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