Finished adding analogue and pwm

Author: Thomas Preston

CHANGELOG

@@ -5,7 +5,7 @@ v0.7.0
 ------
 - Fixed bytes error in serial_channel_device -- and/or/bulk commands
   work again.
-- Added support for analogue inputs, PWM and added music helper methods.
+- Added support for analogue inputs and PWM.
 
 v0.6.1
 ------

codebug_tether/__init__.py

@@ -2,4 +2,7 @@
                                  IO_DIGITAL_OUTPUT,
                                  IO_DIGITAL_INPUT,
                                  IO_ANALOGUE_INPUT,
-                                 IO_PWM_OUTPUT)
+                                 IO_PWM_OUTPUT,
+                                 T2_PS_1_1,
+                                 T2_PS_1_4,
+                                 T2_PS_1_16)

codebug_tether/core.py

@@ -65,6 +65,10 @@
 
 UART_DEFAULT_BAUD = 9600
 
+T2_PS_1_1 = 0
+T2_PS_1_4 = 1
+T2_PS_1_16 = 2
+
 
 class InvalidBaud(Exception):
     pass
@@ -184,16 +188,30 @@ def pwm_on(self, t2_prescale, full_period, on_period):
         """
         # full period
         self.set(CHANNEL_INDEX_PWM_CONF_0, full_period)
-        self.set(CHANNEL_INDEX_PWM_CONF_1, on_period | 0xff)
+        self.set(CHANNEL_INDEX_PWM_CONF_1, on_period & 0xff)
         go_busy = 1
         top_two_bit_on_period = (on_period >> 8) & 0b11
         conf = go_busy << 4 | t2_prescale << 2 | top_two_bit_on_period
         self.set(CHANNEL_INDEX_PWM_CONF_2, conf)
 
     def pwm_freq(self, frequency):
-        """Turns on the PWM generator with the given frequency."""
+        """Turns on the PWM generator with the given frequency. For example:
+
+            >>> codebug = CodeBug()
+            >>> codebug.set_leg_io(0, IO_PWM_OUTPUT)
+            >>> codebug.pwm_freq(1046)
+            >>> time.sleep(2)
+            >>> codebug.pwm_off()
+
+        """
         # calculate pwm settings
-        # self.pwm_on(settings)
+        # 4 MHz / 16 = 250k ticks per second
+        full_period = int(250000 / frequency) - 1
+        # for 50% duty cycle: shift up by 2 then /(2 i.e. 50% duty cycle)
+        # on_period = (full_period << 2) / 2;
+        # this is quicker
+        on_period = full_period << 1
+        self.pwm_on(T2_PS_1_16, full_period, on_period)
         pass
 
     def pwm_off(self):

codebug_tether/version.py

@@ -1 +1 @@
-__version__ = '0.6.1'
+__version__ = '0.7.0'

docs/example.rst

@@ -107,6 +107,59 @@ You can also change the direction text is written in::
     >>> bottom_to_top_msg = StringSprite('Hello CodeBug!', direction='U')
 
 
+Analogue Input
+==============
+You can read analogue inputs from all 8 of CodeBug's I/O legs/extension
+pins::
+
+    >>> import codebug_tether
+    >>> from codebug_tether import (IO_DIGITAL_INPUT,
+    ...                             IO_ANALOGUE_INPUT,
+    ...                             IO_PWM_OUTPUT,
+    ...                             IO_DIGITAL_OUTPUT)
+    ...
+    >>> codebug = codebug_tether.CodeBug()
+    >>> codebug.set_leg_io(0, IO_ANALOGUE_INPUT)
+    >>> codebug.read_analogue(0)
+    128
+
+
+PWM Output
+==========
+You can drive one synchronised PWM (Pulse Width Modulation) signal out
+of the first three legs on CodeBug. That is, the same PWM signal will
+be driven out of legs configured as PWM output::
+
+    >>> import codebug_tether
+    >>> from codebug_tether import (IO_DIGITAL_INPUT,
+    ...                             IO_ANALOGUE_INPUT,
+    ...                             IO_PWM_OUTPUT,
+    ...                             IO_DIGITAL_OUTPUT,
+    ...                             T2_PS_1_1,
+    ...                             T2_PS_1_4,
+    ...                             T2_PS_1_16)
+
+    >>> codebug = codebug_tether.CodeBug()
+    >>> # configure legs 0 and 1 to be PWM output
+    >>> codebug.set_leg_io(0, IO_PWM_OUTPUT)
+    >>> codebug.set_leg_io(1, IO_PWM_OUTPUT)
+    >>> # shortcut method to specify a frequency (the note C == 1046 Hz)
+    >>> codebug.pwm_freq(1046)
+    >>> time.sleep(2)
+    >>> codebug.pwm_off()
+
+Or you can be more specific with the duty cycle and timing::
+
+    >>> # pwm on with 1:4 prescaler and 75% duty cycle @ ~977Hz
+    >>> # Timer 2 prescale: 4Mhz clock / 4 = 1MHz timer speed
+    >>> # full_period: 255 << 2 = 1024  (timer resets at this count; PWM = 1)
+    >>> # on_period: 765 (PWM goes to zero at this count; PWM = 0)
+    >>> # therefore duty cycle here is 75%
+    >>> codebug.pwm_on(T2_PS_1_4, 255, 765)
+    >>> time.sleep(2)
+    >>> codebug.pwm_off()
+
+
 Colour Tail
 ===========
 You can control Colour Tails (WS2812's) attached to CodeBug. By default,