POT command

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.

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

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

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.