Stop using memoryviews and start using I2CDevice to manage transaction related state.

tannewt · tannewt · commit ec1afdff2eef · 2016-12-02T16:19:15.000-08:00
diff --git a/.gitignore b/.gitignore
@@ -3,3 +3,4 @@
 dist
 *.pyc
 _build/
+*.mpy
diff --git a/README.md b/README.md
@@ -5,9 +5,11 @@ SPI register based device. Data descriptors act like basic attributes from the
 outside which makes using them really easy.
 
 ## Creating a driver
-Creating a driver with the register library is really easy. First, import the register modules you need from the [available modules](adafruit_register/index.html):
+Creating a driver with the register library is really easy. First, import the
+register modules you need from the [available modules](adafruit_register/index.html):
 
     from adafruit_register import i2c_bit
+    from adafruit_bus_device import i2c_device
 
 Next, define where the bit is located in the device's memory map:
 
@@ -20,14 +22,13 @@ Next, define where the bit is located in the device's memory map:
         world = i2c_bit.RWBit(0x1, 0x0)
         """Bit to indicate if world is lit."""
 
-Lastly, we need to add two instance members `i2c` and `device_address` so that
-the register classes know how to talk to the device. Make sure their names are
-exact, otherwise the registers will not be able to find them. Also, make sure
-that the i2c device implements the `nativeio.I2C` interface.
+Lastly, we need to add an `i2c_device` member that manages sharing the I2C bus
+for us. Make sure the name is exact, otherwise the registers will not be able to
+find it. Also, make sure that the i2c device implements the `nativeio.I2C`
+interface.
 
         def __init__(self, i2c, device_address=0x0):
-            self.i2c = i2c
-            self.device_address = device_address
+            self.i2c_device = i2c_device.I2CDevice(i2c, device_address)
 
 Thats it! Now we have a class we can use to talk to those registers:
 
@@ -40,9 +41,14 @@ Thats it! Now we have a class we can use to talk to those registers:
         device.world = True
 
 ## Adding register types
-Adding a new register type is a little more complicated because you need to be careful and minimize the amount of memory the class will take. If you don't, then a driver with five registers of your type could take up five times more extra memory.
+Adding a new register type is a little more complicated because you need to be
+careful and minimize the amount of memory the class will take. If you don't,
+then a driver with five registers of your type could take up five times more
+extra memory.
 
-First, determine whether the new register class should go in an existing module or not. When in doubt choose a new module. The more finer grained the modules are, the fewer extra classes a driver needs to load in.
+First, determine whether the new register class should go in an existing module
+or not. When in doubt choose a new module. The more finer grained the modules
+are, the fewer extra classes a driver needs to load in.
 
 Here is the start of the `RWBit` class:
 
@@ -70,7 +76,7 @@ register classes will be shared.
 
 In `__init__` we only use two member variable because each costs 8 bytes of
 memory plus the memory for the value. And remember this gets multiplied by the
-number of registers of this type in a device! Thats why we pack both the
+number of registers of this type in a driver! Thats why we pack both the
 register address and data byte into one bytearray. We could use two byte arrays
 of size one but each MicroPython object is 16 bytes minimum due to the garbage
 collector. So, by sharing a byte array we keep it to the 16 byte minimum instead
@@ -85,24 +91,29 @@ Ok, onward. To make a [data descriptor](https://docs.python.org/3/howto/descript
 we must implement `__get__` and `__set__`.
 
     def __get__(self, obj, objtype=None):
-        obj.i2c.writeto(obj.device_address, self.buffer, end=1, stop=False)
-        obj.i2c.readfrom_into(obj.device_address, self.buffer, start=1)
+        with obj.i2c_device:
+            obj.i2c_device.writeto(self.buffer, end=1, stop=False)
+            obj.i2c_device.readfrom_into(self.buffer, start=1)
         return bool(self.buffer[1] & self.bit_mask)
 
     def __set__(self, obj, value):
-        obj.i2c.writeto(obj.device_address, self.buffer, end=1, stop=False)
-        obj.i2c.readfrom_into(obj.device_address, self.buffer, start=1)
-        if value:
-            self.buffer[1] |= self.bit_mask
-        else:
-            self.buffer[1] &= ~self.bit_mask
-        obj.i2c.writeto(obj.device_address, self.buffer)
+        with obj.i2c_device:
+            obj.i2c_device.writeto(self.buffer, end=1, stop=False)
+            obj.i2c_device.readfrom_into(self.buffer, start=1)
+            if value:
+                self.buffer[1] |= self.bit_mask
+            else:
+                self.buffer[1] &= ~self.bit_mask
+            obj.i2c_device.writeto(self.buffer)
 
