Merge branch 'master' of github.com:kliment/Printrun

printcore.py

@@ -20,7 +20,7 @@ from select import error as SelectError
 from threading import Thread, Lock
 from Queue import Queue, Empty as QueueEmpty
 import time, getopt, sys
-import platform, os, traceback
+import platform, os, traceback, errno
 import socket
 import re
 from functools import wraps
@@ -94,7 +94,8 @@ class printcore():
         self.xy_feedrate = None
         self.z_feedrate = None
         self.pronterface = None
-        
+
+    @locked
     def disconnect(self):
         """Disconnects from printer and pauses the print
         """
@@ -111,6 +112,8 @@ class printcore():
                 self.printer.close()
             except socket.error:
                 pass
+            except OSError:
+                pass
         self.printer = None
         self.online = False
         self.printing = False
@@ -208,6 +211,8 @@ class printcore():
             print "Can't read from printer (disconnected?) (Socket error {0}): {1}".format(e.errno, e.strerror)
             return None
         except OSError as e:
+            if e.errno == errno.EAGAIN: # Not a real error, no data was available
+                return ""
             print "Can't read from printer (disconnected?) (OS Error {0}): {1}".format(e.errno, e.strerror)
             return None
 
@@ -325,11 +330,12 @@ class printcore():
         if not gcode.lines:
             return True
         self.clear = False
-        self.print_thread = Thread(target = self._print)
+        resuming = (startindex != 0)
+        self.print_thread = Thread(target = self._print, kwargs = {"resuming": resuming})
         self.print_thread.start()
         return True
 
-    # run a simple script if it exists, no multithreading    
+    # run a simple script if it exists, no multithreading
     def runSmallScript(self, filename):
         if filename == None: return
         f = None
@@ -344,22 +350,22 @@ class printcore():
             l = l[:l.find(";")] #remove comment
             self.send_now(l)
           f.close()
-        
+
     def pause(self):
         """Pauses the print, saving the current position.
         """
         if not self.printing: return False
         self.paused = True
         self.printing = False
-        
+
         # try joining the print thread: enclose it in try/except because we might be calling it from the thread itself
         try:
           self.print_thread.join()
         except:
           pass
-        
+
         self.print_thread = None
-        
+
         # saves the status
         self.pauseX = self.analyzer.x-self.analyzer.xOffset;
         self.pauseY = self.analyzer.y-self.analyzer.yOffset;
@@ -375,7 +381,7 @@ class printcore():
         if self.paused:
           #restores the status
           self.send_now("G90") # go to absolute coordinates
-        
+
           xyFeedString = ""
           zFeedString = ""
           if self.xy_feedrate != None: xyFeedString = " F" + str(self.xy_feedrate)
@@ -384,11 +390,11 @@ class printcore():
           self.send_now("G1 X" + str(self.pauseX) + " Y" + str(self.pauseY) + xyFeedString)
           self.send_now("G1 Z" + str(self.pauseZ) + zFeedString)
           self.send_now("G92 E" + str(self.pauseE))
-        
+
           if self.pauseRelative: self.send_now("G91") # go back to relative if needed
           #reset old feed rate
           self.send_now("G1 F" + str(self.pauseF))
-        
+
         self.paused = False
         self.printing = True
         self.print_thread = Thread(target = self._print, kwargs = {"resuming": True})
@@ -449,7 +455,7 @@ class printcore():
             self.pronterface.pause(None)
           else:
             self.pause()
-            
+
     def _sendnext(self):
         if not self.printer:
             return
@@ -493,7 +499,7 @@ class printcore():
                 self.queueindex += 1
                 self.clear = True
                 return
-      
+
             tline = tline.split(";")[0]
             if len(tline) > 0:
                 self._send(tline, self.lineno, True)

printrun/gcview.py

@@ -32,6 +32,9 @@ from .gl.panel import wxGLPanel
 from .gl.trackball import trackball, mulquat, build_rotmatrix
 from .gl.libtatlin import actors
 
