POT command

[Helios]

hi there

i am a mechatronics engineering student and about to make a dc motor servo control, and i don't want to be involved into (Analog to digital) stuff.

i want to use the POT to take the feedback signal from the tachogenerator (small dc motor with 6 volt rated) and change the control signal according too it, so as the speed changes the PIC start the compensation for the error.

waiting for your help

thanks in advance.

[Dave]

Helios, The POT command executes a charge and discharge of a capacitor connected to a resistor (pot) connected to 1 pin of the processor. The time is then measured and a value is made available. For the input you have available you will need an A/D channel to evaluate the speed. Sorry.....

Dave Purola,
N8NTA

[Acetronics2]

Hi, Helios ( The sun ... wow !!! )

Try to use RCTime instead of POT, to measure a voltage ... there are applications on the Web.

BUT you'll have to use a Lookup table ... as response to voltage give an exponential law.
also ... no measure below 1.5v !!!

See µChip DS 40040B

See Nuts and Volts Vol1 p 133 ( Parallax site ) : The real way of POT working !!!

see also : http://www.emesystems.com/BS2rct.htm

MY Thought ... if you see how simple it is to use an ADC ( PIC or outside ) ... the soft programming work with POT orRCTime looks like using a hammer and chisel to program the Chip !!!

Alain

[Helios]

thanks guys for help, i really appreciate this

and i 'll use the A/D instead of POT after i saw the site which acetronics sent ... it is a hilti issue :d

thanks again.