wasp: pinetime: Basic RTC support

Currently this supports time only (no date) and it based on the
RTCounter class which is customized for nRF ports. At present
the nRF port doesn't have proper machine.rtc support so we have
implemented within wasp instead.

wasp/boards/pinetime/manifest.py

@@ -3,6 +3,7 @@ freeze('../..',
         'boot.py',
         'demo.py',
         'drivers/battery.py',
+        'drivers/nrf_rtc.py',
         'drivers/signal.py',
         'drivers/st7789.py',
         'drivers/vibrator.py',

wasp/boards/pinetime/watch.py

@@ -1,9 +1,10 @@
 from machine import Pin
-from machine import RTCounter as RTC
+from machine import RTCounter
 #from machine import Signal
 from machine import SPI
 
 from drivers.battery import Battery
+from drivers.nrf_rtc import RTC
 from drivers.signal import Signal
 from drivers.st7789 import ST7789_SPI
 from drivers.vibrator import Vibrator
@@ -50,11 +51,12 @@ display = Display()
 backlight.set(1)
 
 # Start measuring time (and feeding the watchdog)
-rtc = RTC(1, mode=RTC.PERIODIC)
-rtc.start()
+rtc = RTC(RTCounter(1, mode=RTCounter.PERIODIC))
+rtc.counter.start()
 
 battery = Battery(
         Pin('BATTERY', Pin.IN),
         Signal(Pin('CHARGING', Pin.IN), invert=True),
         Signal(Pin('USB_PWR', Pin.IN), invert=True))
 vibrator = Vibrator(Pin('MOTOR', Pin.OUT, value=0), active_low=True)
+button = Pin('BUTTON', Pin.IN)

wasp/drivers/nrf_rtc.py

@@ -0,0 +1,58 @@
+""" Real Time Clock based on the nRF-family low power counter """
+
+#class Stim(object):
+#    def __init__(self):
+#        self(0)
+#
+#    def __call__(self, v):
+#        self.c = v
+#    
+#    def counter(self):
+#        return self.c
+
+class RTC(object):
+    """Real Time Clock based on the nRF-family low power counter.
+
+    TODO: Maintain hh:mm:ss as an array so we can report time
+          without memory allocation.
+    """
+
+    def __init__(self, counter):
+        self.counter = counter
+        self.uptime = 0
+        self.set_time((12, 0, 0))
+
+    def update(self):
+        newcount = self.counter.counter()
+        split = newcount - self.lastcount
+        if split == 0:
+            return False
+        if split < 0:
+            split += (1 << 24)
+        elapsed = split // 8
+        self.lastcount += elapsed * 8 
+        self.lastcount &= (1 << 24) - 1   
+
+        self.uptime += elapsed
+
+        self.ss += elapsed
+        if self.ss >= 60:
+            self.mm += self.ss // 60
+            self.ss %= 60
+
+            if self.mm >= 60:
+                self.hh += self.mm // 60
+                self.mm %= 60
+                self.hh %= 24
+
+        return True
+
+    def set_time(self, t):
+        self.lastcount = self.counter.counter()
+        self.hh = t[0]
+        self.mm = t[1]
+        self.ss = t[2]
+
+    def get_time(self):
+        self.update()
+        return (self.hh, self.mm, self.ss)