homecontrol-bh1750: initial commit

bh1750/__init__.py

@@ -0,0 +1,62 @@
+"""
+Micropython BH1750 ambient light sensor driver.
+from https://github.com/PinkInk/upylib
+"""
+
+from utime import sleep_ms
+
+
+class BH1750():
+    """Micropython BH1750 ambient light sensor driver."""
+
+    PWR_OFF = 0x00
+    PWR_ON = 0x01
+    RESET = 0x07
+
+    # modes
+    CONT_LOWRES = 0x13
+    CONT_HIRES_1 = 0x10
+    CONT_HIRES_2 = 0x11
+    ONCE_HIRES_1 = 0x20
+    ONCE_HIRES_2 = 0x21
+    ONCE_LOWRES = 0x23
+
+    # default addr=0x23 if addr pin floating or pulled to ground
+    # addr=0x5c if addr pin pulled high
+    def __init__(self, bus, addr=0x23):
+        self.bus = bus
+        self.addr = addr
+        self.off()
+        self.reset()
+
+    def off(self):
+        """Turn sensor off."""
+        self.set_mode(self.PWR_OFF)
+
+    def on(self):
+        """Turn sensor on."""
+        self.set_mode(self.PWR_ON)
+
+    def reset(self):
+        """Reset sensor, turn on first if required."""
+        self.on()
+        self.set_mode(self.RESET)
+
+    def set_mode(self, mode):
+        """Set sensor mode."""
+        self.mode = mode
+        self.bus.writeto(self.addr, bytes([self.mode]))
+
+    def luminance(self, mode):
+        """Sample luminance (in lux), using specified sensor mode."""
+        # continuous modes
+        if mode & 0x10 and mode != self.mode:
+            self.set_mode(mode)
+        # one shot modes
+        if mode & 0x20:
+            self.set_mode(mode)
+        # earlier measurements return previous reading
+        sleep_ms(24 if mode in (0x13, 0x23) else 180)
+        data = self.bus.readfrom(self.addr, 2)
+        factor = 2.0 if mode in (0x11, 0x21) else 1.0
+        return (data[0]<<8 | data[1]) / (1.2 * factor)