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Touch=E9! (choking back up my snack)

I once had a classic "avocado" fridge that used almost as much electricity as Al Gore, papered with bumper stickers to improve it. I should've tried foam.

-- Cheers, James Arthur

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You're in Australia or NZ?

Altronics or MicroZed in Australia

In NZ:

$4.80 NZ

$7.11 NZ

As for cable - it is one 9 pin "D" plug with TXD RXD and GND used. - the other end is anything you want and one or two resistors to the PICAXE chip

North Island

How slow is the mail in NZ?

part

$7 more than what? The *highest* price I could find for the chip was about $11 NZ - double that for postage and your still well ahead of a PICKIT 3. (If you can claim to program a micro-controller in assembly then don't you already have a programmer that "burns" a chip?)

There are suppliers of PICAXE on both the north and south islands of NZ and if none of them are any good then they do post - which is what an RS solution would be. The "programmer" for a PICAXE is *literally* one resistor which limits current from the RS-232 port to to chip (the chip will still program at logic levels if you have one of those USB-RS232 converter things).

"Programming" goes like this - You apply 2 to 5.5 volts to the PICAXE chip. The inbuilt, combined bootstrap/interpreter automatically runs and continuously monitors the "serial in" (program) pin. When a valid signal appears the PICAXE writes the program to flash (and eeprom if you used that too) and then starts running the program)

There are lots of good reasons not to use a PICAXE.

-Maybe you can't write a fridge temperature control program in just one thousand line of code.

-Maybe it will take you more attempts than the 10000 times you can reprogram the thing to get a "bang-bang" controller working.

-Maybe you need more than 28 general purpose byte variables, 256 bytes of scratch pad RAM and 256 bytes of EEPROM to store the state of the fridge control algorithm algorithm

-Maybe your algorithm needs more computation power than 8000 multiplies or divisions per second and the chip isn't up to the job

-Maybe you need more than the 6 I/O pins (you could just use a bigger PICAXE chip)

-Maybe you need more than 3 x 10 bit ADC's

-Maybe you don't like how the I2C software support allows you to read temperature directly in one command but only from a Dallas DS18D20

-Maybe you just don't like the English or you pathologically hate any language called "BASIC" even though it PICAXE BASIC borrows heavily from bot Java and C++

Whatever it is might be valid, but "price" is a joke.

If anyone can't afford a 9 pin plug and a resistor I will send them one and for Christmas I will even add a meter of 3 way cable and a plastic cover for the plug.

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PICKIT 3 vs. PICKIT 2 is around $7 to $8 more.

That's what the PICKITs are for.

I don't think that would be a problem.

Probably not.

Yes, definitely. We would need that much ram just for the stack. We cannot use the PICAXE.

May be not, but faster chips are always better, if not too expensive.

Yes, definitely. We would need 10 to 15 I/Os. We cannot use the PICAXE.

Yes, probably 4 to 6 ADCs. We cannot use the PICAXE.

Yes, we don't want to pay for DS18D20. 25 cents thermistors are good enough. We cannot use the PICAXE.

Yes, I hate BASIC dialect of English. I only speak C.

Price is never the issue with useless tools.

We cannot use the PICAXE for any single reason above. I think we have more than one.

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This should do it:

while(1) // loop forever { temp_fridge =3D read_temp(0); // Fridge temperature temp_exch_beg =3D read_temp(1); // Temp. at beginning of exchanger temp_exch_end =3D read_temp(2); // Temp. at end of exchanger temp_room =3D read_temp(3); // room temp.

if(temp_fridge < temp_target) { compressor(TRUE); sleep(TIME_COMPRESSOR); compressor(FALSE);

temp_delta =3D read_temp(2) - read_temp(1);

// push latest value on data stack push_comp_temp(temp_delta);

// if heat exchanger temp. delta is decreased, time to defrost differential_temp();

if(defrost(TRUE)) { heater(TRUE); sleep(TIME_HEATER); heater(FALSE); } }

led_display(temp_fridge); sleep(TIME_IDLE); }

links:

Harvest gold is a big step up from avocado. Our first house had an avocado refrigerator and a harvest gold stove. All the houses in the subdivision were decorated by the same blind contractor.