+from printrun_utils import imagefile, install_locale
+install_locale('pronterface')
+
 class GcodeViewPanel(wxGLPanel):
 
     def __init__(self, parent, id = wx.ID_ANY, build_dimensions = None, realparent = None):
@@ -189,6 +192,7 @@ class GcodeViewPanel(wxGLPanel):
     def fit(self):
         if not self.parent.model or not self.parent.model.loaded:
             return
+        self.canvas.SetCurrent(self.context)
         dims = self.parent.model.dims
         self.reset_mview(1.0)
         center_x = (dims[0][0] + dims[0][1]) / 2
@@ -199,6 +203,7 @@ class GcodeViewPanel(wxGLPanel):
             ratio = float(self.dist) / max(dims[0][2], dims[1][2])
             glScalef(ratio, ratio, 1)
         glTranslatef(center_x, center_y, 0)
+        wx.CallAfter(self.Refresh)
 
     def keypress(self, event):
         """gets keypress events and moves/rotates acive shape"""
@@ -219,9 +224,9 @@ class GcodeViewPanel(wxGLPanel):
             self.layerdown()
         x, y, _ = self.mouse_to_3d(self.width / 2, self.height / 2)
         if key in kzi:
-            self.zoom(step, (x, y))
+            self.zoom_to_center(step)
         if key in kzo:
-            self.zoom(1 / step, (x, y))
+            self.zoom_to_center(1 / step)
         if key in kfit:
             self.fit()
         if key in kshowcurrent:
@@ -229,9 +234,13 @@ class GcodeViewPanel(wxGLPanel):
                 return
             self.parent.model.only_current = not self.parent.model.only_current
         if key in kreset:
-            self.reset_mview(0.9)
-            self.basequat = [0, 0, 0, 1]
+            self.resetview()
         event.Skip()
+
+    def resetview(self):
+        self.canvas.SetCurrent(self.context)
+        self.reset_mview(0.9)
+        self.basequat = [0, 0, 0, 1]
         wx.CallAfter(self.Refresh)
 
 class GCObject(object):
@@ -300,7 +309,30 @@ class GcodeViewFrame(wx.Frame):
         else:
             self.model = None
         self.objects = [GCObject(self.platform), GCObject(None)]
-        self.glpanel = GcodeViewPanel(self, build_dimensions = build_dimensions)
+        panel = wx.Panel(self, -1)
+        self.glpanel = GcodeViewPanel(panel, build_dimensions = build_dimensions,
+                                      realparent = self)
+        vbox = wx.BoxSizer(wx.VERTICAL)
+        toolbar = wx.ToolBar(panel, -1, style = wx.TB_HORIZONTAL | wx.NO_BORDER | wx.TB_HORZ_TEXT)
+        toolbar.AddSimpleTool(1, wx.Image(imagefile('zoom_in.png'), wx.BITMAP_TYPE_PNG).ConvertToBitmap(), _("Zoom In [+]"), '')
+        toolbar.AddSimpleTool(2, wx.Image(imagefile('zoom_out.png'), wx.BITMAP_TYPE_PNG).ConvertToBitmap(), _("Zoom Out [-]"), '')
+        toolbar.AddSeparator()
+        toolbar.AddSimpleTool(3, wx.Image(imagefile('arrow_up.png'), wx.BITMAP_TYPE_PNG).ConvertToBitmap(), _("Move Up a Layer [U]"), '')
+        toolbar.AddSimpleTool(4, wx.Image(imagefile('arrow_down.png'), wx.BITMAP_TYPE_PNG).ConvertToBitmap(), _("Move Down a Layer [D]"), '')
+        toolbar.AddLabelTool(5, " " + _("Reset view"), wx.Image(imagefile('reset.png'), wx.BITMAP_TYPE_PNG).ConvertToBitmap(), shortHelp = _("Reset view [R]"), longHelp = '')
+        toolbar.AddLabelTool(6, " " + _("Fit to plate"), wx.Image(imagefile('fit.png'), wx.BITMAP_TYPE_PNG).ConvertToBitmap(), shortHelp = _("Fit to plate [F]"), longHelp = '')
+        toolbar.Realize()
+        self.toolbar = toolbar
+        vbox.Add(toolbar, 0, border = 5)
+        vbox.Add(self.glpanel, 1, wx.EXPAND)
+        panel.SetSizer(vbox)
+        self.Bind(wx.EVT_TOOL, lambda x: self.glpanel.zoom_to_center(1.2), id = 1)
+        self.Bind(wx.EVT_TOOL, lambda x: self.glpanel.zoom_to_center(1/1.2), id = 2)
+        self.Bind(wx.EVT_TOOL, lambda x: self.glpanel.layerup(), id = 3)
+        self.Bind(wx.EVT_TOOL, lambda x: self.glpanel.layerdown(), id = 4)
+        self.Bind(wx.EVT_TOOL, lambda x: self.glpanel.resetview(), id = 5)
+        self.Bind(wx.EVT_TOOL, lambda x: self.glpanel.fit(), id = 6)
+
 
