Wireless Embedded Systems and Networking Lab Day 2: Part 1: Add your own external sensorsMagnetic Reed SensorConnecting sensors to expansion portConfiguring Switch Port.Interrupt vs. SamplingUsing RTDConcept of resistive sensors.Attach RTD to ADC portConfigure ADC port, resistor, referenceMeasurement using a sensor nodeConversionA Sample Sensor BoardSample Sensor Board7/10/2007AIIT Summer Course - D#1Wireless Embedded Systems and Networking Lab Day 2:Part 1: Add your own external sensorsLab Assistant: Jaein JeongUniversity of California, Berkeley7/10/2007AIIT Summer Course - D#2Magnetic Reed Sensor•Study the resistance of the magnetic reed sensor open and closed. •Discuss pull up, expected voltage and current.7/10/2007AIIT Summer Course - D#3Connecting sensors to expansion port7/10/2007AIIT Summer Course - D#4Configuring Switch Port.•Enable Device.•Name the states.7/10/2007AIIT Summer Course - D#5Interrupt vs. Sampling•Discuss interrupt versus sampling. •Exercise 2-1: set the alarm on humidity.7/10/2007AIIT Summer Course - D#6Using RTD•Exercise 2-2: Study the resistance of the RTD in ice water versus room temperature versus tea. Ice WaterRoom TemperatureTeaResistance of RTDTemperature7/10/2007AIIT Summer Course - D#7Concept of resistive sensors.•Discuss voltage divider, reference voltage. Mapping readings to engineering units. •Exercise 2-3: What valueRcomp should be set to?•For a Primer Pack node, VADC0is between 0 to 4095 (12-bits).Internal to Sensor NodeRthRcomp VCCADC0VPU00 00 0 (if )0 (if 0)compADC VPUcomp thADC VPURV VCC V VCCR RV V= =+= =7/10/2007AIIT Summer Course - D#8ADC0GNDVPU0Attach RTD to ADC port•Connect one end to ADCx, the other to GND.•Try with your own node. Internal to sensor nodeWiring to sensor node7/10/2007AIIT Summer Course - D#9Configure ADC port, resistor, reference1. Enable Port to Use.2. Configure Each Port.7/10/2007AIIT Summer Course - D#10Measurement using a sensor node•Conduct same measurements using a sensor node.–Measure temperature using the RTD connected to a node.–Try both in ice water versus in room temperature.•Compare results to expectations.7/10/2007AIIT Summer Course - D#11Conversion•Pull data into excel using the data export facility and do the conversions.Raw Reading TemperaturePoint 1Point 2Point 3Point 4Point 57/10/2007AIIT Summer Course - D#12A Sample Sensor Board•Resistive sensor: photo resistor•Voltage sensor: voltage divider with variable resistor•Actuator: LED7/10/2007AIIT Summer Course - D#13Sample Sensor Board1KIO0Rcomp: Programmable Potentiometer in Primer Pack Sensor NodeRphotoRcomp (set close to 100K)VCCADC0VPU0Rv (0 – 100K)Rpu (100K)Rcomp (set close to 0
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