thermocouple to pc connection by serial port?

There are many questions.

Do you want serial data (RxD), and how many bits (8-24) ? Do you want a single chip solution ? Is bit banging the non-asnyc bit lines OK ? ( Using DTR and CTS instead of RxD for data )

Google found lots of hits that may be of interest.

Since you want to build your own, are you able to program single chip processors ?

Which ones ?

Here is a one-wire example -

Enjoy

Donald

Wow, I had no idea this would be so complex.

Well these two links are of help, thanks!

None. Willing to learn though. Thought trying to learn interfacing my Type K thermocouple to the serial port would be easier than interfacing to any other pc port.

Any suggested introductory literature (online or offline) to someone learning how to use his first ADC?

Thanks

Mike

Mike,

There are so many directions to go.

ADCs are just one small part of a complete system.

As a beginner, I would suggest a micro-processor kit. Many microprocessors have ADCs built in.

You do realize that your journey is just starting.

If you just want to use your thermocouple, just buy what you need and get it done.

Then learn micros "off-line" so the thermocouple project won't wait.

There are many starter kits for micros available.

First off, are you a programmer at all ?

If yes, then you understand compilers and linkers and maybe even loaders. If no, well you have a long journey ahead of you.

Try going here:

and see if there is anything you can buy to help you get started.

Once you get started, you will find hundreds of boards out there to buy. There are also lots of compilers and interpreters for whichever chip you chose.

Good Luck.

Donald

got it already... but would be nice to have a data logger as well as an instantaneous readout.

took a C, C++ and intel x86 class (I understand x86 is far different from the assembly language of Atmel etc.)

Oh, gee, thanks. I thought the USB would be hardest... here I thought I could rip apart an old mouse for some hardware...

I'll ponder this some more. low-voltage-DC to AC... hmm... would it be easier to have the circuit vary the frequency or the amplitude as the DC voltage changes?

Try reading this and see one way to get hardware working:

Heres another one:

This one even I would buy.

Wow, this guy takes his barbecue seriously. A PWM fan controller to adjust airflow/temperature... ingenious!

Thanks for the tips, all.

Mike

The serial port is probably the most difficult PC port to use with homebuilt hardware. The parallell port is easier IMHO. If you can use the sound card, all you have do do is to convert your signal do AC. A 16-bit soundcard is fairly accurate in its frequency range. /SvenW

Build a voltage to frequency converter, then send the output of the V-F into your sound card input. You can see the results without any programming with a freeware counter software from

Just keep the frequency output within the range of your sound card, which is usually 20 Hz - 20 KHz. You'll need some signal conditioning and amplification before going into the V-F, but it's not hard to get started.

--
Dave M
MasonDG44 at comcast dot net  (Just substitute the appropriate characters in 
the address)

Never take a laxative and a sleeping pill at the same time!!

Yes, maybe. It has got the serial interface hardware already made. But I don't know how to connect to it ... roll the ball ?..

---

To vary the frequency would be the most accurate, because errors in the sound-card could easily be avoided. To vary the amplitude would probably be easier. You could chop the small sensor signal directly using a HC4066 switch or a mos (or dmos) transistor and amplify the AC, thus an accurate DC amplifier is not really needed. Calibration is needed, I would think. Use some intermediate chopper frequency in the range 200Hz-1kHz. Use a multiple of the net frequency, 50 or 60 Hz.

/Regards, Sven W

Most? Compared to USB the serial port is a walk in the park.

True, but not *that* much easier than the serial. ...and if only a bit or two is needed there isn't a difference.

A good suggestion.

--
  Keith

Assembler is assembler, it's got differet op-codes but the principles are the same.

Bye. Jasen

How about pulse-width modulation, insted of conversion to AC? Would it work to take the DC from the thermocouple, run this through a PWM circuit, then connect the output of this to the sound card?

Yes, probably. But read the specs on DC offset and stability for the PWM circuit carefully, as a thermocouple normally has a rather low DC output voltage. /SvenW

Say, where could I find the specs on the max. peak voltage that the Microphone Input on a soundcard can take, without distorting and of course without damaging it?

I tried google for microphone specs, but found instead all sorts of audio-related data instead of peak-to-peak max voltage. Is the max typically 1V? 5V?

I don't have an oscilloscope, otherwise I'd just measure the outputs from my CD player headphone jack...

Thanks,

Mike

sure, for that u have to use microcontroller 89C51 with ADC, which will convert analog signal to digital.

On 22/12/2005 the venerable snipped-for-privacy@yahoo.com etched in runes:

Why not use a MAX6675 thermocouple interface with cold-junction compensation? It has an SPI compatible interface which can very easily be connected to an AVR mega8 with a serial port.

--
John B

impedance 600 ohm approx.; few tenth mV (under 100mV max.)

-- Seasons Greetings & Regards , SPAJKY ® mail addr. @ my site @

more than 3y - "Tualatin OC-ed / BX-Slot1 / inaudible setup!"