Patent ID: 6320512
Filing Date: 2001-11-20
Classification: G01K

Abstract:
A temperature monitor, comprising:a microcontroller;a thermistor with a first end connected to a thermistor pin on said microcontroller;a reference resistor with a first end connected to a reference pin on said microcontroller, and a second end connected to a second end of said thermistor; anda capacitor connected to a junction between said thermistor and said reference resistor;wherein said junction between said thermistor, said reference resistor, and said capacitor is connected to a sample pin on said microcontroller;wherein said microcontroller is arranged to:charge said capacitor only through said reference resistor until a predetermined voltage at said sample pin is reached;measure a reference charging time taken to reach said voltage;discharge said capacitor;charge said capacitor only through said thermistor until said voltage at said sample pin is reached;measure a thermistor charging time taken to reach said voltage;compute a thermistor value by dividing said thermistor charging time by said reference charging time to eliminate errors caused by capacitor variances; andconverting said thermistor value into a corresponding temperature.