successfully maintained 30khz, lots of optimization of code and buffering allocation

gcode.c

@@ -112,7 +112,7 @@ void select_plane(uint8_t axis_0, uint8_t axis_1, uint8_t axis_2)
 
 void gc_init() {
   memset(&gc, 0, sizeof(gc));
-  gc.feed_rate = DEFAULT_FEEDRATE;
+  gc.feed_rate = DEFAULT_FEEDRATE/60;
   select_plane(X_AXIS, Y_AXIS, Z_AXIS);
   gc.absolute_mode = true;
 }
@@ -209,7 +209,7 @@ uint8_t gc_execute_line(char *line) {
       if (gc.inverse_feed_rate_mode) {
         inverse_feed_rate = unit_converted_value; // seconds per motion for this motion only
       } else {
-        gc.feed_rate = unit_converted_value; // millimeters pr second
+        gc.feed_rate = unit_converted_value/60; // millimeters pr second
       }
       break;
       case 'I': case 'J': case 'K': offset[letter-'I'] = unit_converted_value; break;

motion_control.c

@@ -63,90 +63,38 @@ void mc_dwell(uint32_t milliseconds)
   mode = MC_MODE_AT_REST; 
 }
 
-// Calculate the microseconds between steps that we should wait in order to travel the 
-// designated amount of millimeters in the amount of steps we are going to generate
-void compute_and_set_step_pace(double feed_rate, double millimeters_of_travel, uint32_t steps, int invert) {
-  int32_t pace;
-  if (invert) {
-    pace = round(ONE_MINUTE_OF_MICROSECONDS/feed_rate/steps);
-  } else {
-    pace = round((ONE_MINUTE_OF_MICROSECONDS/X_STEPS_PER_MM)/feed_rate);
-  }
-  st_buffer_pace(pace);
-}
-
 // Execute linear motion in absolute millimeter coordinates. Feed rate given in millimeters/second
 // unless invert_feed_rate is true. Then the feed_rate means that the motion should be completed in
 // 1/feed_rate minutes.
 void mc_line(double x, double y, double z, float feed_rate, int invert_feed_rate)
 {
 	// Flags to keep track of which axes to step
+  uint8_t axis; // loop variable
   int32_t target[3]; // The target position in absolute steps
+  int32_t steps[3]; // The target line in relative steps
   
   // Setup ---------------------------------------------------------------------------------------------------
-  PORTD |= (1<<4);
-  PORTD |= (1<<5);
-  target[X_AXIS] = round(x*X_STEPS_PER_MM);
-  target[Y_AXIS] = round(y*Y_STEPS_PER_MM);
-  target[Z_AXIS] = round(z*Z_STEPS_PER_MM); 
-  PORTD ^= (1<<5);
-  // Determine direction and travel magnitude for each axis
-  for(axis = X_AXIS; axis <= Z_AXIS; axis++) {
-  	step_count[axis] = labs(target[axis] - position[axis]);
-    direction[axis] = signof(target[axis] - position[axis]);
-  }
-  PORTD ^= (1<<5);
-  // Find the magnitude of the axis with the longest travel
-	maximum_steps = max(step_count[Z_AXIS], 
-	  max(step_count[X_AXIS], step_count[Y_AXIS]));
-  PORTD ^= (1<<5);
-  // Nothing to do?
-  if (maximum_steps == 0) { PORTD &= ~(1<<4); PORTD |= (1<<5); return; }
-  PORTD ^= (1<<5);
-	// Set up a neat counter for each axis
-  for(axis = X_AXIS; axis <= Z_AXIS; axis++) {
-    counter[axis] = -maximum_steps/2;
-  }
-  PORTD ^= (1<<5);
-	// Set our direction pins 
-  set_stepper_directions(direction);
-  PORTD ^= (1<<5);
 
