PWM Output from an ADC Input
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Can anyone help me out. I am writing my first program. What I am
trying to achieve is to output a PWM signal to control a
proportional solenoid. I want to control it using a potentiometer. I
am passing the potentiometer through an ADC. How do I link the PWM
output to the ADC output so that if the potentiometer moves 50% the
outputted PWM will move the solenoid 50%. I would be most greatful
for any ideas.
hugh
trying to achieve is to output a PWM signal to control a
proportional solenoid. I want to control it using a potentiometer. I
am passing the potentiometer through an ADC. How do I link the PWM
output to the ADC output so that if the potentiometer moves 50% the
outputted PWM will move the solenoid 50%. I would be most greatful
for any ideas.
hugh
Comments
use the Pot command....or RCtime... I guess if you wanted to get fancy you
could hook up an ADC to the stamp...get that running then use that to control
the PWM....
Here's how I'd do it....
Pick an output pin....then get PWM cycle going on that pin. Pbasic has a
command for this....you could do the loops yourself...no need to reinvent the
wheel.
Take that pin's output and run that into a nice N Channel Logic level MOSFET.
The MOSFET has three poles....one to ground...the other to your ground on your
Proportional Solenoid and the last pole goes to the stamp. The MOSFET acts like
a high current switch....it handles the load...the stamp just tells it when to
come on and turn off.
Does this make any sense?? Considering this is your first project I'll give you
some hints. First off you need to read up on the commands. Get the PWM command
running on a sample program. Make sure it's slow and easy to test...maybe hook
up a DC motor to the MOSFET so you can get that all worked out fist. Then you
can read up on the POT or RCTIME commands. Decide how you want to do that part
of the program. Then get a simple program working with RCtime. The parallax
website is full of great documentation and sample programs to get you running.
If you think of big projects in terms of smaller tasks it makes a bit more
sense. You don't build a house in one day.....you have to break it up into
manageable chucks. And it electronics there is a learning curve with each step.
Once you get all the smaller chucks running you can put the entire thing
together and away you go.
And not to knock the stamp....but you could actually do a pot on an 555 chip and
do the same thing. Not as cool or fun...but it can do it too...
Tim
>>> hughgoodbody@y... 12/18/03 10:18AM >>>
Can anyone help me out. I am writing my first program. What I am
trying to achieve is to output a PWM signal to control a
proportional solenoid. I want to control it using a potentiometer. I
am passing the potentiometer through an ADC. How do I link the PWM
output to the ADC output so that if the potentiometer moves 50% the
outputted PWM will move the solenoid 50%. I would be most greatful
for any ideas.
hugh
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