     def set_current_gline(self, gline):
         if gline.is_move and self.model and self.model.loaded:

printrun/gl/panel.py

@@ -199,3 +199,8 @@ class wxGLPanel(wx.Panel):
         if to:
             glTranslatef(-delta_x, -delta_y, 0)
         wx.CallAfter(self.Refresh)
+
+    def zoom_to_center(self, factor):
+        self.canvas.SetCurrent(self.context)
+        x, y, _ = self.mouse_to_3d(self.width / 2, self.height / 2)
+        self.zoom(factor, (x, y))

printrun/gui.py

@@ -44,6 +44,15 @@ def make_sized_button(*args):
 def make_autosize_button(*args):
     return make_button(*args, size = (-1, buttonSize[1]), style = wx.BU_EXACTFIT)
 
+def make_custom_button(root, parentpanel, i):
+    btn = make_button(parentpanel, i.label, root.procbutton, i.tooltip)
+    btn.SetBackgroundColour(i.background)
+    btn.SetForegroundColour("black")
+    btn.properties = i
+    root.btndict[i.command] = btn
+    root.printerControls.append(btn)
+    return btn
+
 class XYZControlsSizer(wx.GridBagSizer):
 
     def __init__(self, root, parentpanel = None):
@@ -67,12 +76,12 @@ def add_extra_controls(self, root, parentpanel, extra_buttons = None):
         self.Add(root.monitorbox, pos = (base_line + 1, 5))
     root.monitorbox.Bind(wx.EVT_CHECKBOX, root.setmonitor)
 
-    self.Add(wx.StaticText(parentpanel,-1, _("Heat:")), pos = (base_line + 0, 0), span = (1, 1), flag = wx.ALIGN_CENTER_VERTICAL|wx.ALIGN_RIGHT)
+    self.Add(wx.StaticText(parentpanel,-1, _("Heat:")), pos = (base_line + 0, 0), span = (1, 2), flag = wx.ALIGN_CENTER_VERTICAL|wx.ALIGN_RIGHT)
     htemp_choices = [root.temps[i]+" ("+i+")" for i in sorted(root.temps.keys(), key = lambda x:root.temps[x])]
 
-    root.settoff = make_button(parentpanel, _("Off"), lambda e: root.do_settemp("off"), _("Switch Hotend Off"), size = (36,-1), style = wx.BU_EXACTFIT)
+    root.settoff = make_button(parentpanel, _("Off"), lambda e: root.do_settemp("off"), _("Switch Hotend Off"), size = (38,-1), style = wx.BU_EXACTFIT)
     root.printerControls.append(root.settoff)
-    self.Add(root.settoff, pos = (base_line + 0, 1), span = (1, 1))
+    self.Add(root.settoff, pos = (base_line + 0, 2), span = (1, 1))
 
     if root.settings.last_temperature not in map(float, root.temps.values()):
         htemp_choices = [str(root.settings.last_temperature)] + htemp_choices
@@ -81,17 +90,17 @@ def add_extra_controls(self, root, parentpanel, extra_buttons = None):
     root.htemp.SetToolTip(wx.ToolTip("Select Temperature for Hotend"))
     root.htemp.Bind(wx.EVT_COMBOBOX, root.htemp_change)
 
-    self.Add(root.htemp, pos = (base_line + 0, 2), span = (1, 2))
+    self.Add(root.htemp, pos = (base_line + 0, 3), span = (1, 1))
     root.settbtn = make_button(parentpanel, _("Set"), root.do_settemp, _("Switch Hotend On"), size = (38, -1), style = wx.BU_EXACTFIT)
     root.printerControls.append(root.settbtn)
     self.Add(root.settbtn, pos = (base_line + 0, 4), span = (1, 1))
 
-    self.Add(wx.StaticText(parentpanel,-1, _("Bed:")), pos = (base_line + 1, 0), span = (1, 1), flag = wx.ALIGN_CENTER_VERTICAL|wx.ALIGN_RIGHT)
+    self.Add(wx.StaticText(parentpanel,-1, _("Bed:")), pos = (base_line + 1, 0), span = (1, 2), flag = wx.ALIGN_CENTER_VERTICAL|wx.ALIGN_RIGHT)
     btemp_choices = [root.bedtemps[i]+" ("+i+")" for i in sorted(root.bedtemps.keys(), key = lambda x:root.temps[x])]
 