+  target[X_AXIS] = lround(x*X_STEPS_PER_MM);
+  target[Y_AXIS] = lround(y*Y_STEPS_PER_MM);
+  target[Z_AXIS] = lround(z*Z_STEPS_PER_MM); 
+
+  for(axis = X_AXIS; axis <= Z_AXIS; axis++) {
+    steps[axis] = target[axis]-position[axis];
+  }
+  
+	if (invert_feed_rate) {
+    st_buffer_line(steps[X_AXIS], steps[Y_AXIS], steps[Z_AXIS], lround(ONE_MINUTE_OF_MICROSECONDS/feed_rate));
+	} else {
   	// Ask old Phytagoras to estimate how many mm our next move is going to take us
-	double millimeters_of_travel = 
+  	double millimeters_of_travel = sqrt(
-    sqrt(square(X_STEPS_PER_MM*step_count[X_AXIS]) + 
+  	  square(steps[X_AXIS]/X_STEPS_PER_MM) + 
-        square(Y_STEPS_PER_MM*step_count[Y_AXIS]) + 
+  	  square(steps[Y_AXIS]/Y_STEPS_PER_MM) + 
-        square(Z_STEPS_PER_MM*step_count[Z_AXIS]));
+  	  square(steps[Z_AXIS]/Z_STEPS_PER_MM));
-      PORTD ^= (1<<5);
+    st_buffer_line(steps[X_AXIS], steps[Y_AXIS], steps[Z_AXIS],
-  // And set the step pace
+      lround((millimeters_of_travel/feed_rate)*1000000));
-  compute_and_set_step_pace(feed_rate, millimeters_of_travel, maximum_steps, invert_feed_rate);
-  PORTD &= ~(1<<5);
-  PORTD &= ~(1<<4);
-  
-  // Execution -----------------------------------------------------------------------------------------------
-
-  mode = MC_MODE_LINEAR;
-  
-  do {
-  	// Trace the line
-    step_bits = 0;
-    for(axis = X_AXIS; axis <= Z_AXIS; axis++) {
-  		if (target[axis] != position[axis])
-  		{
-  			counter[axis] += step_count[axis];
-  			if (counter[axis] > 0)
-  			{
-          step_bits |= st_bit_for_stepper(axis);
-  				counter[axis] -= maximum_steps;
-          position[axis] += direction[axis];
 	}
-  		}
+	memcpy(position, target, sizeof(target)); // position[] = target[] 
-  	}
-    if(step_bits) { 
-      step_steppers(step_bits);
-    }
-  } while (step_bits);
-  mode = MC_MODE_AT_REST;
 }
 
 
@@ -189,8 +137,3 @@ void set_stepper_directions(int8_t *direction)
     ((direction[Y_AXIS]&0x80)>>(7-Y_DIRECTION_BIT)) |
     ((direction[Z_AXIS]&0x80)>>(7-Z_DIRECTION_BIT)));
 }
-
-inline void step_steppers(uint8_t bits) 
-{
-  st_buffer_step(direction_bits | bits);
-}

script/stream.rb

@@ -29,7 +29,7 @@ SerialPort.open('/dev/tty.usbserial-A9007QcR', 9600) do |sp|
   sleep 5
   ARGV.each do |file|
     puts "Processing file #{file}"
-    prebuffer = $prebuffer ? 7 : 0
+    prebuffer = $prebuffer ? 12 : 0
     File.readlines(file).each do |line|
       next if line.strip == ''
       puts line.strip

stepper.c

@@ -25,6 +25,7 @@
 #include "stepper.h"
 #include "config.h"
 #include <math.h>
+#include <stdlib.h>
 #include <util/delay.h>
 #include "nuts_bolts.h"
 #include <avr/interrupt.h>
@@ -32,30 +33,30 @@
 #include "wiring_serial.h"
 
 #define TICKS_PER_MICROSECOND (F_CPU/1000000)
-#define LINE_BUFFER_SIZE 5
+#define LINE_BUFFER_SIZE 8
 
 struct Line {
   uint32_t steps_x, steps_y, steps_z;
-  uint32_t maximum_steps;
+  int32_t maximum_steps;
-  uint32_t iterations;
   uint8_t direction_bits;
   uint32_t rate;
-}
+};
 
-volatile uint8_t line_buffer[LINE_BUFFER_SIZE]; // A buffer for step instructions
+struct Line line_buffer[LINE_BUFFER_SIZE]; // A buffer for step instructions
 volatile int line_buffer_head = 0;
 volatile int line_buffer_tail = 0;
 
 // Variables used by SIG_OUTPUT_COMPARE1A
 uint8_t out_bits;
 struct Line *current_line;
-uint32_t counter_x, counter_y, counter_z;
+volatile int32_t counter_x, counter_y, counter_z;
+uint32_t iterations;
 
 uint8_t stepper_mode = STEPPER_MODE_STOPPED;
 
 void config_pace_timer(uint32_t microseconds);
 
