revised per tannewt's review comments

Author: brentru

simpleio.py

@@ -31,9 +31,114 @@
 """
 
 import digitalio
+import pulseio
 import math
+import time
+import audioio
+import array
+import math
+
 from neopixel_write import neopixel_write
 
+
+def tone(pin, frequency, duration=0, tone_analog = False):
+    """
+    Generates a square wave of the specified frequency (50% duty cycle)
+    on a pin
+
+    :param pin: the pin on which to generate the tone
+    :param frequency: frequency of tone in Hz
+    :param duration: duration of tone in millis (optional)
+    :param tone_analog: uses analog pins instead of digital
+    """
+    if(tone_analog == False):
+        pwm = pulseio.PWMOut(pin, frequency = frequency, variable_frequency = False)
+        print(pwm.duty_cycle)
+        for i in range(0, duration):
+            pwm.duty_cycle = 2 ** 15
+            print(pwm.duty_cycle)
+            time.sleep(0.001)
+        pwm.deinit()
+    else:
+        length = 5000 // frequency
+        square_wave = array.array("H", [0] * length)
+        for i in range(length):
+            if(i%2 == 0):
+                square_wave.append((2 ** 16) - 1)
+            else:
+                square_wave.append(0x00)
+        sound = audioio.AudioOut(pin, square_wave)
+        sound.play(loop=True)
+        time.sleep(duration)
+        sound.stop()
+        sound.deinit()
+
+def shiftIn(dataPin, clock, msb_first=True):
+    """
+    Shifts in a byte of data one bit at a time. Starts from either the LSB or
+    MSB.
+
+    :param dataPin: pin on which to input each bit
+    :param clock: toggles to signal dataPin reads
+    :param msb_first: order to shift bits (least significant or most significant bit first)
+    :return: returns the value read
+    :rtype: int
+    """
+
+    value = 0
+    i = 0
+
+    for i in range(0, 8):
+        clock.value = True
+        if msb_first == False:
+            value |= ((dataPin.value) << i)
+            print(value)
+        else:
+            value |= ((dataPin.value) << (7-i))
+            print(value)
+        clock.value = False
+        i+=1
+    return value
+
+def shiftOut(dataPin, clock, value, msb_first=True):
+    """
+    Shifts out a byte of data one bit at a time. Data gets written to a data
+    pin. Then, the clock pulses hi then low
+
+    :param dataPin: value bits get output on this pin
+    :param clock: toggled once the data pin is set
+    :param msb_first: order to shift bits (least significant or most significant bit first)
+    :param value: byte to be shifted
+
+    Example for Metro Express:
+
+    .. code-block:: python
+
+        import digitalio
+        import simpleio
+        from board import *
+        clock = digitalio.DigitalInOut(D12)
+        dataPin = digitalio.DigitalInOut(D11)
+        clock.direction = digitalio.Direction.OUTPUT
+        dataPin.direction = digitalio.Direction.OUTPUT
+
+        while True:
+            valueSend = 500
+            shiftOut(dataPin, clock, 'LSBFIRST', (valueSend>>8))
+            shiftOut(dataPin, clock, 'LSBFIRST', valueSend)
+            shiftOut(dataPin, clock, 'MSBFIRST', (valueSend>>8))
+            shiftOut(dataPin, clock, 'MSBFIRST', valueSend)
+    """
+    value = value&0xFF
+    for i in range(0, 8):
+        if msb_first == False:
+            tmpval = bool((value & (1 << i)))
+            dataPin.value = tmpval
+        else:
+            tmpval = bool(value & (1 << (7-i)))
+            dataPin.value = tmpval
+        print (tmpval)
+
 class DigitalOut:
     """
     Simple digital output that is valid until soft reset.