possible to output PWM to speed controller from PC parallel port ?

You can do it with some circuitry, for instance, I am using a Velleman K8000 I/O board. I wire the D/A converter output of the I/O board into a comparator. The other input of the comparator is the ourput of a ramp generator. This produces a PWM signal.

Typically, though, you wouldn't want to drive the PWM directly from the parallel port because you will spend a lot of time in I/O and the frequency will be pretty low.

That tells me exactly what I wanted to know. I didn't really think it would be worth the effort since my thoughts on doing this were to simply reduce the number of extra components / controllers for a PC / mini-ITX based robot.

Thanks !

Hi

There seems to be problems with some of the links at the moment, but an excellent site for PC/IO interfacing is at

They have tutorials so you can build your own cards, and write code to control motors using PWM!

Cheers

|-]

Dale

Hi again

If you use Internet Explorer the links are OK...something wrong with Firefox I think...

Cheers

|-]

Cool! I've been using this guy's TRIPOD code and didn't even know he had a working boondog.com site because everytime I looked for it I got a blank page. Thanks !

P.S. This thread is almost gone on my newsgroup server.

I have done it using RT Linux. A real time kernel module generates the PWM and a user space program controls it.

Ed

About 10 years ago I wrote some experimental code to do servo control all in software on a PC without any buffer circuitry needed. It is very crude and may need some tuning to get the pulses the correct spacing, but it moved a servo to different positions using the UP/DOWN keys....

I now use a Mini SSC RS232 controller

-howy

this was compiled using borland C.

/////// start of SEROV1.CPP ////// #include #include #include #include

#define ESCAPE_KEY 0x011b #define UP_KEY 0x4800 #define DOWN_KEY 0x5000 #define LEFT_KEY 0x4b00 #define RITE_KEY 0x4d00

// parallell port address you want to talk to #define PPORT1_DATA 0x03bc

void quit_pgm (void);

void main(void) { int i,j,w=1; long x;

for(;;) { if(w

About 10 years ago I wrote some experimental code to do it all in software on a PC without any buffer circuitry needed. It is very crude and needs tuning to get the pulses the correct spacing, but it moved a servo to different positions using the UP/DOWN keys....

-howy

this was compiled using borland C.

/////// start of SEROV1.CPP ////// #include #include #include #include

#define ESCAPE_KEY 0x011b #define UP_KEY 0x4800 #define DOWN_KEY 0x5000 #define LEFT_KEY 0x4b00 #define RITE_KEY 0x4d00

// parallell port address you want to talk to #define PPORT1_DATA 0x03bc

void quit_pgm (void);

void main(void) { int i,j,w=1; long x;

for(;;) { if(w

This will not work with todays PCs anymore because WIndows messes up your timing in the 'for' loop. Actually, a good compiler will remove the 'fro' loop entirely when optimizing. And last but not least, there is no outportb command on WIn2k/XP anymore. The parallelport can only be talked to via drivers.

I don't run Windoze on my modern PC. Under other operating systems this is not so difficult.

--Works great with a Victor controller and a Stamp. I've done this to run those DC windshield wiper motors. Watch out for capacitor drift..