Posted on Jul 16, 2012 10128
22pF capacitors keeps the clock accurate. Read the XTAL specifications to determine what capacitor value is the indicated for it. Time and date are displayed as HH:MM:SSx mmm dd, where: HH = Hours MM = Minutes SS = Seconds x = AM/PM mmm = Month (Jan, Feb, Mar) dd = Day. I/O pins A2, A3, A4 and A5 of the 16F628 are not used. I reserved these pins to connect a LM75 (LM75 uses I2C communication) and display the temperature. Actually, I'm not developing any application using communication, so, any modification will be done until next year. (The name will change to LCD clock with Thermometer and Calendar). Another way to build a thermometer without using any protocol is using a thermistor. Unfortunately, thermistors are not accurate and need calibration. However, The microcontroller doesn't need an A/D converter to connect it.