 As you can see, we have two places to get state from. First, `self` stores the
 register class members which locate the register within the device memory map.
-Second, `obj` is the device class that uses the register class which must by
-definition provide a `nativeio.I2C` compatible object as ``i2c`` and the 7-bit
-device address as ``device_address``.
+Second, `obj` is the driver class that uses the register class which must by
+definition provide a `adafruit_bus_device.I2CDevice` compatible object as
+``i2c_device``. This object does two thing for us:
+
+  1. Waits for the bus to free, locks it as we use it and frees it after.
+  2. Saves the device address and other settings so we don't have to.
 
 Note that we take heavy advantage of the ``start`` and ``end`` parameters to the
 i2c functions to slice the buffer without actually allocating anything extra.
diff --git a/adafruit_register/i2c_bcd_datetime.py b/adafruit_register/i2c_bcd_datetime.py
@@ -1,3 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
 try:
     import ucollections as collections
 except:
@@ -55,32 +77,32 @@ class BCDDateTimeRegister:
     def __init__(self, register_address):
         self.buffer = bytearray(8)
         self.buffer[0] = register_address
-        self.register_address = memoryview(self.buffer)[:1]
-        self.datetime = memoryview(self.buffer)[1:]
 
     def __get__(self, obj, objtype=None):
         # Read and return the date and time.
-        obj.i2c.writeto(obj.device_address, self.register_address, stop=False)
-        obj.i2c.readfrom_into(obj.device_address, self.datetime)
+        with obj.i2c_device:
+            obj.i2c_device.writeto(self.buffer, end=1, stop=False)
+            obj.i2c_device.readfrom_into(self.buffer, start=1)
         return datetime_tuple(
-            year=_bcd2bin(self.datetime[6]) + 2000,
-            month=_bcd2bin(self.datetime[5]),
-            day=_bcd2bin(self.datetime[4]),
-            weekday=_bcd2bin(self.datetime[3]),
-            hour=_bcd2bin(self.datetime[2]),
-            minute=_bcd2bin(self.datetime[1]),
-            second=_bcd2bin(self.datetime[0]),
+            year=_bcd2bin(self.buffer[7]) + 2000,
+            month=_bcd2bin(self.buffer[6]),
+            day=_bcd2bin(self.buffer[5]),
+            weekday=_bcd2bin(self.buffer[4]),
+            hour=_bcd2bin(self.buffer[3]),
+            minute=_bcd2bin(self.buffer[2]),
+            second=_bcd2bin(self.buffer[1]),
         )
 
     def __set__(self, obj, value):
-        self.datetime[0] = _bin2bcd(value.second)   # format conversions
-        self.datetime[1] = _bin2bcd(value.minute)
-        self.datetime[2] = _bin2bcd(value.hour)
-        self.datetime[3] = _bin2bcd(value.weekday)
-        self.datetime[4] = _bin2bcd(value.day)
-        self.datetime[5] = _bin2bcd(value.month)
-        self.datetime[6] = _bin2bcd(value.year - 2000)
-        obj.i2c.writeto(obj.device_address, self.buffer)
+        self.buffer[1] = _bin2bcd(value.second)   # format conversions
+        self.buffer[2] = _bin2bcd(value.minute)
+        self.buffer[3] = _bin2bcd(value.hour)
+        self.buffer[4] = _bin2bcd(value.weekday)
+        self.buffer[5] = _bin2bcd(value.day)
+        self.buffer[6] = _bin2bcd(value.month)
+        self.buffer[7] = _bin2bcd(value.year - 2000)
+        with obj.i2c_device:
+            obj.i2c_device.writeto(self.buffer)
 
