how to connect my A.C. with my laptop

[j4jaydeep]

hello...

i have one question

how to program non-computer device with my laptop..

For Example:

if i want to program my Air Condition timing and if i want to make any change in circuit board of my A.C. than which programming language should i use...???

one of my friend told me that i have a knowledge of COBOL language.. is it true???

please help me friends...

[puntoMX]

You don't have to know any programming language, just logic. Just buy a timer for your AC or buy a programmable logic board that is controlled by your laptop. You'll better start to learn electronics or look for a ready-to-go solution.

[R.E]

I think he wants to tinker with the controller chip on his AC... it will be in a propriety language or code and probably stored in a ROM chip anyway. If your lucky and its in C or a variant you could use COBOL... but why, do you need it to interface with a stapler? Most likely you'd need to know Assembly and if your lucky and they used a PIC Chip, you could "technically" replace it with a programmable one...

[CoffeeFiend]

probably stored in a ROM chip anyway

Not likely. Virtually all small-ish microcontrollers use onboard flash these days (others mainly use external NAND flash). The days of external ROMs are long over (last I've seen it was in 8051-based hardware from 10+ years ago where the code was too big to fit in flash at the time). Using a ROM chip would add unnecessary cost and complexity. It's not supported by most modern MCUs either (I'm really glad those days are over)

If your lucky and its in C or a variant you could use COBOL...

It could be C, but something so simple and produced with such a high volume could be written in assembly as well (it saves a bit of flash, which saves a tiny amount of money on the MCU, which adds up nicely at this volume of sales). Using cobol here would make no sense. I've never seen or heard of a MCU programmed in cobol and it's not exactly popular for new projects on the PC side either (it seems to be mainly used on mainframes today).

Most likely you'd need to know Assembly

...if you want to reverse-engineer the original firmware, yes. But that would take forever (even if you're used to read disassembled code e.g. figuring out where/how it drives the multiplexed 7 segment displays or interprets the IR pulses from the remote). And it won't be x86 assembly either (it might even be something no disassembler supports, including IDA Pro), and large parts of it will be specific to particular MCU they used (e.g. how GPIO pin directions are set, registers for clock prescaling, watch dog timers and so on). You'd also need to figure out what goes to which pin. Nevermind that it's almost certain that the flash is protected/secured anyway so it's most likely not an option in the first place.

if your lucky and they used a PIC Chip

That's highly unlikely. I'd expect to find chips from many other MCU lines well before that.

Either ways, it would be quicker to build a new controller from scratch and it's most likely your only option too. You'll have to figure out:

-how to drive the compressor, condenser fan and evaporator's blower (using a relay, triac, etc)

-the fan (blower) speeds might be done via PWM or multiple windings on the motor

-how to read the existing temp sensors or otherwise substitute your own, and the pressure sensors too if there are any

-ideally interface with the existing buttons and also reuse the 7 segment displays (otherwise redo it all from scratch) if you want to preserve its look

-reuse the IR sensor for the remote or add your own (you'll have to record/analyze the codes sent by the remote yourself as well, in order to write code to interpret it later)

-add anything else you might want as an extra (like for communicating with your PC)

-create a new schematic for your new circuit then route the PCB (or use a proto board), repeat as necessary to fix design mistakes (create new prototypes)

-using a pre-made board (like puntoMX already said) is a bit quicker, but it's not very well adapted to the task (e.g. the one linked to buy puntoMX can't read the necessary sensors -- there are plenty of others though. Lots of hobbyists would chose an arduino board for this kind of stuff)

-write the code to drive the multiplexed 7 segment displays (or control a hd44780 LCD controller if you prefer), write the code to decode the infrared pulses from the remote control and so on

-ideally you want the temperature to be controlled with a PID controller (have fun tuning it by changing the constants)

-you have to recreate all the cycle types (standard, energy saver, etc) you want by yourself

-you may need to calibrate your temperature sensors for better accuracy (a lot of popular sensors can have an offset of a couple degrees Celsius in either direction)

-if you want to control it with your PC then you have to write that software as well i.e. design some communication protocol to make both exchange data, then write the code to make it work for both the MCU and your PC

It's several weeks or a few months of full-time work for someone who *really* knows what he's doing. And knowing what you're doing is not optional here. You need to be pretty good at writing code in C for the microcontroller (this better not be your first project in C!). Same thing for the program you want to run on your PC if you want it to do anything interesting (communication, intelligent control, graphing, data logging, etc). It all has to be very stable too. You're also playing with mains voltage so beware (risks of electrocution, fire, etc). Also, when working in such equipment (rewiring stuff) you have to be careful not to damage refrigerant lines. This is definitely not a project for beginners.

I could help (I've worked on a couple HVAC controller designs) but it looks like you lack a lot of expertise to make this happen on your own.

[R.E]

Umm why you went through the lengths you did to take snippets of my response out of context and to pick apart one of my first my posts here is beyond me. You don't think I was serious about COBAL at all do you... did you miss the stapler part? PIC chips are everywhere still... especially in the cheaper $80.00 AC units and lots of cheap companies still use OTP ROM or Eprom which still can be found in modern MCU's today, (I'm looking at examples right now). Rooftop units and quality units use better parts and have more complexity and will most certainly use a dedicated MCU, EEproms or flash, etc.. I too have experience in commercial HVAC, have run a repair shop for over 14 years, and a degree in Industrial Electronics and Robotics, so I like to think I know what I'm doing. The way you dissected and promptly decided to debunk everything I posted has made me feel quite unwelcome especially coming from an Moderator.

Quote.

[CoffeeFiend]

you did to take snippets of my response out of context

It's just a commenting style. It's easier to follow this way (IMO) than a long winded reply without clearly seeing what one is replying to. In other words, it's meant to put things in context.

You don't think I was serious about COBAL at all do you...

Sometimes it's hard to sense sarcasm and such things by reading plain old text (no smilies or anything either). I thought you were totally serious. I've seen plenty of people who would say things like that and even weirder things (it's the internet, weird people aren't exactly uncommon), even on this forum. If I read it again it now makes sense, especially if you insert a period after "variant".

PIC chips are everywhere still... especially in the cheaper $80.00 AC units

Not to say they are not used or that you don't know what you're saying but I have yet to come across one. Since were talking about cheap window units specifically I'll provide one example: LG/Goldstar uses Samsung's SAM87RC series MCUs (for example the C8475).

and lots of cheap companies still use OTP ROM or Eprom which still can be found in modern MCU's today, (I'm looking at examples right now)

OTP? Absolutely. But EPROM on a modern MCU i.e. a windowed part? We must have different definitions of modern then. Unless you meant EEPROM which is quite something else and not a separate ROM chip like you were talking about in your first post.

The way you dissected and promptly decided to debunk everything I posted has made me feel quite unwelcome especially coming from an Moderator

That wasn't the intent and I'm sincerely sorry if it made you feel that way. Also, the moderator status doesn't really make one all that special, it mostly means we waste time deleting spam or warez posts on a daily basis.