Dear All,

=A0
I haven=92t been designing my own stepper motor drivers since the days of t=
he L297+L298 but now I find myself in the need of a stepper motor driver ci=
rcuit and I=92m hoping someone on the PIClist can help point me in the righ=
t direction.

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We have been using many commercial stepper motor controllers with all kinds=
 of bells and whistles (micro-stepping, speed ramp-up/down, stall detection=
, selectable currents, =85) so we know what is possible but this time we ne=
ed to build such a driver/controller ourselves:

=A0
For one of our new products we plan to use a small stepper motor with a lea=
d screw for low speed (<200 RPM) precision positioning. The stepper motor c=
ontroller needs to be integrated into the product and should respond to a f=
orward pushbutton and a reverse pushbutton and to positioning commands thro=
ugh a digital interface.

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We have a 12 Volt power supply available. The stepper motor is available in=
 3 Volt, 6 Volt or 12 Volt (with nominal currents of 0.22A, 0.11A or 0.055A=
 respectively). We need limit switches on both ends. We have an FPGA that c=
an program the driver IC with any settings by SPI or other interface.

=A0
We need to have small size, micro-stepping, speed ramp-up/down and digital =
control/position readout. Stall detection is not necessary. Selectable curr=
ent, low idle current and overall low power consumption/heat generation is =
preferred (switched-mode power supply/pwm drive?). Cost is less of an issue=
..=20

=A0
Does anyone have any suggestions on what device we could use ? Is an SMD op=
tical transmissive sensor the best small size solution for a precision home=
/limit switch ?

=A0
All help is much appreciated.

=A0
Best regards,

=A0
Andries

=A0
=A0
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