Digital thermometer with PIC16F84 circuit

Quick Solutions to Questions related to Digital thermometer with PIC16F84:

• How does this thermometer measure temperature without a separate sensor?
  It measures temperature by counting variations in the PIC16F84A watchdog timer time-out period, which varies with temperature.
• Can the thermometer work while minimizing power consumption?
  Yes. The PIC16F84A stays in SLEEP mode by default, consuming little current, and wakes only when a key is pressed.
• What are the operating modes of the WDT thermometer?
  The three modes are SLEEP Mode, Display Mode (shows temperature in degrees Centigrade), and Calibration Mode (creates new calibration values).
• How is temperature translated into an actual reading?
  The system establishes a time-out to temperature calibration, counts WDT time-outs over a period, and equates the count to a temperature.
• Why use a microcontroller-based thermometer instead of an analog thermometer?
  Because it allows building a complex, low-cost solution with few external components that provides high-precision measurement.
• Does the WDT time-out period remain constant?
  No. The WDT time-out period varies with temperature, VDD, and part-to-part process variations.
• When does the PIC16F84A update the WDT count?
  It updates the WDT count when it wakes from SLEEP mode after a key press and checks for additional key presses before returning to SLEEP.