p44-stepper

This is a kernel module for driving stepper motors using GPIO outputs.

Using p44-stepper

after compiling/installing the p44-ledchain kernel module package, activate the driver as follows:

insmod p44-stepper stepper<Mno>=<activelow>,<type>,<coilA_gpio>,<coilB_gpio>,<coilC_gpio>,<coilD_gpio>

Where

Mno The stepper motor number to use. Can be 0..3.
activelow can be 0 for active high coil outputs, and 1 for inverted coil outputs.
type is the stepper motor type:
- 0 = unipolar: A/B are the coils of the first phase, C/D are the coils of the second phase. With steps (4 substeps per cycle, one half-coil always powered in each pair AB, CD)
- 1 = unipolar_hs: unipolar with half steps (8 substeps per cycle, intermediate steps with only one coil pair powered)
- All other values are reserved for other types in future versions of this driver
coilX_gpio: GPIO number for the coil connections A,B,C,D. A/B are the positive/negative subcoils of one phase, B/C positive/negative subcoils of the other phase.

So, the following command will create a driver for an unipolar motor on GPIOs 34...37 with active low outputs:

insmod p44-stepper stepper0=1,1,34,35,36,37

This will produce a /sys/class/stepper/stepper0 entry in the sysfs with the following files in it:

currentstep: the current step position. Can be set to a new value to re-adjust or zero the current position. Can be positive or negative withing int32 range. Writing also stops movement and sets targetstep to the same value
targetstep: the step position the motor should reach. Writing a new value starts movement
stepinterval: in microseconds: the step interval -> smaller values, higher speed
moving: 1 when in progress reaching currentstep==targetstep, 0 when stopped. Writing 0 also stops movement.
power: 1 when any coil has power. Writing 0 stops movement and removes power from all coils