ManuelW/grbl-LPC-CoreXY
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eliminated an annoying constant that broke my cleanly layered abstractions

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Simen Svale Skogsrud 2011-01-14 16:56:44 +01:00
parent 49a16cb777
commit 0be21a9034
5 changed files with 60 additions and 48 deletions
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2
config.h
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@ -107,6 +107,8 @@ void store_setting(int parameter, double value);
// Or bake your own like this adding any step-bits or directions you want to invert:
// #define STEPPING_INVERT_MASK (STEP_MASK | (1<<X_DIRECTION_BIT) | (1<<Y_DIRECTION_BIT))
// The temporal resolution of the acceleration management subsystem
#define ACCELERATION_TICKS_PER_SECOND 10
// Some useful constants
#define STEP_MASK ((1<<X_STEP_BIT)|(1<<Y_STEP_BIT)|(1<<Z_STEP_BIT)) // All step bits

53
motion_plan.c
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@ -43,8 +43,8 @@ inline uint32_t estimate_acceleration_ticks(int32_t start_rate, int32_t accelera
// Calculates trapezoid parameters so that the entry- and exit-speed is compensated by the provided factors.
// In practice both factors must be in the range 0 ... 1.0
void calculate_trapezoid_for_block(struct Block *block, double entry_factor, double exit_factor) {
block->initial_rate = max(round(block->nominal_rate*entry_factor),MINIMAL_STEP_RATE);
int32_t final_rate = max(round(block->nominal_rate*entry_factor),MINIMAL_STEP_RATE);
block->initial_rate = round(block->nominal_rate*entry_factor);
int32_t final_rate = round(block->nominal_rate*entry_factor);
int32_t acceleration_per_second = block->rate_delta*ACCELERATION_TICKS_PER_SECOND;
int32_t acceleration_steps =
estimate_acceleration_distance(block->initial_rate, block->nominal_rate, acceleration_per_second);
@ -67,3 +67,52 @@ void calculate_trapezoid_for_block(struct Block *block, double entry_factor, dou
block->plateau_ticks = 0;
}
}
// Add a new linear movement to the buffer. steps_x, _y and _z is the signed, relative motion in
// steps. Microseconds specify how many microseconds the move should take to perform. To aid acceleration
// calculation the caller must also provide the physical length of the line in millimeters.
void mp_buffer_line(int32_t steps_x, int32_t steps_y, int32_t steps_z, uint32_t microseconds, double millimeters) {
// Calculate the buffer head after we push this byte
int next_buffer_head = (block_buffer_head + 1) % BLOCK_BUFFER_SIZE;
// If the buffer is full: good! That means we are well ahead of the robot.
// Rest here until there is room in the buffer.
while(block_buffer_tail == next_buffer_head) { sleep_mode(); }
// Prepare to set up new block
struct Block *block = &block_buffer[block_buffer_head];
// Number of steps for each axis
block->steps_x = labs(steps_x);
block->steps_y = labs(steps_y);
block->steps_z = labs(steps_z);
block->step_event_count = max(block->steps_x, max(block->steps_y, block->steps_z));
// Bail if this is a zero-length block
if (block->step_event_count == 0) { return; };
// Calculate speed in mm/minute for each axis
double multiplier = 60.0*1000000.0/microseconds;
block->speed_x = block->steps_x*multiplier/settings.steps_per_mm[0];
block->speed_y = block->steps_y*multiplier/settings.steps_per_mm[1];
block->speed_z = block->steps_z*multiplier/settings.steps_per_mm[2];
block->nominal_rate = round(block->step_event_count*multiplier);
// Compute the acceleration rate for the trapezoid generator. Depending on the slope of the line
// average travel per step event changes. For a line along one axis the travel per step event
// is equal to the travel/step in the particular axis. For a 45 degree line the steppers of both
// axes might step for every step event. Travel per step event is then sqrt(travel_x^2+travel_y^2).
// To generate trapezoids with contant acceleration between blocks the rate_delta must be computed
// specifically for each line to compensate for this phenomenon:
double travel_per_step = (1.0*millimeters)/block->step_event_count;
block->rate_delta = round(
(settings.acceleration/(60.0*ACCELERATION_TICKS_PER_SECOND))/ // acceleration mm/min per acceleration_tick
travel_per_step); // convert to: acceleration steps/min/acceleration_tick
calculate_trapezoid_for_block(block,0,0); // compute a default trapezoid
// Compute direction bits for this block
block->direction_bits = 0;
if (steps_x < 0) { block->direction_bits |= (1<<X_DIRECTION_BIT); }
if (steps_y < 0) { block->direction_bits |= (1<<Y_DIRECTION_BIT); }
if (steps_z < 0) { block->direction_bits |= (1<<Z_DIRECTION_BIT); }
// Move buffer head
block_buffer_head = next_buffer_head;
// Ensure that block processing is running by enabling The Stepper Driver Interrupt
ENABLE_STEPPER_DRIVER_INTERRUPT();
}

