I2C串列通訊實作Part2 – BH1750 微型數位光強度光照感測器

I²C串列通訊實作Part2 – BH1750 微型數位光強度光照感測器

感測器簡介

BH1750 Pin Configuration

Pin Number	Pin Name	Description
1	VCC	Power supply for the module can be 2.4V to 3.6V, typically 3.0V is used
2	GND	Ground of the module, connected to ground of the circuit
3	SCL	Serial Clock Line, used to provide clock pulse for I2C communication
4	SDA	Serial Data Address, used to transfer the data through I2C communication
5	ADDR	Device address pin, used to  select the address when more than two modules are connected

電路圖

程式列表

• BH1750.py

""" Micropython BH1750 ambient light sensor driver. """ import utime   class BH1750():   # Define some constants from the datasheet   POWER_DOWN = 0x00 # No active state   POWER_ON   = 0x01 # Power on   RESET      = 0x07 # Reset data register value     # modes   # Start measurement at 4lx resolution. Time typically 16ms.   CONTINUOUS_LOW_RES_MODE = 0x13   # Start measurement at 1lx resolution. Time typically 120ms   CONTINUOUS_HIGH_RES_MODE_1 = 0x10   # Start measurement at 0.5lx resolution. Time typically 120ms   CONTINUOUS_HIGH_RES_MODE_2 = 0x11   # Start measurement at 1lx resolution. Time typically 120ms   # Device is automatically set to Power Down after measurement.   ONE_TIME_HIGH_RES_MODE_1 = 0x20   # Start measurement at 0.5lx resolution. Time typically 120ms   # Device is automatically set to Power Down after measurement.   ONE_TIME_HIGH_RES_MODE_2 = 0x21   # Start measurement at 1lx resolution. Time typically 120ms   # Device is automatically set to Power Down after measurement.   ONE_TIME_LOW_RES_MODE = 0x23     """ Implement BH1750 communication. """   # 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.power_down()     self.reset()     def _set_mode(self, mode):     """Set sensor mode."""     self.mode = mode     self.bus.write(1,self.addr, self.mode,1,1)     def power_down(self):     """Turn sensor off."""     self._set_mode(self.POWER_DOWN)     def power_on(self):     """Turn sensor on."""     self._set_mode(self.POWER_ON)     def reset(self):     """Reset sensor, turn on first if required."""     self.power_on() #It has to be powered on before resetting     self._set_mode(self.RESET)     def cont_low_res(self):     self._set_mode(self.CONTINUOUS_LOW_RES_MODE)     def cont_high_res(self):     self._set_mode(self.CONTINUOUS_HIGH_RES_MODE_1)     def cont_high_res2(self):     self._set_mode(self.CONTINUOUS_HIGH_RES_MODE_2)     def oneshot_low_res(self):     self._set_mode(self.ONE_TIME_LOW_RES_MODE)     def oneshot_high_res(self):     self._set_mode(self.ONE_TIME_HIGH_RES_MODE_1)     def oneshot_high_res2(self):     self._set_mode(self.ONE_TIME_HIGH_RES_MODE_2)     def luminance(self, mode):     """Sample luminance (in lux), using specified sensor mode."""     data = bytearray(2)     # 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     utime.sleep_ms(24 if mode in (0x13, 0x23) else 180)     self.bus.read(1,self.addr,data,2,1)   # 讀取2個字節     factor = 2.0 if mode in (0x11, 0x21) else 1.0     #print("%x,%x"%(data[0],data[1])) #Debug     return ((data[0]<<8 | data[1]) / (1.2 * factor))

 

• epy_BH1750.py

""" ------------  3V3   VCC  GND   GND  P19   SCL  P20   SDA        ADDR """   from micropython import const from machine import KEY  #獲取按鍵KEY庫 from machine import I2C, PIN import utime import BH1750   i2c_1 = None addrBH1750 = const(0x23)   # BH1750 Device ID address for slave target level = 0   # Start Function if __name__=="__main__":   # Declaration I2C   i2c_1 = I2C(1,100000)      #創建頻率為100kHz的I2C外設,選擇要使用的外設I2C 1   sensor = BH1750.BH1750(i2c_1)   key_c = KEY(KEY.KEYC)    #創建按鍵C   print("Start light measurement.")     try:     while True:       level = sensor.luminance(sensor.ONE_TIME_HIGH_RES_MODE_1)       print("Light Level :%d"%(level))       utime.sleep(1)       if key_c.value() == 0:      #如果按鍵C被按下         break     except:     pass     i2c_1.deinit()   print("Exit light measurement.")

 

執行結果

Start light measurement. Light Level :1050 lx Light Level :1040 lx Light Level :1051 lx Light Level :1035 lx Light Level :1042 lx Exit light measurement.