Added plugin for supporting MCP3008 ADC for analog sensors

platypush/plugins/gpio/sensor/mcp3008/__init__.py

@@ -0,0 +1,88 @@
+import enum
+import logging
+import time
+
+import Adafruit_GPIO.SPI as SPI
+import Adafruit_MCP3008
+
+from platypush.plugins.gpio.sensor import GpioSensorPlugin
+from platypush.message.response import Response
+
+
+class MCP3008Mode(enum.Enum):
+    SOFTWARE = 'software'
+    HARDWARE = 'hardware'
+
+
+class GpioSensorMcp3008Plugin(GpioSensorPlugin):
+    """
+    Plugin to read analog sensor values from an MCP3008 chipset,
+    see https://learn.adafruit.com/raspberry-pi-analog-to-digital-converters/mcp3008
+    Requires adafruit-mcp3008 Python package
+    """
+
+    N_CHANNELS = 8
+
+    def __init__(self, CLK=None, MISO=None, MOSI=None, CS=None, spi_port=None,
+                 spi_device=None, channels=None, Vdd=3.3, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        if CLK and MISO and MOSI and CS:
+            self.CLK = CLK
+            self.MISO = MISO
+            self.MOSI = MOSI
+            self.CS = CS
+            self.mode = MCP3008Mode.SOFTWARE
+        elif spi_port and spi_device:
+            self.spi_port = spi_port
+            self.spi_device = spi_device
+            self.mode = MCP3008Mode.HARDWARE
+        else:
+            raise RuntimeError("At least one mode must be specified.\n" +
+                               "Software SPI: Specify CLK, MISO, MOSI and CS pins\n" +
+                               "Hardware SPI: Specify spi_port and spi_device\n")
+
+        self.Vdd = Vdd
+        self.channels = channels if channels else {}
+        self.mcp = None
+
+
+    def _get_mcp(self):
+        if self.mode == MCP3008Mode.SOFTWARE:
+            self.mcp = Adafruit_MCP3008.MCP3008(clk=self.CLK, cs=self.CS,
+                                           miso=self.MISO, mosi=self.MOSI)
+        elif self.mode == MCP3008Mode.HARDWARE:
+            self.mcp = Adafruit_MCP3008.MCP3008(spi=SPI.SpiDev(self.spi_port, self.spi_device))
+        else:
+            raise RuntimeError('Unsupported MCP3008 mode: {}'.format(self.mode))
+
+        return self.mcp
+
+
+    def _convert_to_voltage(self, value):
+        return (value * self.Vdd) / 1023.0 if value is not None else None
+
+
+    def get_measurement(self):
+        mcp = self._get_mcp()
+        values = {}
+
+        for i in range(self.N_CHANNELS):
+            value = self._convert_to_voltage(mcp.read_adc(i))
+
+            if self.channels:
+                if i in self.channels:
+                    channel = self.channels[i]
+                    if 'conv_function' in channel:
+                        x = value
+                        value = eval(channel['conv_function'])
+
+                    values[channel['name']] = value
+            else:
+                values[i] = value
+
+        return Response(output=values)
+
+
+# vim:sw=4:ts=4:et:
+

setup.py

@@ -80,6 +80,8 @@ setup(
         'Support for most of the HTTP poll backends': ['python-dateutil'],
         'Support for Last.FM scrobbler plugin': ['pylast'],
         'Support for custom hotword detection': ['snowboy'],
+        'Support for GPIO pins access': ['RPi.GPIO'],
+        'Support for MCP3008 analog-to-digital converter plugin': ['adafruit-mcp3008'],
         # 'Support for Flic buttons': ['git+ssh://git@github.com/50ButtonsEach/fliclib-linux-hci']
     },
 )