This document discusses the implementation of IEEE 802.15.4-based communications in wireless sensor nodes for biomedical signal monitoring. It describes using the MiWi protocol to implement a simplified version of IEEE 802.15.4 in a personal area network coordinator and body temperature sensor node. It also discusses testing the network performance with a packet sniffer and transmitting packet headers and data between nodes.

1. Implementing IEEE 802.15.4-based
Communications in Sensor Nodes aimed for
Biomedical Signal Monitoring
Gustavo Meneses Benavides
Colombia

2. Abstract
We present the most significant issues found during
the implementation of IEEE 802.15.4-based
communications in a set of wireless sensor
nodes developed for biomedical signal
monitoring. The technical specifications of the
Personal Area Network Coordinator and these
of a body temperature sensor node are
described. ..
…in order to provide a monitoring instrument to
conduct experiments which could provide
useful information for individuals and
researchers.

3. Communications
for
Wireless
Sensor Networks for Biomedical
Signal Monitoring

4. MiWi™:
Microchip’s IEEE 802.15.4-Based
Protocol
MiWi™ protocol is a lightweight choice which allows
us incorporating midrange microcontrollers in this
application and take advantage of a simplified
version of IEEE 802.15.4, better suited to our smallsized, low cost network implementation.
…IEEE 802.15.4 compliant RF transceivers and a set
of microcontroller references compatible with the
MiWi protocol available at reasonable costs from a
variety of suppliers in our country .

5. IEEE 802.15.4
 IEEE 802.15.4 (2003)
 IEEE 802.15.4 A (2006)

6. EnViBo Wireless Sensor Network

7. Sensor Nodes

8. PAN Coordinator

9. Implementing IEEE 802.15.4
Communications

10. MPLAB Project coding

11. MAC PDU Structure

12. Packet Header Format

13. Packet Header Example and
Color Code of the sniffer

14. Testing Network Performance
with Packet Sniffer

15. Simplified Handshacking

16. Packet Transfer Between Nodes

17. …SOME RESULTS
 Firmware: C18 & C30 based (8bit-16 bit
MCUs)
(for Sensor Nodes and PAN Coordinator)
 Circuit Designs
(Schematics and PCB)
 System’s Gateway Design
 User Interfaces
(Labview , ------>Android OS)
 Tests
 EnViBo Platform Proposal

18. Platform User Interface

19. CONCLUSIONS
 Significant adjustments over the base code files provided by





Microchip to build a wireless monitoring network that can operate
under the IEEE 802.15.4-based Microchip’s MiWi protocol.
Network roles tested with prototypes for the PAN coordinator and
sensor nodes capturing vital signs like body temperature.
A comprehensive work to add functions and coding to implement
the features specific to network elements according to their role and
function level within the monitoring system proposed.
Tests conducted on different prototype boards have allowed to
improve the designs and put into operation a reduced-size/lowpower optimized version of sensor node, which meets our
requirements
User interfaces are available in some test nodes through LCD
modules, and in a computer as a virtual instrument interface.
Data logging options are available (microcontroller’s data
EEPROM, SD card, in the computer by using data in time & date

20. REFERENCES
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and
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