Remove busy wait, make sleep amount tune-able, fix initialization bug

Author: Tomáš Jozífek

RPLCD/gpio.py

@@ -46,7 +46,8 @@ def __init__(self, numbering_mode=None, pin_rs=None, pin_rw=None, pin_e=None, pi
                        cols=20, rows=4, dotsize=8,
                        charmap='A02',
                        auto_linebreaks=True,
-                       compat_mode=False):
+                       compat_mode=False,
+                       compat_mode_wait_time=0.001):
         """
         Character LCD controller.
 
@@ -94,6 +95,9 @@ def __init__(self, numbering_mode=None, pin_rs=None, pin_rw=None, pin_e=None, pi
         :param compat_mode: Whether to run additional checks to support older LCDs
             that may not run at the reference clock (or keep up with it).
         :type compat_mode: bool
+        :param compat_mode_wait_time: Minimum time to pass between sends.
+            if zero, turns off compat_mode  Default: ``0.001`` seconds.
+        :type compat_mode_wait_time: float
 
         """
 
@@ -130,7 +134,8 @@ def __init__(self, numbering_mode=None, pin_rs=None, pin_rw=None, pin_e=None, pi
         super(CharLCD, self).__init__(cols, rows, dotsize,
                                       charmap=charmap,
                                       auto_linebreaks=auto_linebreaks,
-                                      compat_mode=compat_mode)
+                                      compat_mode=compat_mode,
+                                      compat_mode_wait_time=compat_mode_wait_time)
 
         # Set backlight status
         if pin_backlight is not None:

RPLCD/lcd.py

@@ -32,9 +32,7 @@
     from time import clock as now
 else:
     from time import perf_counter as now
-
-# Duration to rate-limit calls to _send
-COMPAT_MODE_WAIT_TIME = 0.001
+from time import sleep
 
 LCDConfig = namedtuple('LCDConfig', 'rows cols dotsize')
 
@@ -45,7 +43,8 @@ class BaseCharLCD(object):
 
     # Init, setup, teardown
 
-    def __init__(self, cols=20, rows=4, dotsize=8, charmap='A02', auto_linebreaks=True, compat_mode=False):
+    def __init__(self, cols=20, rows=4, dotsize=8, charmap='A02', auto_linebreaks=True, compat_mode=False,
+                 compat_mode_wait_time=0.001):
         """
         Character LCD controller. Base class only, you should use a subclass.
 
@@ -63,10 +62,22 @@ def __init__(self, cols=20, rows=4, dotsize=8, charmap='A02', auto_linebreaks=Tr
             auto_linebreaks:
                 Whether or not to automatically insert line breaks.
                 Default: True.
-
+            compat_mode:
+                Whether to run additional checks to support older LCDs
+                that may not run at the reference clock (or keep up with it).
+                Default: False
+            compat_mode_wait_time: Minimum time to pass between sends.
+                if zero, turns off compat_mode
+                Default: ``0.001`` seconds.
         """
         assert dotsize in [8, 10], 'The ``dotsize`` argument should be either 8 or 10.'
 
+        # Configure compatibility mode
+        self.compat_mode = compat_mode and compat_mode_wait_time > 0
+        self.compat_mode_wait_time = compat_mode_wait_time
+        if compat_mode:
+            self.last_send_event = now()
+
         # Initialize codec
         if charmap == 'A00':
             self.codec = codecs.A00Codec()
@@ -146,11 +157,6 @@ def __init__(self, cols=20, rows=4, dotsize=8, charmap='A02', auto_linebreaks=Tr
         self.command(c.LCD_ENTRYMODESET | self._text_align_mode | self._display_shift_mode)
         c.usleep(50)
 
-        # Configure compatibility mode
-        self.compat_mode = compat_mode
-        if compat_mode:
-            self.last_send_event = now()
-
     def close(self, clear=False):
         if clear:
             self.clear()
@@ -255,9 +261,10 @@ def _set_cursor_mode(self, value):
 
     def _wait(self):
         """Rate limit the number of send events."""
-        end = self.last_send_event + COMPAT_MODE_WAIT_TIME
-        while now() < end:
-            pass
+        end = self.last_send_event + self.compat_mode_wait_time
+        sleep_duration = end - now()
+        if sleep_duration > 0:
+            sleep(sleep_duration)
 
     # High level commands
 

RPLCD/pigpio.py

@@ -58,7 +58,8 @@ def __init__(self, pi,
                        cols=20, rows=4, dotsize=8,
                        charmap='A02',
                        auto_linebreaks=True,
-                       compat_mode=False):
+                       compat_mode=False,
+                       compat_mode_wait_time=0.001):
         """
         Character LCD controller.
 
@@ -124,6 +125,9 @@ def __init__(self, pi,
         :param auto_linebreaks: Whether or not to automatically insert line
             breaks. Default: ``True``.
         :type auto_linebreaks: bool
+        :param compat_mode_wait_time: Minimum time to pass between sends.
+            if zero, turns off compat_mode  Default: ``0.001`` seconds.
+        :type compat_mode_wait_time: float
 
         """
 
@@ -158,7 +162,8 @@ def __init__(self, pi,
         super(CharLCD, self).__init__(cols, rows, dotsize,
                                       charmap=charmap,
                                       auto_linebreaks=auto_linebreaks,
-                                      compat_mode=compat_mode)
+                                      compat_mode=compat_mode,
+                                      compat_mode_wait_time=compat_mode_wait_time)
 
         # Set backlight status
         if pin_backlight is not None: