iii. Thermostat that precisely controls your refrigerator internal temperature and extends its operating range below 16°C

Did you know that a PIC18Fxxxxx microcontroller can work on even when PC is turned off? This is precisely how thermostatic support operates. PIC18F26J50 microcontroller must be first programmed with v2.2 firmware that includes thermostatic support functionality. The additional functions are explained in detail in section 5. The thermostat uses two analog inputs to capture temperature from two digital thermometer circuits, one measuring the ambient temperature and the other measuring the temperature inside a refrigerator.

The thermostat support is configured and activated via four USB functions. First, you have to load the following configuration parameters:

1. number of the PIC18F2xJ50 A/D converter input for the ambient temperature measurement (A/D A)

2. number of the PIC18F2xJ50 A/D converter input for the refrigerator internal temperature measurement (A/D B)

3. number of the digital input (0 to 7) that will be used to switch off the refrigerator power supply when the internal temperature drops too low

4. number of the digital input (0 to 7) that will be used to switch on the internal hating inside the refrigerator

5. 10-bit A/D A value at ambient temperature at which PIC18F2xJ50 takes over the control of the refrigerator

6. 10-bit A/D A value at ambient temperature at which PIC18F2xJ50 stops control of the refrigerator

7. 10-bit A/D B value at refrigerator internal temperature when the refrigerator power is switched off (230 V~)

8. 10-bit A/D B value at refrigerator internal temperature when the refrigerator power is switched on (230 V~)

9. 10-bit A/D B value at refrigerator internal temperature when the heating in the refrigerator is turned on (230 V~)

10. 10-bit A/D B value at refrigerator internal temperature when the heating in the refrigerator is turned off (230 V~)

Thermostat software examples (32 and 64-bit) with source code are now available from Downloads section:

Multithreading example with source code (32-bit) based on SVLIB_PIC18F24J50 v2.6.NET4.zip

Multithreading example with source code (64-bit) based on SVLIB_PIC18F24J50 v2.6.NET4x64.zip