-    root.setboff = make_button(parentpanel, _("Off"), lambda e:root.do_bedtemp("off"), _("Switch Heated Bed Off"), size = (36,-1), style = wx.BU_EXACTFIT)
+    root.setboff = make_button(parentpanel, _("Off"), lambda e:root.do_bedtemp("off"), _("Switch Heated Bed Off"), size = (38,-1), style = wx.BU_EXACTFIT)
     root.printerControls.append(root.setboff)
-    self.Add(root.setboff, pos = (base_line + 1, 1), span = (1, 1))
+    self.Add(root.setboff, pos = (base_line + 1, 2), span = (1, 1))
 
     if root.settings.last_bed_temperature not in map(float, root.bedtemps.values()):
         btemp_choices = [str(root.settings.last_bed_temperature)] + btemp_choices
@@ -99,7 +108,7 @@ def add_extra_controls(self, root, parentpanel, extra_buttons = None):
             choices = btemp_choices, style = wx.CB_DROPDOWN, size = (80,-1))
     root.btemp.SetToolTip(wx.ToolTip("Select Temperature for Heated Bed"))
     root.btemp.Bind(wx.EVT_COMBOBOX, root.btemp_change)
-    self.Add(root.btemp, pos = (base_line + 1, 2), span = (1, 2))
+    self.Add(root.btemp, pos = (base_line + 1, 3), span = (1, 1))
 
     root.setbbtn = make_button(parentpanel, _("Set"), root.do_bedtemp, ("Switch Heated Bed On"), size = (38, -1), style = wx.BU_EXACTFIT)
     root.printerControls.append(root.setbbtn)
@@ -125,21 +134,31 @@ def add_extra_controls(self, root, parentpanel, extra_buttons = None):
         root.htemp.SetValue(root.htemp.Value + ' (user)')
 
     root.tempdisp = wx.StaticText(parentpanel,-1, "")
-
-    root.edist = wx.SpinCtrl(parentpanel,-1, "5", min = 0, max = 1000, size = (70,-1))
+   
+    if not extra_buttons:
+        ebuttonspanel = root.newPanel(parentpanel)
+        ebuttonssizer = wx.BoxSizer(wx.HORIZONTAL)
+        ebuttonspanel.SetSizer(ebuttonssizer)
+        self.Add(ebuttonspanel, pos = (base_line + 2, 0), span = (1, 5), flag = wx.EXPAND)
+
+    esettingspanel = root.newPanel(parentpanel)
+    esettingssizer = wx.BoxSizer(wx.HORIZONTAL)
+    root.edist = wx.SpinCtrl(esettingspanel,-1, "5", min = 0, max = 1000, size = (70,-1))
     root.edist.SetBackgroundColour((225, 200, 200))
     root.edist.SetForegroundColour("black")
-    self.Add(root.edist, pos = (base_line + 3, 0), span = (1, 1), flag = wx.EXPAND | wx.RIGHT, border = 5)
-    self.Add(wx.StaticText(parentpanel, -1, _("mm")), pos = (base_line + 3, 1), span = (1, 1))
+    esettingssizer.Add(root.edist, flag = wx.ALIGN_CENTER | wx.RIGHT, border = 5)
+    esettingssizer.Add(wx.StaticText(esettingspanel, -1, _("mm @")), flag = wx.ALIGN_CENTER | wx.RIGHT, border = 5)
     root.edist.SetToolTip(wx.ToolTip("Amount to Extrude or Retract (mm)"))
-    root.efeedc = wx.SpinCtrl(parentpanel,-1, str(root.settings.e_feedrate), min = 0, max = 50000, size = (70,-1))
+    root.efeedc = wx.SpinCtrl(esettingspanel,-1, str(root.settings.e_feedrate), min = 0, max = 50000, size = (70,-1))
     root.efeedc.SetToolTip(wx.ToolTip("Extrude / Retract speed (mm/min)"))
     root.efeedc.SetBackgroundColour((225, 200, 200))
     root.efeedc.SetForegroundColour("black")
     root.efeedc.Bind(wx.EVT_SPINCTRL, root.setfeeds)
     root.efeedc.Bind(wx.EVT_TEXT, root.setfeeds)
-    self.Add(root.efeedc, pos = (base_line + 3, 2), span = (1, 2), flag = wx.EXPAND | wx.RIGHT, border = 5)
-    self.Add(wx.StaticText(parentpanel, -1, _("mm/\nmin")), pos = (base_line + 3, 4), span = (2, 1))
+    esettingssizer.Add(root.efeedc, flag = wx.ALIGN_CENTER | wx.RIGHT, border = 5)
+    esettingssizer.Add(wx.StaticText(esettingspanel, -1, _("mm/\nmin")), flag = wx.ALIGN_CENTER)
+    esettingspanel.SetSizer(esettingssizer)
+    self.Add(esettingspanel, pos = (base_line + 3, 0), span = (1, 5))
 
