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Light Sensor . Mike Michaud, Ben Carocari , Mackenzie Higgins. Problem Statement. Build a circuit that includes an analog sensor that is compatible with a computer. Major Components of Circuit. Sensor A/D Converter Sensor to computer connection Microprocessor Software. LDR.
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Light Sensor Mike Michaud, Ben Carocari, Mackenzie Higgins
Problem Statement Build a circuit that includes an analog sensor that is compatible with a computer.
Major Components of Circuit • Sensor • A/D Converter • Sensor to computer connection • Microprocessor • Software
Light Detecting Resistor: How it works • Change in resistance in the circuit depending on how much light is present • Photons from light hit the semi-conductive LDR and “excite” the electrons which break their atomic bonds and begin flowing (current). • more light = less resistance • less light = more resistance • The increase in current results in a drop in resistance
Microcontroller • Mbed NXP LPC1768 • 40 pin configuration • Voltage range 4.5v - 9.0v • Max current 500mA
Microcontroller Features • Onboard A/D Converter • Micro USB cable connection to the computer • Free software • Real-time clock battery backup input VB
Syncing with the computer • Drag and drop programming • Reset circuit • Plug in and run • Download code into program • Added visual reference
Program Interface • Hyper-Terminal • Works with C/C+ code • Needed a program to decode the digital information • Graphical design • Updated rapidly for real time information
Why the Mbed? • USB connected • Compatibility with software • Labview • Hyper-terminal • Drag and drop programming • Reset features • Easy pin configuration
How to complete your sensor this week. • Analog sensor • thermistor, LDR, pressure gauge, strain gauge, etc • Analog to digital converter • DAQ, onboard A/D • Connect to computer • USB, serial port • Get software compatible with microcontroller/ DAQ • Experiment