这是社区的microbit库中一个，可以方便的通过I2C接口读取BMP280气压传感器的数据。

基本用法：

from microbit import *
import bmp280
 
b = bmp280.BMP280()
 
while True:
    sle ep(500)
    b.get()

网址：

• https://github.com/shaoziyang/microbit-lib/tree/master/sensor/bmp280
• https://gitee.com/microbit/microbit-lib/tree/master/sensor/bmp280

完整驱动：

'''
	microbit drive for BMP280 Digital Pressure Sensor
	Author: shaoziyang
	Date:   2018.2
	http://www.micropython.org.cn
'''
from microbit import i2c
 
BMP280_I2C_ADDR = 0x76
 
class BMP280():
	def __init__(self):
		self._T1 = self._g2r(0x88)
		self._T2 = self.short(self._g2r(0x8A))
		self._T3 = self.short(self._g2r(0x8C))
		self._P1 = self._g2r(0x8E)
		self._P2 = self.short(self._g2r(0x90))
		self._P3 = self.short(self._g2r(0x92))
		self._P4 = self.short(self._g2r(0x94))
		self._P5 = self.short(self._g2r(0x96))
		self._P6 = self.short(self._g2r(0x98))
		self._P7 = self.short(self._g2r(0x9A))
		self._P8 = self.short(self._g2r(0x9C))
		self._P9 = self.short(self._g2r(0x9E))
		self._sr(0xF4, 0x2F)
		self._sr(0xF5, 0x0C)
		self.T = 0
		self.P = 0
		self.version = '1.0'
 
	def	short(self,	dat):
		if dat > 32767:
			return dat - 65536
		else:
			return dat
 
	# set reg
	def	_sr(self, reg, dat):
		i2c.write(BMP280_I2C_ADDR, bytearray([reg, dat]))
 
	# get reg
	def	_gr(self, reg):
		i2c.write(BMP280_I2C_ADDR, bytearray([reg]))
		t = i2c.read(BMP280_I2C_ADDR, 1)
		return t[0]
 
	# get two reg
	def	_g2r(self, reg):
		i2c.write(BMP280_I2C_ADDR, bytearray([reg]))
		t = i2c.read(BMP280_I2C_ADDR, 2)
		return t[0] + t[1]*256
 
	def get(self):
		adc_T = (self._gr(0xFA)<<12) + (self._gr(0xFB)<<4) + (self._gr(0xFC)>>4)
		var1 = (((adc_T>>3)-(self._T1<<1))*self._T2)>>11
		var2 = (((((adc_T>>4)-self._T1)*((adc_T>>4) - self._T1))>>12)*self._T3)>>14
		t = var1+var2
		self.T = ((t * 5 + 128) >> 8)/100
		var1 = (t>>1) - 64000
		var2 = (((var1>>2) * (var1>>2)) >> 11 ) * self._P6
		var2 = var2 + ((var1*self._P5)<<1)
		var2 = (var2>>2)+(self._P4<<16)
		var1 = (((self._P3*((var1>>2)*(var1>>2))>>13)>>3) + (((self._P2) * var1)>>1))>>18
		var1 = ((32768+var1)*self._P1)>>15
		if var1 == 0:
			return  # avoid exception caused by division by zero
		adc_P = (self._gr(0xF7)<<12) + (self._gr(0xF8)<<4) + (self._gr(0xF9)>>4)
		p=((1048576-adc_P)-(var2>>12))*3125
		if p < 0x80000000:
			p = (p << 1) // var1
		else:
			p = (p // var1) * 2
		var1 = (self._P9 * (((p>>3)*(p>>3))>>13))>>12
		var2 = (((p>>2)) * self._P8)>>13
		self.P = p + ((var1 + var2 + self._P7) >> 4)
		return [self.T, self.P]
 
	# get Temperature in Celsius
	def Temperature(self):
		self.get()
		return self.T
 
	# get Pressure in Pa
	def Pressure(self):
		self.get()
		return self.P
 
	# Calculating absolute altitude
	def	Altitude(self):
		self.get()
		return 44330*(1-(self.P/101325)**(1/5.255))
 
	# sleep mode
	def poweroff(self):
		self._sr(0xF4, 0)
 
	# normal mode
	def poweron(self):
		self._sr(0xF4, 0x2F)

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