how to generate P.W.M pulse between 0-100 d.c

[yossi56]

Hello all,I use in mini robot controller (innovation first)
and i try to generate P.W.M pulse between 0 to 100 dutey cycle.
I read R. Kevin Watson pwm (3) files ,but they didnt help me because they are good to - servo pwm pulse.

i need the pwm 0-100 dutey cycle because i connect my p.w.m output from mini robot controller ("innovation first") to L298 (some h bridge componet), and servo (pwm) pulse not matching fot this operation.

What i can need to do to generate P.W.M pulse between 0 to 100 dutey cycle?

thanks yossi

[Kevin Sevcik]

yossi,

The IFI controllers are all based around interfacing with hobby servos and IFI H-Bridges that all take hobby servo pulse-train inputs, so the hardware as configured isn't going to be really useful for what you're attempting. If you're using the full-size IFI Robot Controller, then PWM outputs 13-16 are under direct control of the programmable user processor and are hooked directly into the PIC microprocessors CCP units. You can look in the PIC reference manual and datasheet on Kevin Watson's website to get info on how you could set these up to output a true 0-100% duty cycle PWM output. If you're using the Vex controller, PWM outputs 1-4 are arranged in a similar fashion. If you need more than 4 duty-cycle outputs, then your options are limited:

1. Use the digital IOs combined with timers and really fast interrupt handlers to bootleg a duty-cycle generation output.
2. Find or make a serial to duty-cycle PWM conversion board.
3. Hack the IFI controller's Master hardware and firmware to force it to do what you want it to.

That last option is obviously the most difficult and most likely to totally hose your controller. I'm convinced it's technically possible to pull it off, but it would be very very difficult and it'd require a fairly extensive amount of code decompiling, reverse engineering, etc.

[Jim E]

It sounds like you are taking the 8520 cpu in the mini controller to do something outside of FIRST. This forum deals with FIRST competitions.

That being said, IFI has default software on their website to control all of the pins on the EDU controller. I would guess (I'm not a lawyer) that you could use this software for any purpose, whether for profit or educational purposes. Kevin Watson's code is strictly for educational purposes w/o paying royalties.

You must understand how to program, and understand how to read in C, to use the above solutions. I'm not sure if Easy C supports the PIC18F8520 processor.

You will want to study the 8520 datasheet. It shouldn't be too difficult to figure out how IFI distributes the I/O to the outside world.

IFI has documented this processor. It was used in the 2005 competition in the Full-size RC Controller.

[yossi56]

Thanks jim and Kevin, This Thread will publish to my college studying and I hard to find another forum like this because experience of members here,so sorry if it is not popular to show Threads like this here.

I try to explain my mission and wiil be more solution for me,

In my project I need get 3-16 Volt when my source Vcc is 24 Volt,
i try get the control of this voltage range with PWM pulse (with mini robot controller "innovation first".)

So i serch for new suggestion to do it.

Thanks again,Yossi.