stepper v0.1.0

Step/direction stepper driver for A4988 and DRV8825 modules.

Application scenarios

• A linear stage or lead screw.
• A pump or valve actuator.
• A small CNC or camera slider.

Contract

void stepper_init(stepper_t *motor, stepper_port_t port,
                  uint16_t full_steps_per_rev, uint8_t microsteps);
void stepper_set_speed(stepper_t *motor, uint16_t rpm);
void stepper_move(stepper_t *motor, int32_t microsteps);
void stepper_enable(stepper_t *motor, uint8_t enabled);

• stepper_move is blocking; positive steps move forward.
• stepper_set_speed computes the step period from RPM, full steps, and microsteps.
• position counts microsteps.
• The adapter drives STEP, DIR, and optional ENABLE.

Parameters

• A4988: 200 full steps/rev; microsteps 1, 2, 4, 8, 16.
• DRV8825: 200 full steps/rev; microsteps up to 32.
• Keep the STEP high time at least 1 us; this driver uses 2 us.
• Set the current limit before connecting the motor.

Memory and timing

• 16 bytes; blocking move; one delay per step.
• At 600 rpm with 200 steps and 1 microstep, the period is 500 us.

Integration

stepper_t motor;
stepper_init(&motor, board_stepper_port(), 200, 16);
stepper_set_speed(&motor, 60);
stepper_enable(&motor, 1);
stepper_move(&motor, 3200);

Adapters

• The adapter sets the microstep pins and the current limit.
• Reference: laurb9/StepperDriver (MIT) and the A4988/DRV8825 datasheets.
• This implementation is original.

When not to use

• Closed-loop position control; use an encoder and a servo controller.
• High-speed motion that needs acceleration; add a ramp.

Verification

make test covers direction, step count, period calculation, and enable.

void *context;
void (*set_step)(void *context, uint8_t level);
void (*set_direction)(void *context, uint8_t forward);
void (*set_enable)(void *context, uint8_t enabled);
void (*delay_us)(void *context, uint32_t microseconds);

stepper_port_t port;
uint16_t full_steps_per_rev;
uint8_t microsteps;
uint32_t step_interval_us;
int32_t position;