DS3231 setting RTC accuracy improved

DS3231/ds3231_pb.py

@@ -21,7 +21,7 @@ def now():  # Return the current time from the RTC in secs and millisecs from ye
 # Driver for DS3231 accurate RTC module (+- 1 min/yr) needs adapting for Pyboard
 # source https://github.com/scudderfish/uDS3231
 def bcd2dec(bcd):
-    return (((bcd & 0b11110000)>>4)*10 + (bcd & 0b00001111))
+    return (((bcd & 0xf0) >> 4) * 10 + (bcd & 0x0f))
 
 def dec2bcd(dec):
     t = dec // 10
@@ -42,7 +42,10 @@ class DS3231:
             raise DS3231Exception("DS3231 not found on I2C bus at %d" % DS3231_I2C_ADDR)
 
     def get_time(self, set_rtc = False):
-        data = self.ds3231.mem_read(7, DS3231_I2C_ADDR, 0)
+        if set_rtc:
+            data = self.await_transition() # For accuracy set RTC immediately after a seconds transition
+        else:
+            data = self.ds3231.mem_read(7, DS3231_I2C_ADDR, 0) # don't wait
         ss = bcd2dec(data[0])
         mm = bcd2dec(data[1])
         if data[2] & 0x40:
@@ -84,7 +87,8 @@ class DS3231:
         data = self.ds3231.mem_read(7, DS3231_I2C_ADDR, 0)
         ss = data[0]
         while ss == data[0]:
-            data = self.ds3231.mem_read(7, DS3231_I2C_ADDR, 0)      # Aawait a seconds transition
+            data = self.ds3231.mem_read(7, DS3231_I2C_ADDR, 0)      # Await a seconds transition
+        return data
 
 # Get calibration factor for Pyboard RTC. Note that the DS3231 doesn't have millisecond resolution so we
 # wait for a seconds transition to emulate it.