     gauges_base_line = base_line + 8 if standalone_mode else base_line + 5
     if root.display_gauges:
@@ -187,6 +206,12 @@ def add_extra_controls(self, root, parentpanel, extra_buttons = None):
         for i in extra_buttons:
             btn = extra_buttons[i]
             self.Add(btn, pos = pos_mapping[i.pos], span = span_mapping[i.pos], flag = wx.EXPAND)
+    else:
+        for i in root.cpbuttons:
+            if not i.pos or i.pos[0] != 4:
+                continue
+            btn = make_custom_button(root, ebuttonspanel, i)
+            ebuttonssizer.Add(btn, 1, flag = wx.EXPAND)
 
 class LeftPane(wx.GridBagSizer):
 
@@ -199,13 +224,11 @@ class LeftPane(wx.GridBagSizer):
         self.Add(self.xyzsizer, pos = (1, 0), span = (1, 6), flag = wx.ALIGN_CENTER)
        
         self.extra_buttons = {}
+        ebuttons = []
         for i in root.cpbuttons:
-            btn = make_button(parentpanel, i.label, root.procbutton, i.tooltip)
-            btn.SetBackgroundColour(i.background)
-            btn.SetForegroundColour("black")
-            btn.properties = i
-            root.btndict[i.command] = btn
-            root.printerControls.append(btn)
+            if not standalone_mode and i.pos and i.pos[0] == 4:
+                continue
+            btn = make_custom_button(root, parentpanel, i)
             if i.pos == None:
                 if i.span == 0:
                     llts.Add(btn)
@@ -350,13 +373,13 @@ def MainToolbar(root, parentpanel = None, use_wrapsizer = False):
 
     root.resetbtn = make_autosize_button(parentpanel, _("Reset"), root.reset, _("Reset the printer"), self)
     root.loadbtn = make_autosize_button(parentpanel, _("Load file"), root.loadfile, _("Load a 3D model file"), self)
-    root.platebtn = make_autosize_button(parentpanel, _("Compose"), root.plate, _("Simple Plater System"), self)
     root.sdbtn = make_autosize_button(parentpanel, _("SD"), root.sdmenu, _("SD Card Printing"), self)
     root.printerControls.append(root.sdbtn)
     root.printbtn = make_sized_button(parentpanel, _("Print"), root.printfile, _("Start Printing Loaded File"), self)
     root.printbtn.Disable()
     root.pausebtn = make_sized_button(parentpanel, _("Pause"), root.pause, _("Pause Current Print"), self)
-    root.recoverbtn = make_sized_button(parentpanel, _("Recover"), root.recover, _("Recover previous Print"), self)
+    root.offbtn = make_sized_button(parentpanel, _("Off"), root.off, _("Turn printer off"), self)
+    root.printerControls.append(root.offbtn)
     return self
 
 class MainWindow(wx.Frame):

printrun/stlview.py

@@ -27,6 +27,7 @@ import pyglet
 pyglet.options['debug_gl'] = True
 
 from pyglet.gl import *
+from pyglet import gl
 
 from .gl.panel import wxGLPanel
 from .gl.trackball import trackball, mulquat, build_rotmatrix

pronsole.py

@@ -911,6 +911,9 @@ class pronsole(cmd.Cmd):
     def help_pause(self):
         self.log(_("Pauses a running print"))
 
+    def pause(self, event):
+        return self.do_pause(None)
+
     def do_resume(self, l):
         if not self.paused:
             self.logError(_("Not paused, unable to resume. Start a print first."))
@@ -1417,6 +1420,23 @@ class pronsole(cmd.Cmd):
         self.log(_("home e - set extruder position to zero (Using G92)"))
         self.log(_("home xyze - homes all axes and zeroes the extruder (Using G28 and G92)"))
 
