X-Git-Url: https://git.ayoreis.com/Adafruit_Blinka-hackapet.git/blobdiff_plain/a3770186a94117be56a8d9a8038a2d540bd2884c..80a2f37a06c217e101373df892bf4a083c03012a:/src/adafruit_blinka/microcontroller/generic_linux/sysfs_analogin.py

diff --git a/src/adafruit_blinka/microcontroller/generic_linux/sysfs_analogin.py b/src/adafruit_blinka/microcontroller/generic_linux/sysfs_analogin.py
new file mode 100644
index 0000000..bf6988b
--- /dev/null
+++ b/src/adafruit_blinka/microcontroller/generic_linux/sysfs_analogin.py
@@ -0,0 +1,95 @@
+"""
+`analogio` - Analog input control
+=================================================
+Read the SysFS ADC using IIO (Industrial Input/Output) and return the value
+
+See `CircuitPython:analogio` in CircuitPython for more details.
+* Author(s): Melissa LeBlanc-Williams
+"""
+
+import os
+from adafruit_blinka import ContextManaged
+
+try:
+    from microcontroller.pin import analogIns
+except ImportError:
+    raise RuntimeError("No Analog Inputs defined for this board")
+
+
+class AnalogIn(ContextManaged):
+    """Analog Input Class"""
+
+    # Sysfs paths
+    _sysfs_path = "/sys/bus/iio/devices/"
+    _device_path = "iio:device{}"
+
+    # Channel paths
+    _channel_path = "in_voltage{}_raw"
+    _scale_path = "in_voltage_scale"
+
+    def __init__(self, adc_id):
+        """Instantiate an AnalogIn object and verify the sysfs IIO
+        corresponding to the specified channel and pin.
+
+        Args:
+            adc_id (int): Analog Input ID as defined in microcontroller.pin
+
+        Returns:
+            AnalogIn: AnalogIn object.
+
+        Raises:
+            TypeError: if `channel` or `pin` types are invalid.
+            ValueError: if AnalogIn channel does not exist.
+
+        """
+
+        self.id = adc_id
+        self._device = None
+        self._channel = None
+        self._open(adc_id)
+
+    def __enter__(self):
+        return self
+
+    def _open(self, adc_id):
+        self._device = None
+        for adcpair in analogIns:
+            if adcpair[0] == adc_id:
+                self._device = adcpair[1]
+                self._channel = adcpair[2]
+
+        if self._device is None:
+            raise RuntimeError("No AnalogIn device found for the given ID")
+
+        device_path = os.path.join(
+            self._sysfs_path, self._device_path.format(self._device)
+        )
+
+        if not os.path.isdir(device_path):
+            raise ValueError(
+                "AnalogIn device does not exist, check that the required modules are loaded."
+            )
+
+    @property
+    def value(self):
+        """Read the ADC and return the value as an integer"""
+        path = os.path.join(
+            self._sysfs_path,
+            self._device_path.format(self._device),
+            self._channel_path.format(self._channel),
+        )
+
+        with open(path, "r") as analog_in:
+            return int(analog_in.read().strip())
+
+    # pylint: disable=no-self-use
+    @value.setter
+    def value(self, value):
+        # emulate what CircuitPython does
+        raise AttributeError("'AnalogIn' object has no attribute 'value'")
+
+    # pylint: enable=no-self-use
+
+    def deinit(self):
+        self._device = None
+        self._channel = None