Re: [CAD_CAM_EDM_DRO] Axis Stall Problems

Wayne C. Gramlich wrote:

> The chopper is implemented using a dedicated Microchip
> PIC16F676 microcontroller (one for each axis) running
> at 20MHz where a couple of A/D lines are used to measure
> the current flowing through each L298 H-Bridge. Each
> axis is being sampled at approximately 20KHz. If the
> current is too high, I turn the H-Bridge off and if
> the current is too low, I turn it on.
>

I see a possible problem in the posted schematics. There are no
damping components on the current sense resistors. Also, these
resistors need to be non-inductive types. Generally a small RC
time constant is used to get rid of the inductive effects when the
power transistors switch. If the spikes cause the PIC to think
the current limit has been reached too early, the current will not
build up to the desired value.

> I am currently using ripple drive (only 1 coil at a time)
> in the stepper controller with a maximum current of 1 Amp
> through each coil.
>

Have you actually measured the 1 Amp current?

>
> 1) Increase the current to 2 amps.
>
>

Are your motors rated for 2 A? If so, then you do want to deliver rated
current
to the motors.

>
>

Jon