Converting-Deep-Freezer-into-Refrigerator---Pic18f4520

Created a switch using Servo motor to turn on / off the deep freezer. Servo controlled by PWM pulses.

The on off switch is controlled with the help of servo motor. Pin configuration: RA0 : LM35 temperature sensor connection RC0 : LED ON for temperature between 1-4 deg Celcius. RC2 : PWM output on PIC. Servo controlled with PWM. RD0-RD7 : Data pins of LCD. RE0 : Rs pin of LCD RE1 : rw pin of LCD RE2 : en pin of LCD

calculations for registers:

Internal oscillator selected with frequency 8MHz. declared in OSCCON register. For using PWM, CCP1CON register is used. CCP1CON uses Timer2.

1. Fosc = 8 MHz (internal Oscillator) Therefore, OSCCON = 0x72
2. Fpwm = 10KHz
3. PR2 = 199

Alternatively, time delays can also be used to control the servo motor. 0-180deg servo motor selected which moves back and forth from 0deg to 180deg 0deg -> 3% duty cycle -> 1.5 milli sec 90deg -> 12% duty cycle -> 2 milli sec

for 3% duty cycle :

CCPRxL : CCPxCON <5:4> = (200 * 3)/100 = 6(dec) = 0b0000000110 hence, CCPRxL = 1 -> 8bits MSB CCPxCON = 0x2C

for 12% duty cycle :

CCPRxL : CCPxCON <5:4> = (200 * 12)/100 = 24(dec) = 0b0000011000 hence, CCPRxL = 0b00000110 -> 24(dec) -> 8bits MSB CCPxCON = 0x0C -> 2 bits LSB and PWM values.