deepsleep: Improved deepsleep library reliability.

Due to timing, sometimes the pulses are going to be missed.

Author: Daniel Campora

deepsleep/deepsleep.py

@@ -39,7 +39,7 @@ def _send(self, data):
         self.uart.write(bytes(data))
 
     def _start(self):
-        self.uart.sendbreak(11)
+        self.uart.sendbreak(20)
         self._send([0x55])
 
     def _magic(self, address, and_val, or_val, xor_val, expected=None):
@@ -48,7 +48,8 @@ def _magic(self, address, and_val, or_val, xor_val, expected=None):
         if expected is None:
             return self.uart.read()
         else:
-            return self.uart.read(expected)
+            if expected > 0:
+                return self.uart.read(expected)
 
     def _add_to_pin_mask(self, mask, pin):
         if pin == 'P10' or pin == 'G17':
@@ -95,15 +96,17 @@ def calibrate(self):
             The idea is to measure the real life duration of periods marked with *
             and substract them. That will remove any errors common to both measurements
             The result is 7 ms as generated by the PIC LF clock.
-            It can be used to scale any future sleep value."""
+            It can be used to scale any future sleep value. """
 
         # setbits, but limit the number of received bytes to avoid confusion with pattern
-        self._magic(CTRL_0_ADDR, 0xFF, 1 << 2, 0, 7)
+        self._magic(CTRL_0_ADDR, 0xFF, 1 << 2, 0, 0)
         self.uart.deinit()
-        Pin(COMM_PIN, mode=Pin.IN)
-        pulses = pycom.pulses_get(COMM_PIN, 50000)
+        self._pulses = pycom.pulses_get(COMM_PIN, 50)
         self.uart = UART(1, baudrate=10000, pins=(COMM_PIN, ))
-        self.clk_cal_factor = (pulses[3][1] - pulses[1][1]) / EXP_RTC_PERIOD
+        try:
+            self.clk_cal_factor = (self._pulses[4][1] - self._pulses[1][1]) / EXP_RTC_PERIOD
+        except:
+            pass
         if self.clk_cal_factor > 1.25 or self.clk_cal_factor < 0.75:
             self.clk_cal_factor = 1