So you don't have a point.

Of course not. The government won't allow that to happen.

Horseshit. Price isn't everything. Only one component of value is price.

Volume has nothing to do with it.

It already has. Government will see that it continues.

No, the government specifically won't allow it.

Complete bullshit.

--- Why would you hate BASIC and what do you mean by "dialect of English"?

Run through a good compiler, the object code of any programming language should be the same.

---

--- More's the pity.

-- JF

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reg &=3D ~BIT5; reg |=3D BIT7 | BIT 4 | BIT 2; reg >>=3D 4;

when it doesn't. Calling a person a prick does not actually strengthen = your case. Nor does suggesting I'm obtuse or an idiot. It just reflects = badly on you and the wonderful land of Oz.

legislate against it.

since

live.

want to discuss them? Many foolish notions are predicated on a supposed= concern for future generations. =20

You brought the subtopic up first Mrs Tarbom.

all means go and do something worthwhile. : )=20

part

Ah. Got you. And (IIRC) you are correct that a PICKIT 2 won't do PIC24.

My response was in regard to SE's aims for a fridge controller. I don't know what your requirement was.

SE said in a post that she can program in assembler. I make the assumption that she is talking about a micro-controller because that is the context of the thread.

Un-needed for SE if she use's a PICAXE

For a bang-bang controller of a domestic refrigerator (SE's case)? PICAXE is in BASIC. What the user can access is for their exclusive use. The system manges it own stack from separate RAM.

Ah - You can't use PICAXE-08M2. Yo might be able to use PICAXE-20M2. You could use PICAXE-28X2, PICAXE-40X2. They are starting to be expensive, but for a one off, if you don't have a set of tools and a programmer already at hand, still worth a look

You could use PICAXE-28X2, PICAXE-40X2.

The PICAXE also implements plain vanilla 10-bit ADC's. If you want to use a thermistor or just about anything else you can interface to a micro-controller you can. If your an absolute Scrooge and don't care about absolute accuracy you could even use the readinternaltemp command; the hardware for that is free!

Doesn't that make love letters to that special someone difficult to read?

Does it require many #PRAGMA's before you can link up?

-----------------------

One thing that amazes me is that BASIC is often blasted because it is easy to produce unstructured code and has that horrible "GOTO" statement. But C is a great language - you just have to put in lots of effort to produce properly structured code and not use the built in "Goto" command.

Mind you, I do have a bad attitude to C. In uni I mastered Fortran, 8080 (and Z80), 6502, Pascal (I faked my way through Pascal, it just wasn't interesting to me and I couldn't run it at home - thank goodness commenting and analysing the algorithms was important), FORTH and even edlin! - very useful stuff, they didn't even tell us we could type in our name as a command and be amazed and entertained by the resulting chaos. In the last few weeks of the last programming class one of the fellow students asked which language they should specialise in to get a job and they were told "C"!!! (followed by loud expletives from the class)

---------------------------------

This is a useful tool, particularly for one off's with simple requirements. For someone already set up and experienced with another processor maybe not so useful. It did seem that SE didn't have that (since she mentioned buying a programmer)

Mrs Tarbomb, thank you. Which topic?

Cargill

and

No, it is much more of a case of semi open (Wintel) and completely closed (Mac) architectures.

Maybe.

Not at all, Medicare has already seen to that, it has been thoroughly commoditized.

Not by the track record.

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I am also trying to rebuild my busted fridge, with a more intelligent defrost controller. I don't know if you are following the other discussions. We are trying to measure the compressor efficiency and temperature difference, in order to minimize heating and cooling cycles. To do so, we need to have several thermistors readings and to keep track of past operating cycles. At a minimum, the user would need to be able to set the fridge target temperature, as well as other operating parameters. I don't think the PICAXE is sufficient for this.