veml7700.py

   1 from machine import I2C, Pin
   2 import time
   3 from micropython import const
   4
   5 #start const
   6 # default address
   7 addr = const(0x10)
   8
   9 # Write registers
  10 als_conf_0 = const(0x00)
  11 als_WH = const(0x01)
  12 als_WL = const(0x02)
  13 pow_sav = const(0x03)
  14
  15 # Read registers
  16 als = const(0x04)
  17 white = const(0x05)
  18 interrupt = const(0x06)
  19
  20 #gain            0.125                    0.25                    1                        2                         integration time
  21 confValues = {  25: {1/8: bytearray([0x00, 0x13]), 1/4: bytearray([0x00,0x1B]), 1: bytearray([0x00, 0x01]), 2: bytearray([0x00, 0x0B])}, #25
  22                 50: {1/8: bytearray([0x00, 0x12]), 1/4: bytearray([0x00,0x1A]), 1: bytearray([0x00, 0x02]), 2: bytearray([0x00, 0x0A])}, #50
  23                 100:{1/8: bytearray([0x00, 0x10]), 1/4: bytearray([0x00,0x18]), 1: bytearray([0x00, 0x00]), 2: bytearray([0x00, 0x08])}, #100
  24                 200:{1/8: bytearray([0x40, 0x10]), 1/4: bytearray([0x40,0x18]), 1: bytearray([0x40, 0x00]), 2: bytearray([0x40, 0x08])}, #200
  25                 400:{1/8: bytearray([0x80, 0x10]), 1/4: bytearray([0x80,0x18]), 1: bytearray([0x80, 0x00]), 2: bytearray([0x80, 0x08])}, #400
  26                 800:{1/8: bytearray([0xC0, 0x10]), 1/4: bytearray([0xC0,0x18]), 1: bytearray([0xC0, 0x00]), 2: bytearray([0xC0, 0x08])}} #800
  27
  28 #gain               0.125,  0.25,   1,      2       integration time
  29 gainValues = {  25: {1/8: 1.8432, 1/4: 0.9216, 1: 0.2304, 2: 0.1152}, #25
  30                 50: {1/8: 0.9216, 1/4: 0.4608, 1: 0.1152, 2: 0.0576}, #50
  31                 100:{1/8: 0.4608, 1/4: 0.2304, 1: 0.0288, 2: 0.0144}, #100
  32                 200:{1/8: 0.2304, 1/4: 0.1152, 1: 0.0288, 2: 0.0144}, #200
  33                 400:{1/8: 0.1152, 1/4: 0.0576, 1: 0.0144, 2: 0.0072}, #400
  34                 800:{1/8: 0.0876, 1/4: 0.0288, 1: 0.0072, 2: 0.0036}} #800
  35
  36
  37 # fin des constante
  38
  39 # Reference data sheet Table 1 for configuration settings
  40
  41 interrupt_high = bytearray([0x00, 0x00]) # Clear values
  42 # Reference data sheet Table 2 for High Threshold
  43
  44 interrupt_low = bytearray([0x00, 0x00]) # Clear values
  45 # Reference data sheet Table 3 for Low Threshold
  46
  47 power_save_mode= bytearray([0x00, 0x00]) # clear values
  48 # Reference data sheet Table 4 for Power Saving Modes
  49
  50
  51 class VEML7700:
  52
  53     def __init__(self,
  54                  address=addr,
  55                  i2c=None,
  56                  it=25,
  57                  gain=1/8,
  58                  **kwargs):
  59
  60         self.address = address
  61         if i2c is None:
  62             raise ValueError('An I2C object is required.')
  63         self.i2c = i2c
  64
  65         confValuesForIt = confValues.get(it)
  66         gainValuesForIt = gainValues.get(it)
  67         if confValuesForIt is not None and gainValuesForIt is not None:
  68             confValueForGain = confValuesForIt.get(gain)
  69             gainValueForGain = gainValuesForIt.get(gain)
  70             if confValueForGain is not None and gainValueForGain is not None:
  71                 self.confValues = confValueForGain
  72                 self.gain = gainValueForGain
  73             else:
  74                 raise ValueError('Wrong gain value. Use 1/8, 1/4, 1, 2')
  75         else:
  76             raise ValueError('Wrong integration time value. Use 25, 50, 100, 200, 400, 800')
  77
  78         self.init()
  79
  80     def init(self):
  81
  82         # load calibration data
  83         #self.i2c.writeto_mem(self.address, als_conf_0, bytearray([0x00,0x13]) )
  84         self.i2c.writeto_mem(self.address, als_conf_0, self.confValues )
  85         self.i2c.writeto_mem(self.address, als_WH, interrupt_high )
  86         self.i2c.writeto_mem(self.address, als_WL, interrupt_low)
  87         self.i2c.writeto_mem(self.address, pow_sav, power_save_mode)
  88
  89     def detect(self):
  90         """ Functions is  verified is  module has detecedself.
  91         this function not implemented for this time
  92         """
  93         None
  94
  95     def read_lux(self):
  96         """ Reads the data from the sensor and returns the data.
  97
  98             Returns:
  99                the number of lux detect by this captor.
 100         """
 101         #The frequency to read the sensor should be set greater than
 102         # the integration time (and the power saving delay if set).
 103         # Reading at a faster frequency will not cause an error, but
 104         # will result in reading the previous data
 105
 106         self.lux = bytearray(2)
 107
 108         time.sleep(.04)  # 40ms
 109
 110         self.i2c.readfrom_mem_into(self.address, als, self.lux)
 111         self.lux= self.lux[0]+self.lux[1]*256
 112         self.lux=self.lux*self.gain
 113         return(int(round(self.lux,0)))