 class BCDAlarmTimeRegister:
     """
@@ -95,25 +117,25 @@ class BCDAlarmTimeRegister:
     def __init__(self, register_address):
         self.buffer = bytearray(5)
         self.buffer[0] = register_address
-        self.register_address = memoryview(self.buffer)[:1]
-        self.alarm_time = memoryview(self.buffer)[1:]
 
     def __get__(self, obj, objtype=None):
         # Read the alarm register.
-        obj.i2c.writeto(obj.device_address, self.register_address, stop=False)
-        obj.i2c.readfrom_into(obj.device_address, self.alarm_time)
-        if not self.alarm_time[0] & 0x80:
+        with obj.i2c_device:
+            obj.i2c_device.writeto(self.buffer, end=1, stop=False)
+            obj.i2c_device.readfrom_into(self.buffer, start=1)
+        if not self.buffer[1] & 0x80:
             return None
         return datetime_tuple(
-            weekday=_bcd2bin(self.alarm_time[3] & 0x7f),
-            day=_bcd2bin(self.alarm_time[2] & 0x7f),
-            hour=_bcd2bin(self.alarm_time[1] & 0x7f),
-            minute=_bcd2bin(self.alarm_time[0] & 0x7f),
+            weekday=_bcd2bin(self.buffer[4] & 0x7f),
+            day=_bcd2bin(self.buffer[3] & 0x7f),
+            hour=_bcd2bin(self.buffer[2] & 0x7f),
+            minute=_bcd2bin(self.buffer[1] & 0x7f),
         )
 
     def __set__(self, obj, value):
-        self.alarm_time[1] = (_bin2bcd(value.minute) if value.minute is not None else 0x80)
-        self.alarm_time[2] = (_bin2bcd(value.hour) if value.hour is not None else 0x80)
-        self.alarm_time[3] = (_bin2bcd(value.day) if value.day is not None else 0x80)
-        self.alarm_time[4] = (_bin2bcd(value.weekday) | 0b01000000 if value.weekday is not None else 0x80)
-        obj.i2c.writeto(obj.device_address, self.buffer)
+        self.buffer[1] = (_bin2bcd(value.minute) if value.minute is not None else 0x80)
+        self.buffer[2] = (_bin2bcd(value.hour) if value.hour is not None else 0x80)
+        self.buffer[3] = (_bin2bcd(value.day) if value.day is not None else 0x80)
+        self.buffer[4] = (_bin2bcd(value.weekday) | 0b01000000 if value.weekday is not None else 0x80)
+        with obj.i2c_device:
+            obj.i2c_device.writeto(self.buffer)
diff --git a/adafruit_register/i2c_bit.py b/adafruit_register/i2c_bit.py
@@ -1,3 +1,25 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
 class RWBit:
     """
     Single bit register that is readable and writeable.
@@ -13,18 +35,20 @@ def __init__(self, register_address, bit):
         self.buffer[0] = register_address
 
     def __get__(self, obj, objtype=None):
-        obj.i2c.writeto(obj.device_address, self.buffer, end=1, stop=False)
-        obj.i2c.readfrom_into(obj.device_address, self.buffer, start=1)
+        with obj.i2c_device:
+            obj.i2c_device.writeto(self.buffer, end=1, stop=False)
+            obj.i2c_device.readfrom_into(self.buffer, start=1)
         return bool(self.buffer[1] & self.bit_mask)
 
     def __set__(self, obj, value):
-        obj.i2c.writeto(obj.device_address, self.buffer, end=1, stop=False)
-        obj.i2c.readfrom_into(obj.device_address, self.buffer, start=1)
-        if value:
-            self.buffer[1] |= self.bit_mask
-        else:
-            self.buffer[1] &= ~self.bit_mask
-        obj.i2c.writeto(obj.device_address, self.buffer)
+        with obj.i2c_device:
+            obj.i2c.writeto(self.buffer, end=1, stop=False)
+            obj.i2c.readfrom_into(self.buffer, start=1)
+            if value:
+                self.buffer[1] |= self.bit_mask
+            else:
+                self.buffer[1] &= ~self.bit_mask
+            obj.i2c_device.writeto(self.buffer)
 
 class ROBit(RWBit):
     """Single bit register that is read only. Subclass of `RWBit`.

-Original file line number
+Diff line change
 dist
 *.pyc
 _build/
 +*.mpy