+    def do_off(self, l):
+        self.off()
+
+    def off(self):
+        if self.p.online:
+            if self.p.printing: self.pause(None)
+            self.onecmd("M84; motors off")
+            self.onecmd("M104 S0; extruder off")
+            self.onecmd("M140 S0; heatbed off")
+            self.onecmd("M107; fan off")
+            self.onecmd("M81; power supply off")
+        else:
+            self.logError(_("Printer is not online. Unable to turn it off."))
+
+    def help_off(self):
+        self.log(_("Turns off everything on the printer"))
+
     def add_cmdline_arguments(self, parser):
         parser.add_argument('-c','--conf','--config', help = _("load this file on startup instead of .pronsolerc ; you may chain config files, if so settings auto-save will use the last specified file"), action = "append", default = [])
         parser.add_argument('-e','--execute', help = _("executes command after configuration/.pronsolerc is loaded ; macros/settings from these commands are not autosaved"), action = "append", default = [])

pronterface.py

@@ -579,12 +579,22 @@ class PronterWindow(MainWindow, pronsole.pronsole):
         # File menu
         m = wx.Menu()
         self.Bind(wx.EVT_MENU, self.loadfile, m.Append(-1, _("&Open..."), _(" Opens file")))
-        self.Bind(wx.EVT_MENU, self.do_editgcode, m.Append(-1, _("&Edit..."), _(" Edit open file")))
         self.Bind(wx.EVT_MENU, self.clearOutput, m.Append(-1, _("Clear console"), _(" Clear output console")))
-        self.Bind(wx.EVT_MENU, self.exclude, m.Append(-1, _("Excluder"), _(" Exclude parts of the bed from being printed")))
-        self.Bind(wx.EVT_MENU, self.project, m.Append(-1, _("Projector"), _(" Project slices")))
         self.Bind(wx.EVT_MENU, self.OnExit, m.Append(wx.ID_EXIT, _("E&xit"), _(" Closes the Window")))
         self.menustrip.Append(m, _("&File"))
+        
+        m = wx.Menu()
+        self.Bind(wx.EVT_MENU, self.do_editgcode, m.Append(-1, _("&Edit..."), _(" Edit open file")))
+        self.Bind(wx.EVT_MENU, self.plate, m.Append(-1, _("Plater"), _(" Compose 3D models into a single plate")))
+        self.Bind(wx.EVT_MENU, self.exclude, m.Append(-1, _("Excluder"), _(" Exclude parts of the bed from being printed")))
+        self.Bind(wx.EVT_MENU, self.project, m.Append(-1, _("Projector"), _(" Project slices")))
+        self.menustrip.Append(m, _("&Tools"))
+        
+        m = wx.Menu()
+        self.recoverbtn = m.Append(-1, _("Recover"), _(" Recover previous print after a disconnect (homes X, Y, restores Z and E status)"))
+        self.recoverbtn.Disable = lambda *a: self.recoverbtn.Enable(False)
+        self.Bind(wx.EVT_MENU, self.recover, self.recoverbtn)
+        self.menustrip.Append(m, _("&Advanced"))
 
         # Settings menu
         m = wx.Menu()
@@ -1127,9 +1137,9 @@ class PronterWindow(MainWindow, pronsole.pronsole):
         self.xyb.repeatLast()
 
     def parseusercmd(self, line):
-        if line.startswith("M114"):
+        if line.upper().startswith("M114"):
             self.userm114 += 1
-        elif line.startswith("M105"):
+        elif line.upper().startswith("M105"):
             self.userm105 += 1
 
     def procbutton(self, e):
@@ -1307,10 +1317,19 @@ class PronterWindow(MainWindow, pronsole.pronsole):
                     self.p.send_now("M27")
                 self.p.send_now("M105")
             cur_time = time.time()
-            while time.time() < cur_time + self.monitor_interval:
+            wait_time = 0
+            while time.time() < cur_time + self.monitor_interval - 0.25:
                 if not self.statuscheck:
                     break
                 time.sleep(0.25)
+                # Safeguard: if system time changes and goes back in the past,
+                # we could get stuck almost forever
+                wait_time += 0.25
+                if wait_time > self.monitor_interval - 0.25:
+                    break
+            # Always sleep at least a bit, if something goes wrong with the
+            # system time we'll avoid freezing the whole app this way
+            time.sleep(0.25)
             try:
                 while not self.sentlines.empty():
                     gc = self.sentlines.get_nowait()