revert PR_9

adafruit_am2320.py

@@ -77,21 +77,6 @@ def _crc16(data):
     return crc
 
 
-class AM2320Exception(Exception):
-    """Base class for exceptions."""
-
-
-class AM2320DeviceNotFound(AM2320Exception, ValueError):
-    """Indicates that a device couldn't be found."""
-
-
-class AM2320ReadError(AM2320Exception, RuntimeError):
-    """indicates that valid data could not be read from the sensor.
-
-    This may be due to a regular I2C read failure, or due to a checksum
-    mismatch."""
-
-
 class AM2320:
     """A driver for the AM2320 temperature and humidity sensor.
 
@@ -109,7 +94,7 @@ class AM2320:
             except ValueError:
                 pass
             time.sleep(0.25)
-        raise AM2320DeviceNotFound("AM2320 not found")
+        raise ValueError("AM2320 not found")
 
     def _read_register(self, register, length):
         with self._i2c as i2c:
@@ -130,12 +115,12 @@ class AM2320:
             # print("$%02X => %s" % (register, [hex(i) for i in result]))
             # Check preamble indicates correct readings
             if result[0] != 0x3 or result[1] != length:
-                raise AM2320ReadError("I2C read failure")
+                raise RuntimeError("I2C read failure")
             # Check CRC on all but last 2 bytes
             crc1 = struct.unpack("<H", bytes(result[-2:]))[0]
             crc2 = _crc16(result[0:-2])
             if crc1 != crc2:
-                raise AM2320ReadError("CRC failure 0x%04X vs 0x%04X" % (crc1, crc2))
+                raise RuntimeError("CRC failure 0x%04X vs 0x%04X" % (crc1, crc2))
             return result[2:-2]
 
     @property

pi@gjnpi4desk.local

@@ -0,0 +1,138 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2018 Limor Fried
+#
+# 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.
+"""
+`adafruit_am2320`
+====================================================
+
+This is a CircuitPython driver for the AM2320 temperature and humidity sensor.
+
+* Author(s): Limor Fried
+
+Implementation Notes
+--------------------
+
+**Hardware:**
+
+* Adafruit `AM2320 Temperature & Humidity Sensor
+  <https://www.adafruit.com/product/3721>`_ (Product ID: 3721)
+
+**Software and Dependencies:**
+
+* Adafruit CircuitPython firmware for the ESP8622 and M0-based boards:
+    https://github.com/adafruit/circuitpython/releases
+* Adafruit's Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
+
+"""
+
+# imports
+try:
+    import struct
+except ImportError:
+    import ustruct as struct
+
+import time
+
+from adafruit_bus_device.i2c_device import I2CDevice
+from micropython import const
+
+__version__ = "0.0.0-auto.0"
+__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_am2320.git"
+
+
+AM2320_DEFAULT_ADDR = const(0x5C)
+AM2320_CMD_READREG = const(0x03)
+AM2320_REG_TEMP_H = const(0x02)
+AM2320_REG_HUM_H = const(0x00)
+
+
+def _crc16(data):
+    crc = 0xFFFF
+    for byte in data:
+        crc ^= byte
+        for _ in range(8):
+            if crc & 0x0001:
+                crc >>= 1
+                crc ^= 0xA001
+            else:
+                crc >>= 1
+    return crc
+
+
+class AM2320:
+    """A driver for the AM2320 temperature and humidity sensor.
+
+    :param i2c_bus: The `busio.I2C` object to use. This is the only required parameter.
+    :param int address: (optional) The I2C address of the device.
+
+    """
+
+    def __init__(self, i2c_bus, address=AM2320_DEFAULT_ADDR):
+        for _ in range(3):
+            # retry since we have to wake up the devices
+            try:
+                self._i2c = I2CDevice(i2c_bus, address)
+                return
+            except ValueError:
+                pass
+            time.sleep(0.25)
+        raise ValueError("AM2320 not found")
+
+    def _read_register(self, register, length):
+        with self._i2c as i2c:
+            # wake up sensor
+            try:
+                i2c.write(bytes([0x00]))
+            except OSError:
+                pass
+            time.sleep(0.01)  # wait 10 ms
+
+            # Send command to read register
+            cmd = [AM2320_CMD_READREG, register & 0xFF, length]
+            # print("cmd: %s" % [hex(i) for i in cmd])
+            i2c.write(bytes(cmd))
+            time.sleep(0.002)  # wait 2 ms for reply
+            result = bytearray(length + 4)  # 2 bytes pre, 2 bytes crc
+            i2c.readinto(result)
+            # print("$%02X => %s" % (register, [hex(i) for i in result]))
+            # Check preamble indicates correct readings
+            if result[0] != 0x3 or result[1] != length:
+                raise RuntimeError("I2C read failure")
+            # Check CRC on all but last 2 bytes
+            crc1 = struct.unpack("<H", bytes(result[-2:]))[0]
+            crc2 = _crc16(result[0:-2])
+            if crc1 != crc2:
+                raise RuntimeError("CRC failure 0x%04X vs 0x%04X" % (crc1, crc2))
+            return result[2:-2]
+
+    @property
+    def temperature(self):
+        """The measured temperature in celsius."""
+        temperature = struct.unpack(">H", self._read_register(AM2320_REG_TEMP_H, 2))[0]
+        if temperature >= 32768:
+            temperature = 32768 - temperature
+        return temperature / 10.0
+
+    @property
+    def relative_humidity(self):
+        """The measured relative humidity in percent."""
+        humidity = struct.unpack(">H", self._read_register(AM2320_REG_HUM_H, 2))[0]
+        return humidity / 10.0