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Acuario · 08-20-13, 12:03 AM

I guess you could call PICs and Arduinos cousins - they are both widely used by hobbyists as they are cheap and the development tools are not expensive. Microchip Technology Inc is where you'll find the info.

The pic I'm using (PIC 16F628A) doesn't have an ADC input so I'm using a Dallas DS18B20 1-wire digital thermometer. The plan being to use the same method as on the defrost circuit I designed previously; i.e. the thermometer is positioned on the back of the machine next to the evaporator and monitors the temperature. When the temperature falls to around zero it triggers a defrost cycle turning of/on compressor and reversing valve as necessary.

There's a bit of fine tuning to be done to the defrost cycle, my biggest problem is the lack of days when the temperature falls sufficiently low to be able to test - I think last winter it was only 2 or 3 mornings at most. I have to test by putting the thermometer in the freezer. It does work fine but I prefer live testing.

When the card is fully debugged I'd be happy to sell you one. As you only have a single unit o control you could use it with an RS232 interface instead of an RS485 although both are readily available on ebay. If I remember correctly, doesn't your unit have a crank case heater as well? I guess you'd need to control this too.

Thanks for the link to the Panasonic control but they are simulating a remote control rather than controlling the machine directly.

Acuario

08-20-13, 12:03 AM	#26
Acuario Apprentice EcoRenovator Join Date: May 2011 Location: Tortosa, Spain Posts: 221 Thanks: 2 Thanked 81 Times in 46 Posts	I guess you could call PICs and Arduinos cousins - they are both widely used by hobbyists as they are cheap and the development tools are not expensive. Microchip Technology Inc is where you'll find the info. The pic I'm using (PIC 16F628A) doesn't have an ADC input so I'm using a Dallas DS18B20 1-wire digital thermometer. The plan being to use the same method as on the defrost circuit I designed previously; i.e. the thermometer is positioned on the back of the machine next to the evaporator and monitors the temperature. When the temperature falls to around zero it triggers a defrost cycle turning of/on compressor and reversing valve as necessary. There's a bit of fine tuning to be done to the defrost cycle, my biggest problem is the lack of days when the temperature falls sufficiently low to be able to test - I think last winter it was only 2 or 3 mornings at most. I have to test by putting the thermometer in the freezer. It does work fine but I prefer live testing. When the card is fully debugged I'd be happy to sell you one. As you only have a single unit o control you could use it with an RS232 interface instead of an RS485 although both are readily available on ebay. If I remember correctly, doesn't your unit have a crank case heater as well? I guess you'd need to control this too. Thanks for the link to the Panasonic control but they are simulating a remote control rather than controlling the machine directly. Acuario Last edited by Acuario; 08-20-13 at 01:05 AM..