Position reporting, refactored system variables, serial print fixes, updated streaming scripts.

- Added machine position reporting to status queries. This will be
further developed with part positioning/offsets and maintaining
location upon reset.

- System variables refactored into a global struct for better
readability.

- Removed old obsolete Ruby streaming scripts. These were no longer
compatible. Updated Python streaming scripts.

- Fixed printFloat() and other printing functions.

- Decreased planner buffer back to 18 blocks and increased TX serial
buffer to 64 bytes. Need the memory space for future developments.

- Begun adding run-time modes to grbl, where block delete toggle, mm/in
reporting modes, jog modes, etc can be set during runtime. Will be
fleshed out and placed into EEPROM when everything is added.

script/simple_stream.py

@@ -1,6 +1,15 @@
 #!/usr/bin/env python
 """\
 Simple g-code streaming script for grbl
+
+Provided as an illustration of the basic communication interface
+for grbl. When grbl has finished parsing the g-code block, it will
+return an 'ok' or 'error' response. When the planner buffer is full,
+grbl will not send a response until the planner buffer clears space.
+
+G02/03 arcs are special exceptions, where they inject short line 
+segments directly into the planner. So there may not be a response 
+from grbl for the duration of the arc.
 """
 
 import serial

script/stream.py

@@ -0,0 +1,80 @@
+#!/usr/bin/env python
+"""\
+Stream g-code to grbl controller
+
+This script differs from the simple_stream.py script by 
+tracking the number of characters in grbl's serial read
+buffer. This allows grbl to fetch the next line directly
+from the serial buffer and does not have to wait for a 
+response from the computer. This effectively adds another
+buffer layer to prevent buffer starvation.
+
+TODO: - Add runtime command capabilities
+
+Version: SKJ.20120104
+"""
+
+import serial
+import re
+import time
+import sys
+import argparse
+
+RX_BUFFER_SIZE = 128
+
+# Define command line argument interface
+parser = argparse.ArgumentParser(description='Stream g-code file to grbl. (pySerial library required)')
+parser.add_argument('gcode', type=argparse.FileType('r'),
+        help='g-code filename to be streamed')
+parser.add_argument('device',
+        help='serial device path')
+parser.add_argument('-q','--quiet',action='store_true', default=False, 
+        help='suppress output text')
+args = parser.parse_args()
+
+# Initialize
+s = serial.Serial(args.device_file,9600)
+f = args.gcode_file
+verbose = True
+if args.quiet : verbose = False
+
+# Wake up grbl
+print "Initializing grbl..."
+s.write("\r\n\r\n")
+
+# Wait for grbl to initialize and flush startup text in serial input
+time.sleep(2)
+s.flushInput()
+
+# Stream g-code to grbl
+print "Streaming ", args.gcode_file.name, " to ", args.device_file
+l_count = 0
+g_count = 0
+c_line = []
+for line in f:
+    l_count += 1 # Iterate line counter
+#     l_block = re.sub('\s|\(.*?\)','',line).upper() # Strip comments/spaces/new line and capitalize
+    l_block = line.strip()
+    c_line.append(len(l_block)) # Track number of characters in grbl serial read buffer
+    grbl_out = '' 
+    while sum(c_line) >= RX_BUFFER_SIZE-1 | s.inWaiting() :
+        out_temp = s.readline().strip() # Wait for grbl response
+        if out_temp not in ['ok','error'] :
+            print "  Debug: ",out_temp # Debug response
+        else :
+            grbl_out += out_temp;
+            g_count += 1 # Iterate g-code counter
+            grbl_out += str(g_count); # Add line finished indicator
+            del c_line[0]
+    if verbose: print "SND: " + str(l_count) + " : " + l_block,
+    s.write(l_block + '\n') # Send block to grbl
+    if verbose : print "BUF:",str(sum(c_line)),"REC:",grbl_out
+
+# Wait for user input after streaming is completed
+print "G-code streaming finished!\n"
+print "WARNING: Wait until grbl completes buffered g-code blocks before exiting."
+raw_input("  Press <Enter> to exit and disable grbl.") 
+
+# Close file and serial port
+f.close()
+s.close()