18f4431; driving a stepper IN HARDWARE mode

[Bill Legge]

Thanks for the thread - please keep posting your progress.

There is an excellent application note on the problem of ramping up/down on:

The ATMEL site: AVR446 'Linear Control of Stepper Motor'

It comes up with a good approximation for linear acceleration without over-taxing the MCU. The simple business of making linear changes to the PWM 'sort of works' but is nothing like the smooth motion one get with MACH3.

Regards Bill Legge

[DDDvvv]

thanks for the atmel app note. i've also been thinking about the trapezoid curves, and since all cnc software incorporate them, there's no need to take the trouble for them, unless one wants to control the stepper from serial/parallel, or standalone.
i have a crude power driver on a bread board, and still experimenting on pwm chopping to limit the current. anyone know what's a good pulse frequency for chopping? i've been adjusting it around, ive tried frequencies between 5khz to 56 khz. conclusion; higher frequencies cause more heat dissipation on the power transistors, (which are not heatsinked).

if i can get this pwm to limit/control current, then ill be happy.

thanks for the idea, and back to experimenting.

regards