Tweaks. Seek rate updates when set. CCW arc full circle fix.

- Fixed a minor issue where the seek rates would not immediately be
used and only would after a reset. Should update live now.

- A full circle IJ offset CCW arc would not do anything. Fixed bug via
a simple if-then statement.

- Radius mode tweaks to check for negative value in sqrt() rather than
isnan() it. Error report updated to indicate what actually happened.

gcode.c

@@ -52,7 +52,7 @@ void gc_init()
 {
   memset(&gc, 0, sizeof(gc));
   gc.feed_rate = settings.default_feed_rate; // Should be zero at initialization.
-  gc.seek_rate = settings.default_seek_rate;
+//  gc.seek_rate = settings.default_seek_rate;
   select_plane(X_AXIS, Y_AXIS, Z_AXIS);
   gc.absolute_mode = true;
   
@@ -323,14 +323,14 @@ uint8_t gc_execute_line(char *line)
             target[i] = gc.position[i];
           }
         }
-        mc_line(target[X_AXIS], target[Y_AXIS], target[Z_AXIS], gc.seek_rate, false);
+        mc_line(target[X_AXIS], target[Y_AXIS], target[Z_AXIS], settings.default_seek_rate, false);
       }
       // Retreive G28/30 go-home position data (in machine coordinates) from EEPROM
       float coord_data[N_AXIS];
       uint8_t home_select = SETTING_INDEX_G28;
       if (non_modal_action == NON_MODAL_GO_HOME_1) { home_select = SETTING_INDEX_G30; }
       if (!settings_read_coord_data(home_select,coord_data)) { return(STATUS_SETTING_READ_FAIL); }
-      mc_line(coord_data[X_AXIS], coord_data[Y_AXIS], coord_data[Z_AXIS], gc.seek_rate, false); 
+      mc_line(coord_data[X_AXIS], coord_data[Y_AXIS], coord_data[Z_AXIS], settings.default_seek_rate, false); 
       axis_words = 0; // Axis words used. Lock out from motion modes by clearing flags.
       break;
     case NON_MODAL_SET_HOME_0: case NON_MODAL_SET_HOME_1:
@@ -400,7 +400,7 @@ uint8_t gc_execute_line(char *line)
         break;
       case MOTION_MODE_SEEK:
         if (!axis_words) { FAIL(STATUS_INVALID_STATEMENT);} 
-        else { mc_line(target[X_AXIS], target[Y_AXIS], target[Z_AXIS], gc.seek_rate, false); }
+        else { mc_line(target[X_AXIS], target[Y_AXIS], target[Z_AXIS], settings.default_seek_rate, false); }
         break;
       case MOTION_MODE_LINEAR:
         // TODO: Inverse time requires F-word with each statement. Need to do a check. Also need
@@ -474,10 +474,12 @@ uint8_t gc_execute_line(char *line)
             float y = target[gc.plane_axis_1]-gc.position[gc.plane_axis_1];
             
             clear_vector(offset);
-            float h_x2_div_d = -sqrt(4 * r*r - x*x - y*y)/hypot(x,y); // == -(h * 2 / d)
-            // If r is smaller than d, the arc is now traversing the complex plane beyond the reach of any
-            // real CNC, and thus - for practical reasons - we will terminate promptly:
-            if(isnan(h_x2_div_d)) { FAIL(STATUS_FLOATING_POINT_ERROR); return(gc.status_code); }
+            // First, use h_x2_div_d to compute 4*h^2 to check if it is negative or r is smaller
+            // than d. If so, the sqrt of a negative number is complex and error out.
+            float h_x2_div_d = 4 * r*r - x*x - y*y;
+            if (h_x2_div_d < 0) { FAIL(STATUS_ARC_RADIUS_ERROR); return(gc.status_code); }
+            // Finish computing h_x2_div_d.
+            h_x2_div_d = -sqrt(h_x2_div_d)/hypot(x,y); // == -(h * 2 / d)
             // Invert the sign of h_x2_div_d if the circle is counter clockwise (see sketch below)
             if (gc.motion_mode == MOTION_MODE_CCW_ARC) { h_x2_div_d = -h_x2_div_d; }
             

gcode.h

@@ -83,7 +83,7 @@ typedef struct {
   int8_t spindle_direction;        // 1 = CW, -1 = CCW, 0 = Stop {M3, M4, M5}
   uint8_t coolant_mode;            // 0 = Disable, 1 = Flood Enable {M8, M9}
   float feed_rate;                 // Millimeters/min
-  float seek_rate;                 // Millimeters/min - Can change depending on switches and such.
+//  float seek_rate;                 // Millimeters/min. Will be used in v0.9 when axis independence is installed
   float position[3];               // Where the interpreter considers the tool to be at this point in the code
   uint8_t tool;
 //  uint16_t spindle_speed;          // RPM/100

motion_control.c

@@ -105,8 +105,11 @@ void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8
   
   // CCW angle between position and target from circle center. Only one atan2() trig computation required.
   float angular_travel = atan2(r_axis0*rt_axis1-r_axis1*rt_axis0, r_axis0*rt_axis0+r_axis1*rt_axis1);
-  if (angular_travel < 0) { angular_travel += 2*M_PI; }
-  if (isclockwise) { angular_travel -= 2*M_PI; }
+  if (isclockwise) { // Correct atan2 output per direction
+    if (angular_travel >= 0) { angular_travel -= 2*M_PI; }
+  } else {
+    if (angular_travel <= 0) { angular_travel += 2*M_PI; }
+  }
   
   float millimeters_of_travel = hypot(angular_travel*radius, fabs(linear_travel));
   if (millimeters_of_travel == 0.0) { return; }

report.c

@@ -56,8 +56,8 @@ void report_status_message(uint8_t status_code)
       printPgmString(PSTR("Expected command letter")); break;
       case STATUS_UNSUPPORTED_STATEMENT:
       printPgmString(PSTR("Unsupported statement")); break;
-      case STATUS_FLOATING_POINT_ERROR:
-      printPgmString(PSTR("Float error")); break;
+      case STATUS_ARC_RADIUS_ERROR:
+      printPgmString(PSTR("Invalid radius")); break;
       case STATUS_MODAL_GROUP_VIOLATION:
       printPgmString(PSTR("Modal group violation")); break;
       case STATUS_INVALID_STATEMENT:

report.h

@@ -26,7 +26,7 @@
 #define STATUS_BAD_NUMBER_FORMAT 1
 #define STATUS_EXPECTED_COMMAND_LETTER 2
 #define STATUS_UNSUPPORTED_STATEMENT 3
-#define STATUS_FLOATING_POINT_ERROR 4
+#define STATUS_ARC_RADIUS_ERROR 4
 #define STATUS_MODAL_GROUP_VIOLATION 5
 #define STATUS_INVALID_STATEMENT 6
 #define STATUS_HARD_LIMIT 7