basic stamp to generate pwm to control temperature

0001T

Hello...i chanced upon this forum searching for information on pulse width modulation

I am doing a school project whereby I need to control the temperature of a heating element such that it will not overheat. I was told to use pwm to control the output current to 0.8A [noparse][[/noparse]electical resistive heating]·for a period of time.

I have access to a basic stamp 2 but the fact is·I do not know how to use it. Is there anyone or any data sheet/ manuals that I can refer to?

Thank you.

Mr. Richard

The best place to start would be a book published by Parallax. The book is a great way to get started in microprocessor control. It can be downloaded for free here

http://www.parallax.com/detail.asp?product_id=27207

look at the bottom of the page for the link "What's a Microcontroller v2.2 (.pdf)"

after that keep asking questions here

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Magic Smoke Theory of Electronics –
Inside every electronic part there is magic smoke.
The magic smoke is what makes everything work.
If you release the magic smoke, the part stops working!

Martin Hebel

You may want to also check out the "Process Control" text from Parallax since nearly 1/2 the text deals with temperature control.
http://www.parallax.com/detail.asp?product_id=122-28176

-Martin (Author)

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StampPlot - GUI and Plotting, and XBee Wireless Adapters
Southern Illinois University Carbondale, Electronic Systems Technologies

0001T

finally, i have got hold of the bs2 & now learning to do the programming.

instead of using the pwm function, i chose to use pulsout...this is the simple program which i've got...

counter VAR Word

DO
DEBUG ? IN3

IF IN3 = 1 THEN

FOR counter = 1 TO 5
PULSOUT 0, 50000
PAUSE 1000
NEXT

PULSOUT 1, 10000

FOR counter = 1 TO 5
PULSOUT 0, 50000
PAUSE 2000
NEXT

PULSOUT 1, 10000

ENDIF
LOOP

however, i realised that each time i press the pushbutton [noparse][[/noparse]normally open type] connected to IN3, the program must complete one cycle. how do i go about modifying the program such that the moment i release the pushbutton, the program would stop?

thanks

Bruce Bates

0001T -

Presently the DO ... LOOP combination is causing your program to run indefinitely. If you want just one iteration, then remove both commands. If you want it to continue for some finite period, you may want to use LOOP with the UNTIL option:

LOOP UNTIL counter = 10 or somethng like that.

Regards,

Bruce Bates

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Unsoundcode

Hi, EXIT will allow you to exit a loop, just look for the release of the button.If the condition is true exit the loop and wait for the next button press.

main:
Timer=1000··· 'initialize pause time
DO WHILE IN3<1··· 'wait for button press
LOOP

DO WHILE Counter<10····· 'loop 10 times
Counter=Counter+1
IF Counter=6 THEN Timer=2000···· 'on count 6 make pause 2000
PAUSE Timer
IF IN3=0 THEN EXIT·· 'exit on button release
PULSOUT 0, 50000
LOOP

Counter=0···· 'initialize Counter

GOTO main······ 'go do it again

If the pulsout assigned to pin·1 is for indication that the heater is on then add these two lines either side of the pulsout 0 line.

HIGH 1
PULSOUT 0, 50000
LOW 1

Jeff T.