Minor bug fixes and updates. Line number tracking.

- Line number tracking was getting truncated at 255, since it was using
wrong variable type. Fixed it with a trunc().

- Increased the max number line allowed by Grbl to 9999999 from the
g-code standard 99999. The latter seems to be an arbitrary number, so
we are allowing larger ones for at least one known use case scenario.

- Created a new test directory to contain some testing g-code to proof
the firmware. Only got started with one test case so far. More will be
inserted as needed.

- Some other commenting updates to clarify certain aspects of the code.

gcode.c

@@ -29,7 +29,10 @@
 #include "probe.h"
 #include "report.h"
 
-#define MAX_LINE_NUMBER 99999
+// NOTE: Max line number is defined by the g-code standard to be 99999. It seems to be an
+// arbitrary value, and some GUIs may require more. So we increased it based on a max safe
+// value when converting a float (7.2 digit precision)s to an integer.
+#define MAX_LINE_NUMBER 9999999 
 
 #define AXIS_COMMAND_NONE 0
 #define AXIS_COMMAND_NON_MODAL 1 
@@ -91,8 +94,8 @@ uint8_t gc_execute_line(char *line)
   memcpy(&gc_block.modal,&gc_state.modal,sizeof(gc_modal_t)); // Copy current modes
   uint8_t axis_explicit = AXIS_COMMAND_NONE;
   uint8_t axis_0, axis_1, axis_linear;
-  float coordinate_data[N_AXIS];
-  float parameter_data[N_AXIS];
+  float coordinate_data[N_AXIS]; // Multi-use variable to store coordinate data for execution
+  float parameter_data[N_AXIS]; // Multi-use variable to store parameter data for execution
   
   // Initialize bitflag tracking variables for axis indices compatible operations.
   uint8_t axis_words = 0; // XYZ tracking
@@ -305,7 +308,7 @@ uint8_t gc_execute_line(char *line)
           case 'J': word_bit = WORD_J; gc_block.values.ijk[Y_AXIS] = value; ijk_words |= (1<<Y_AXIS); break;
           case 'K': word_bit = WORD_K; gc_block.values.ijk[Z_AXIS] = value; ijk_words |= (1<<Z_AXIS); break;
           case 'L': word_bit = WORD_L; gc_block.values.l = int_value; break;
-          case 'N': word_bit = WORD_N; gc_block.values.n = int_value; break;
+          case 'N': word_bit = WORD_N; gc_block.values.n = trunc(value); break;
           case 'P': word_bit = WORD_P; gc_block.values.p = value; break;
           // NOTE: For certain commands, P value must be an integer, but none of these commands are supported.
           // case 'Q': // Not supported
@@ -737,16 +740,20 @@ uint8_t gc_execute_line(char *line)
                 if (ijk_words & bit(idx)) { gc_block.values.ijk[idx] *= MM_PER_INCH; }
               }
             }         
-          
+
+            // Arc radius from center to target
             x -= gc_block.values.ijk[axis_0]; // Delta x between circle center and target
             y -= gc_block.values.ijk[axis_1]; // Delta y between circle center and target
-            float target_r = hypot_f(x,y);
-            gc_block.values.r = hypot_f(gc_block.values.ijk[axis_0], gc_block.values.ijk[axis_1]); // Compute arc radius for mc_arc
+            float target_r = hypot_f(x,y); 
+
+            // Compute arc radius for mc_arc. Defined from current location to center.
+            gc_block.values.r = hypot_f(gc_block.values.ijk[axis_0], gc_block.values.ijk[axis_1]); 
             
-            target_r = fabs(target_r-gc_block.values.r);
-            if (target_r > 0.005) { 
-              if (target_r > 0.5) { FAIL(STATUS_GCODE_INVALID_TARGET); } // [Arc definition error]
-              if (target_r > 0.001*gc_block.values.r) { FAIL(STATUS_GCODE_INVALID_TARGET); } // [Arc definition error]
+            // Compute difference between current location and target radii for final error-checks.
+            float delta_r = fabs(target_r-gc_block.values.r);
+            if (delta_r > 0.005) { 
+              if (delta_r > 0.5) { FAIL(STATUS_GCODE_INVALID_TARGET); } // [Arc definition error] > 0.5mm
+              if (delta_r > (0.001*gc_block.values.r)) { FAIL(STATUS_GCODE_INVALID_TARGET); } // [Arc definition error] > 0.005mm AND 0.1% radius
             }
           }
           break;

nuts_bolts.c

@@ -151,6 +151,7 @@ uint8_t get_direction_mask(uint8_t axis_idx)
   return(axis_mask);
 }
 
+
 float hypot_f(float x, float y)
 {
    return(sqrt(x*x + y*y));

protocol.c

@@ -61,7 +61,7 @@ static void protocol_execute_line(char *line)
 
 
 /* 
-  GRBL MAIN LOOP:
+  GRBL PRIMARY LOOP:
 */
 void protocol_main_loop()
 {
@@ -81,9 +81,9 @@ void protocol_main_loop()
     system_execute_startup(line); // Execute startup script.
   }
     
-  // ------------------------------------------------------------------------------  
-  // Main loop! Upon a system abort, this exits back to main() to reset the system. 
-  // ------------------------------------------------------------------------------  
+  // ---------------------------------------------------------------------------------  
+  // Primary loop! Upon a system abort, this exits back to main() to reset the system. 
+  // ---------------------------------------------------------------------------------  
   
   uint8_t iscomment = false;
   uint8_t char_counter = 0;
@@ -92,6 +92,14 @@ void protocol_main_loop()
 
     // Process one line of incoming serial data, as the data becomes available. Performs an
     // initial filtering by removing spaces and comments and capitalizing all letters.
+    
+    // NOTE: While comment, spaces, and block delete(if supported) handling should technically 
+    // be done in the g-code parser, doing it here helps compress the incoming data into Grbl's
+    // line buffer, which is limited in size. The g-code standard actually states a line can't
+    // exceed 256 characters, but the Arduino Uno does not have the memory space for this.
+    // With a better processor, it would be very easy to pull this initial parsing out as a 
+    // seperate task to be shared by the g-code parser and Grbl's system commands.
+    
     while((c = serial_read()) != SERIAL_NO_DATA) {
       if ((c == '\n') || (c == '\r')) { // End of line reached
         line[char_counter] = 0; // Set string termination character.

test/test.py

@@ -0,0 +1,25 @@
+import random
+import serial
+import time
+ser = serial.Serial('/dev/tty.usbmodem24111', 115200, timeout=0.001)
+time.sleep(1)
+outstanding = 0
+data = ''
+while True:
+    time.sleep(0.1)
+    data += ser.read()
+    pos = data.find('\n')
+    if pos == -1:
+        line = ''
+    else:
+        line = data[0:pos + 1]
+        data = data[pos + 1:]
+    if line == '' and outstanding < 3:
+        while outstanding < 3:
+            ser.write("G0 Z%0.3f\n" % (0.01 * (random.random() - 0.5)))
+            #ser.write("M3\n")
+            outstanding += 1
+        continue
+    if line == 'ok\r\n':
+        outstanding -= 1
+    print outstanding, repr(line.rstrip())