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BMP180.py
113 lines (98 loc) · 3.23 KB
/
BMP180.py
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from __future__ import print_function
from numpy import int16
import time
def connect(route,**args):
return BMP180(route,**args)
class BMP180:
ADDRESS = 0x77
REG_CONTROL = 0xF4
REG_RESULT = 0xF6
CMD_TEMP = 0x2E
CMD_P0 = 0x34
CMD_P1 = 0x74
CMD_P2 = 0xB4
CMD_P3 = 0xF4
oversampling=0
NUMPLOTS=3
PLOTNAMES = ['Temperature','Pressure','Altitude']
name = 'Altimeter BMP180'
def __init__(self,I2CRead, I2CWrite, **args):
self.ADDRESS = args.get('address',self.ADDRESS)
self.I2CReadBulk = I2CRead
self.I2CWriteBulk = I2CWrite
self.MB = self.__readInt__(0xBA)
self.c3 = 160.0 * pow(2,-15) * self.__readInt__(0xAE)
self.c4 = pow(10,-3) * pow(2,-15) * self.__readUInt__(0xB0)
self.b1 = pow(160,2) * pow(2,-30) * self.__readInt__(0xB6)
self.c5 = (pow(2,-15) / 160) * self.__readUInt__(0xB2)
self.c6 = self.__readUInt__(0xB4)
self.mc = (pow(2,11) / pow(160,2)) * self.__readInt__(0xBC)
self.md = self.__readInt__(0xBE) / 160.0
self.x0 = self.__readInt__(0xAA)
self.x1 = 160.0 * pow(2,-13) * self.__readInt__(0xAC)
self.x2 = pow(160,2) * pow(2,-25) * self.__readInt__(0xB8)
self.y0 = self.c4 * pow(2,15)
self.y1 = self.c4 * self.c3
self.y2 = self.c4 * self.b1
self.p0 = (3791.0 - 8.0) / 1600.0
self.p1 = 1.0 - 7357.0 * pow(2,-20)
self.p2 = 3038.0 * 100.0 * pow(2,-36)
self.T=25
print ('calib:',self.c3,self.c4,self.b1,self.c5,self.c6,self.mc,self.md,self.x0,self.x1,self.x2,self.y0,self.y1,self.p0,self.p1,self.p2)
self.params={'setOversampling':[0,1,2,3]}
self.name='BMP180 Altimeter'
self.initTemperature()
self.readTemperature()
self.initPressure()
self.baseline=self.readPressure()
def __readInt__(self,addr):
return int16(self.__readUInt__(addr))
def __readUInt__(self,addr):
vals = self.I2CReadBulk(self.ADDRESS,addr,2)
v=1.*((vals[0]<<8)|vals[1])
return v
def initTemperature(self):
self.I2CWriteBulk(self.ADDRESS,[self.REG_CONTROL,self.CMD_TEMP])
time.sleep(0.005)
def readTemperature(self):
vals = self.I2CReadBulk(self.ADDRESS,self.REG_RESULT,2)
if vals:
if len(vals)==2:
T = (vals[0] <<8 ) + vals[1]
a = self.c5 * (T - self.c6)
self.T = a + (self.mc / (a + self.md))
return self.T
return False
def setOversampling(self,num):
self.oversampling=num
def initPressure(self):
os = [0x34,0x74,0xb4,0xf4]
delays=[0.005,0.008,0.014,0.026]
self.I2CWriteBulk(self.ADDRESS,[self.REG_CONTROL,os[self.oversampling] ])
time.sleep(delays[self.oversampling])
def readPressure(self):
vals = self.I2CReadBulk(self.ADDRESS,self.REG_RESULT,3)
if len(vals)==3:
P = 1.*(vals[0] <<8) + vals[1] + (vals[2]/256.0)
s = self.T - 25.0
x = (self.x2 * pow(s,2)) + (self.x1 * s) + self.x0
y = (self.y2 * pow(s,2)) + (self.y1 * s) + self.y0
z = (P - x) / y
self.P = (self.p2 * pow(z,2)) + (self.p1 * z) + self.p0
return self.P
else:
return False
def altitude(self):
#baseline pressure needs to be provided
return (44330.0*(1-pow(self.P/self.baseline,1/5.255)))
def sealevel(self,P,A):
'''
given a calculated pressure and altitude, return the sealevel
'''
return(P/pow(1-(A/44330.0),5.255))
def getRaw(self):
self.initTemperature()
self.readTemperature()
self.initPressure()
self.readPressure()
return [self.T,self.P,self.altitude()]