PicoMite MMBasic — Stepper Motor Control Reference

PicoMite MMBasic — Stepper Motor Control Reference

PicoMite Stepper Motor Control Reference 1. Overview The STEPPER command provides a comprehensive system for controlling up to 3 stepper motor axes (X, Y, Z) with support for G-code execution, acceleration planning, and hardware limit switches. It uses a dedicated 100kHz interrupt timer for smooth pulse generation. 2. Initialization & Configuration 2.1 Initialization STEPPER INIT [arc_tolerance] [,buffer_size] [,estop_pin] [,estop_keep_enabled] Initializes the stepper subsystem. Must be called before any other STEPPER commands. - arc_tolerance: (Optional) Tolerance for arc segmentation in mm (default: 0.05). - buffer_size: (Optional) Size of the G-code lookahead buffer (default: 32, max: 1024). - estop_pin: (Optional) Hardware emergency-stop input pin (active low). - estop_keep_enabled: (Optional) 0 (default) = disable drivers on E-STOP, 1 = keep drivers enabled on E-STOP. 2.2 Axis Configuration STEPPER AXIS axis, step_pin, dir_pin [, enable_pin] [, dir_invert] [, steps_per_mm] [, max_vel] [, max_accel] [, home_backoff_mm] Configures a specific axis (X, Y, or Z). - axis: X, Y, or Z. - step_pin/dir_pin: GPIO pins for Step and Direction signals. - enable_pin: (Optional) GPIO pin for Enable signal (active low). - dir_invert: (Optional) 1 to invert direction, 0 otherwise. - steps_per_mm: (Optional) Steps required to move 1mm. - max_vel: (Optional) Maximum velocity in mm/min. - max_accel: (Optional) Maximum acceleration in mm/s^2. - home_backoff_mm: (Optional) Homing switch clear/backoff distance in mm (default: 3.0). 2.3 Limits & Safety STEPPER HWLIMITS x_min, y_min, z_min [,x_max] [,y_max] [,z_max] Configures hardware limit switch pins (active low). Pins must be mutually AXIS/SPINDLE/E-STOP, except min and max may share the same pin on the same axis. exclusive with STEPPER LIMITS axis, min_mm, max_mm Sets soft limits for an axis in mm. STEPPER ESTOP Software emergency stop: halts motion immediately, clears buffer, and turns spindle off. Drivers are disabled unless estop_keep_enabled was set to 1 in STEPPER INIT. If an INIT estop_pin is configured, hardware E-STOP is monitored in ISR and terminates processing Page 1 PicoMite Stepper Motor Control Reference immediately under all circumstances (including homing). 3. Motion Control 3.1 G-Code Execution STEPPER GC <gcode> [words...] Executes a standard G-code command string. Supported codes: G0, G1, G2, G3, G4, G28, G90, G91, G92, M3, M5. M3/M5 and G4 are buffered and executed in-order with motion blocks. G28 homes specified axes, or all configured axes if no axis words are supplied. Example: STEPPER GC G1 X10 Y5 F500 STEPPER GCODE G0|G1|G2|G3|G4|G28|G90|G91|G92|M3|M5 [, X, x] [, Y, y] [, Z, z] [, F, feed] [, I, i] [, J, j] [, K, k] [, R, r] [, P, ms] Alternative syntax for adding motion commands to the buffer. All parameters must be comma separated. G4 uses P in milliseconds (for example: STEPPER GCODE G4, P, 500). Example: STEPPER GCODE G1, X, 10, Y, 5, F, 500 3.2 Manual Positioning STEPPER POSITION HOME Sets all axes to position 0 and clears G92 offsets. STEPPER POSITION axis, position Sets the current position of an axis to the specified value (mm). 4. Advanced Features STEPPER SCURVE 0|1 Enables (1) or disables (0) S-curve acceleration profiling for smoother motion. STEPPER JERK value Sets the jerk limit in mm/s^3 for S-curve planning. STEPPER SPINDLE pin [,invert] Configures a spindle control pin used by buffered M3/M5 commands. Pin must not conflict with AXIS/HWLIMITS/E-STOP pins. 5. System Management STEPPER RUN [,0|1] Arms the system and begins executing buffered commands. Page 2 PicoMite Stepper Motor Control Reference Optional mode argument controls behavior when the queue drains: - 0 (default): remain armed with drivers enabled while idle. - 1: when idle and no buffered work remains, drivers are disabled and then re-enabled automatically when new queued work arrives. STEPPER CLEAR Clears the G-code buffer (only when motion is idle). STEPPER STATUS Displays detailed system status, including axis positions, buffer state, and configuration (including auto-disable-on-idle mode). STEPPER CLOSE Shuts down the stepper subsystem, releases resources, and deconfigures stepper-owned GPIO pins. PEEK(STEPPER X) PEEK(STEPPER Y) PEEK(STEPPER Z) PEEK(STEPPER ACTIVE) PEEK(STEPPER STATUS) PEEK(STEPPER BUFFER) Returns current workspace axis position in mm (X/Y/Z) or active state (ACTIVE returns 1 when stepper is actively processing queued work, 0 when idle, or -1 if the stepper subsystem has not been initialized). STATUS returns a bitmap of safety and coordinate state: - bit0: X_MIN limit asserted - bit1: X_MAX limit asserted - bit2: Y_MIN limit asserted - bit3: Y_MAX limit asserted - bit4: Z_MIN limit asserted - bit5: Z_MAX limit asserted - bit6: E-STOP asserted - bit7: position known (machine coordinates established). BUFFER returns the number of free slots in the G-code circular buffer. This can be used to throttle G-code submission and avoid overflowing the buffer. Page 3