-void st_buffer_line(int32_t steps_x, int32_t steps_y, int32_t steps_z, uint32_t rate) {
+void st_buffer_line(int32_t steps_x, int32_t steps_y, int32_t steps_z, uint32_t microseconds) {
   // Buffer nothing unless stepping subsystem is running
   if (stepper_mode != STEPPER_MODE_RUNNING) { return; }
   // Calculate the buffer head after we push this byte
@@ -68,18 +69,20 @@ void st_buffer_line(int32_t steps_x, int32_t steps_y, int32_t steps_z, uint32_t
   struct Line *line = &line_buffer[line_buffer_head];
   line->steps_x = labs(steps_x);
   line->steps_y = labs(steps_y);
-  line->steps_z = labs(steps_y);  
+  line->steps_z = labs(steps_z);  
   line->maximum_steps = max(line->steps_x, max(line->steps_y, line->steps_z));
-  line->iterations = line->maximum_steps;
+  // Bail if this is a zero-length line
-  line->rate = rate;
+  if (line->maximum_steps == 0) { return; };
+  line->rate = microseconds/line->maximum_steps;
   uint8_t direction_bits = 0;
   if (steps_x < 0) { direction_bits |= (1<<X_DIRECTION_BIT); }
   if (steps_y < 0) { direction_bits |= (1<<Y_DIRECTION_BIT); }
   if (steps_z < 0) { direction_bits |= (1<<Z_DIRECTION_BIT); }
   line->direction_bits = direction_bits;
-  
   // Move buffer head
   line_buffer_head = next_buffer_head;
+  // enable stepper interrupt
+	TIMSK1 |= (1<<OCIE1A);
 }
 
 // This timer interrupt is executed at the pace set with st_buffer_pace. It pops one instruction from
@@ -87,6 +90,7 @@ void st_buffer_line(int32_t steps_x, int32_t steps_y, int32_t steps_z, uint32_t
 // five microseconds.
 SIGNAL(SIG_OUTPUT_COMPARE1A)
 {
+  PORTD |= (1<<3);
   // Set the direction pins a cuple of nanoseconds before we step the steppers
   STEPPING_PORT = (STEPPING_PORT & ~DIRECTION_MASK) | (out_bits & DIRECTION_MASK);
   // Then pulse the stepping pins
@@ -96,16 +100,21 @@ SIGNAL(SIG_OUTPUT_COMPARE1A)
     
   // If there is no current line, attempt to pop one from the buffer
   if (current_line == NULL) {
+    PORTD &= ~(1<<4);
     // Anything in the buffer?
     if (line_buffer_head != line_buffer_tail) {
+      PORTD ^= (1<<5);
       // Retrieve a new line and get ready to step it
       current_line = &line_buffer[line_buffer_tail]; 
       config_pace_timer(current_line->rate);
-      counter_x = -current_line->maximum_steps/2;
+      counter_x = -(current_line->maximum_steps/2);
       counter_y = counter_x;
       counter_z = counter_x;
-      // move the line buffer tail to the next instruction
+      iterations = current_line->maximum_steps;
-      line_buffer_tail = (line_buffer_tail + 1) % LINE_BUFFER_SIZE;
+    } else {
+      // disable this interrupt until there is something to handle
+    	TIMSK1 &= ~(1<<OCIE1A);
+      PORTD |= (1<<4);          
     }    
   } 
 
@@ -127,14 +136,17 @@ SIGNAL(SIG_OUTPUT_COMPARE1A)
       counter_z -= current_line->maximum_steps;
     }
     // If current line is finished, reset pointer 
-    current_line->iterations -= 1;
+    iterations -= 1;
-    if (current_line->iterations <= 0) {
+    if (iterations <= 0) {
       current_line = NULL;
+      // move the line buffer tail to the next instruction
+      line_buffer_tail = (line_buffer_tail + 1) % LINE_BUFFER_SIZE;      
     }
   } else {
     out_bits = 0;
   }
   out_bits ^= STEPPING_INVERT_MASK;
+  PORTD &= ~(1<<3);  
 }
 
 // This interrupt is set up by SIG_OUTPUT_COMPARE1A when it sets the motor port bits. It resets
@@ -258,7 +270,6 @@ void config_pace_timer(uint32_t microseconds)
   TCCR1B = (TCCR1B & ~(0x07<<CS10)) | ((prescaler+1)<<CS10);
   // Set ceiling
   OCR1A = ceiling;
-  current_pace = microseconds;
 }
 
 int check_limit_switches()

wiring_serial.c

@@ -28,7 +28,7 @@
 // using a ring buffer (I think), in which rx_buffer_head is the index of the
 // location to which to write the next incoming character and rx_buffer_tail
 // is the index of the location from which to read.
-#define RX_BUFFER_SIZE 256
+#define RX_BUFFER_SIZE 200
 
 unsigned char rx_buffer[RX_BUFFER_SIZE];