andy firstname.lastname@example.org (Dervish) wrote in message
The problem is that this is a small toy that has motors/gear boxes
already mounted and it isn't worth it to redesign it with
I want to be able to send a PWM signal on 1 of 5 lines to control the
motors. Send motor1 a 1ms pulse, and it turns to 0 degrees. Send it
a 2ms pulse, it turns to 180 degrees. like RC servos
I don't want to tie up the CPU on the robot up with the actually
positioning of the motors. Id like a circuit that has the same
function of a R.C. servo. You give it a pwm signal, and depending on
the width of the pulse, the motor will spin to a certain angle....
I could do this with a PIC and 5 Hbridge chips. I don't have a PIC
The PIC would take either PWM signals as input (or maybe send the
desired rotations as digital data (serially)), then convert the PWM
signal or data into the correct signal to send to the Hbridges.
This would involve attaching a potentiometer to each gearbox. No big
I could control all of the motors with my CPU using the
potentiometer/capacitor combination to give feedback to the CPU. The
CPU could get the current rotation reading from the RC circuit, and
send the appropriate FD/RV signal to the motor, but this ties up CPU
and takes quite a few I/O pins. 5 for the pots, 10 for the Hbridges.
15 I/Os and it eats cpu time. rephrase that. It leaves no time for
the CPU to do anything else.
so I would like to convert the motors to servos. Take 5 I/O lines if
the motors acted as servos, IE 1 PWM output per servo.
Even better would be to send a PIC or other embedded processor the
angle in degrees, and it would move the motor to the correct angle.
If you could send the angles for all 5 of the motors at once, and have
them all moving at different SPEEDs, that would be awesome. I don't
even know how to start looking for a product like this. I can code in
PIC assembly no problem, but I don't own a programmer. I think this
would fix my problem.
1)send PIC the motor#/PWM (or desired angle)
PIC gets feedback from R/C circuit and controls H-bridge to turn the
motor to the correct angle.
It would be great to be able to read the current positions of the R/C
circuit through the PIC also.
seems like someone would have designed something similar.
Anybody know where to look?