Environmental Sensing with TinyOS and Mica2 Motes

1
Environmental Sensing with TinyOS and Mica2 Motes

• April 27, 2006
• EE194WIR Wireless Internetwork
• Wing Siu
• Jason Waterman

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Project Goals

• Measure light and temperature with Motes
• Forward sensor readings using multihop routing to
  Head Node
• Generate alarm if temperature drops below
  programmed threshold
• Turn on LED when light readings drop below
  programmed threshold
• Display readings from Head node on PC

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Measure Light and Temperature

• Light and temperature share the same ADC
• Can only use one sensor at a time
• Two timers, one for each sensor
• Light when there is light, ADC is near full
  scale (1023), near 0 when dark
• Temperature raw sensor readings are
  approximately converted to Fahrenheit at the host

4
Sending Data

• Oscilloscope
• Reads sensor network data from serial port
• Motes send data in packets
• Java program can be used to graph results

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Oscilloscope Packet

• Header
• Destination address (2 bytes)
• Active message handler ID (1 byte)
• Group ID (1 byte)
• Message length (1 byte)
• Payload
• Source mote ID (2 bytes)
• Sample counter (2 bytes)
• ADC channel (2 bytes)
• ADC data readings (10 readings x 2 bytes)

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Surge

• Ad hoc multi-hop routing
• Shortest path first algorithm
• Single destination node
• Transparent operation