lowpower: README and rtc_time.py refelect change to uasyncio.version

Author: peterhinch

lowpower/README.md

@@ -113,7 +113,7 @@ following:
 
 ```python
 try:
-    if asyncio.version != 'fast_io':
+    if asyncio.version[0] != 'fast_io':
         raise AttributeError
 except AttributeError:
     raise OSError('This requires fast_io fork of uasyncio.')
@@ -161,7 +161,7 @@ Applications can detect which timebase is in use by issuing:
 
 ```python
 try:
-    if asyncio.version != 'fast_io':
+    if asyncio.version[0] != 'fast_io':
         raise AttributeError
 except AttributeError:
     raise OSError('This requires fast_io fork of uasyncio.')
@@ -272,7 +272,7 @@ hardware and code. The only *required* change to application code is to add
 
 ```python
 try:
-    if asyncio.version != 'fast_io':
+    if asyncio.version[0] != 'fast_io':
         raise AttributeError
 except AttributeError:
     raise OSError('This requires fast_io fork of uasyncio.')

lowpower/rtc_time.py

@@ -23,7 +23,12 @@
     if mode is None:  # USB is disabled
         use_utime = False  # use RTC timebase
     elif 'VCP' in mode:  # User has enabled VCP in boot.py
-        if pyb.Pin.board.USB_VBUS.value() == 1:  # USB physically connected
+        usb_conn = pyb.Pin.board.USB_VBUS.value()  # USB physically connected to pyb V1.x
+        if not usb_conn:
+            usb_conn = hasattr(pyb.Pin.board, 'USB_HS_DP') and pyb.Pin.board.USB_HS_DP.value()
+        if not usb_conn:
+            usb_conn = hasattr(pyb.Pin.board, 'USB_DP') and pyb.Pin.board.USB_DP.value()
+        if usb_conn:
             print('USB connection: rtc_time disabled.')
         else:
             pyb.usb_mode(None)  # Save power