*20mm
Current consumption	20mA/h (RX)

The human medical data acquisition system, in particular the patient monitoring system, presents the challenge to designers of measuring very small electrical signals in the presence of much larger common mode voltages and noise. Front-end amplifiers perform the essential conditioning that complements downstream digital processing, which in turn refines the measurement and communicates with other systems. Biophysical measurements include electrical and mechanical signals for general monitoring, diagnostic and scientific purposes both in clinic and non-clinic environments. Successfully meeting the signal acquisition challenge requires system designers to have knowledge of the signal

source, good design practice and ICs with appropriate characteristics, features and performance. The Texas Instruments MSP430 family of ultralow-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 attribute to maximum code efficiency. The digitally controlled oscillator (DCO) allows wake-up from low-power modes to active mode in less than 6μs.

The MSP430F1232 is ultra low-power mixed signal microcontrollers with a built-in 16-bit timer, 10-bit A/D converter with integrated reference and data transfer controller (DTC) and fourteen or twenty-two I/O pins. In addition, the MSP430F1232 microcontrollers has built-in communication capability using asynchronous (UART) and synchronous (SPI) protocols.

nRF2401 is a single-chip radio transceiver for the world wide 2.4 - 2.5 GHz ISM band. The transceiver consists of a fully integrated frequency synthesizer, a power amplifier, a crystal oscillator and a modulator. Output power and frequency channels are easily programmable by use of the 3-wire serial interface. Current consumption is very low, only 10.5mA at an output power of -5dBm and 18mA in receive mode. Built-in Power Down modes makes power saving easily realizable.

The CP2102 single chip solution includes a complete USB 2.0 full-speed function controller, bridge control logic and a UART interface with transmit/receive buffers and modem handshake signals. The device also features on-board EEPROM, a voltage regulator, a USB transceiver and an integrated internal oscillator, eliminating external components generally required in USB applications.

Firmware Design

- worked on CrossWorks for MSP430
Flow Chart ShockBurst™ Transmit of nRF2401

Software Design
Labview Interface(National Instruments)

References

1. MSP430x2xx Family User’s Guide
2. nRF2401 Single Chip 2.4 GHz Radio Transceiver PRODUCT SPECIFICATION
3. Precision, Rail-to-Rail I/O INSTRUMENTATION AMPLIFIER INA326 Datasheet

Code & Gerber Files

[Code and Gerber Files]