9
motion_plan.h
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@ -50,8 +50,11 @@ extern struct Block block_buffer[BLOCK_BUFFER_SIZE]; // A ring buffer for motion
extern volatile int block_buffer_head; // Index of the next block to be pushed
extern volatile int block_buffer_tail; // Index of the block to process now
// Calculates trapezoid parameters so that the entry- and exit-speed is compensated by the provided factors.
// In practice both factors must be in the range 0 ... 1.0
void calculate_trapezoid_for_block(struct Block *block, double entry_factor, double exit_factor);
// Add a new linear movement to the buffer. steps_x, _y and _z is the signed, relative motion in
// steps. Microseconds specify how many microseconds the move should take to perform. To aid acceleration
// calculation the caller must also provide the physical length of the line in millimeters.
// Do not call directly unless you are writing a motor driver. In current iteration this is called by
// st_buffer_line which also wakes up the stepper subsystem.
void mp_buffer_line(int32_t steps_x, int32_t steps_y, int32_t steps_z, uint32_t microseconds, double millimeters);
#endif

41
stepper.c
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@ -120,46 +120,7 @@ inline void trapezoid_generator_tick() {
// steps. Microseconds specify how many microseconds the move should take to perform. To aid acceleration
// calculation the caller must also provide the physical length of the line in millimeters.
void st_buffer_line(int32_t steps_x, int32_t steps_y, int32_t steps_z, uint32_t microseconds, double millimeters) {
// Calculate the buffer head after we push this byte
int next_buffer_head = (block_buffer_head + 1) % BLOCK_BUFFER_SIZE;
// If the buffer is full: good! That means we are well ahead of the robot.
// Rest here until there is room in the buffer.
while(block_buffer_tail == next_buffer_head) { sleep_mode(); }
// Prepare to set up new block
struct Block *block = &block_buffer[block_buffer_head];
// Number of steps for each axis
block->steps_x = labs(steps_x);
block->steps_y = labs(steps_y);
block->steps_z = labs(steps_z);
block->step_event_count = max(block->steps_x, max(block->steps_y, block->steps_z));
// Bail if this is a zero-length block
if (block->step_event_count == 0) { return; };
// Calculate speed in mm/minute for each axis
double multiplier = 60.0*1000000.0/microseconds;
block->speed_x = block->steps_x*multiplier/settings.steps_per_mm[0];
block->speed_y = block->steps_y*multiplier/settings.steps_per_mm[1];
block->speed_z = block->steps_z*multiplier/settings.steps_per_mm[2];
block->nominal_rate = max(round(block->step_event_count*multiplier), MINIMAL_STEP_RATE);
// Compute the acceleration rate for the trapezoid generator. Depending on the slope of the line
// average travel per step event changes. For a line along one axis the travel per step event
// is equal to the travel/step in the particular axis. For a 45 degree line the steppers of both
// axes might step for every step event. Travel per step event is then sqrt(travel_x^2+travel_y^2).
// To generate trapezoids with contant acceleration between blocks the rate_delta must be computed
// specifically for each line to compensate for this phenomenon:
double travel_per_step = (1.0*millimeters)/block->step_event_count;
block->rate_delta = round(
(settings.acceleration/(60.0*ACCELERATION_TICKS_PER_SECOND))/ // acceleration mm/min per acceleration_tick
travel_per_step); // convert to: acceleration steps/min/acceleration_tick
calculate_trapezoid_for_block(block,0,0); // compute a default trapezoid
// Compute direction bits for this block
block->direction_bits = 0;
if (steps_x < 0) { block->direction_bits |= (1<<X_DIRECTION_BIT); }
if (steps_y < 0) { block->direction_bits |= (1<<Y_DIRECTION_BIT); }
if (steps_z < 0) { block->direction_bits |= (1<<Z_DIRECTION_BIT); }
// Move buffer head
block_buffer_head = next_buffer_head;
mp_buffer_line(steps_x, steps_y, steps_z, microseconds, millimeters);
// Ensure that block processing is running by enabling The Stepper Driver Interrupt
ENABLE_STEPPER_DRIVER_INTERRUPT();
}

3
stepper.h
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@ -24,9 +24,6 @@
#include <avr/io.h>
#include <avr/sleep.h>
#define ACCELERATION_TICKS_PER_SECOND 10
#define MINIMAL_STEP_RATE (ACCELERATION_TICKS_PER_SECOND*5)
// Initialize and start the stepper motor subsystem
void st_init();