Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
BMP180 luchtdruk + temperatuur sensor (Raspberry Pi)
#!/usr/bin/python
# BMP180 luchtdruk + temperatuur sensor
# https://www.raspberrytips.nl
import smbus
import time
from ctypes import c_short
DEVICE = 0x77
bus = smbus.SMBus(1)
def convertToString(data):
return str((data[1] + (256 * data[0])) / 1.2)
def getShort(data, index):
return c_short((data[index] << 8) + data[index + 1]).value
def getUshort(data, index):
return (data[index] << 8) + data[index + 1]
def readBmp180(addr=DEVICE):
REG_CALIB = 0xAA
REG_MEAS = 0xF4
REG_MSB = 0xF6
REG_LSB = 0xF7
CRV_TEMP = 0x2E
CRV_PRES = 0x34
OVERSAMPLE = 3
cal = bus.read_i2c_block_data(addr, REG_CALIB, 22)
AC1 = getShort(cal, 0)
AC2 = getShort(cal, 2)
AC3 = getShort(cal, 4)
AC4 = getUshort(cal, 6)
AC5 = getUshort(cal, 8)
AC6 = getUshort(cal, 10)
B1 = getShort(cal, 12)
B2 = getShort(cal, 14)
MB = getShort(cal, 16)
MC = getShort(cal, 18)
MD = getShort(cal, 20)
# Lees Temperatuur
bus.write_byte_data(addr, REG_MEAS, CRV_TEMP)
time.sleep(0.005)
(msb, lsb) = bus.read_i2c_block_data(addr, REG_MSB, 2)
UT = (msb << 8) + lsb
# Lees Luchtdruk
bus.write_byte_data(addr, REG_MEAS, CRV_PRES + (OVERSAMPLE << 6))
time.sleep(0.04)
(msb, lsb, xsb) = bus.read_i2c_block_data(addr, REG_MSB, 3)
UP = ((msb << 16) + (lsb << 8) + xsb) >> (8 - OVERSAMPLE)
# Opmaak temperatuur
X1 = ((UT - AC6) * AC5) >> 15
X2 = (MC << 11) / (X1 + MD)
B5 = X1 + X2
temperature = (B5 + 8) >> 4
# Opmaak luchtdruk
B6 = B5 - 4000
B62 = B6 * B6 >> 12
X1 = (B2 * B62) >> 11
X2 = AC2 * B6 >> 11
X3 = X1 + X2
B3 = (((AC1 * 4 + X3) << OVERSAMPLE) + 2) >> 2
X1 = AC3 * B6 >> 13
X2 = (B1 * B62) >> 16
X3 = ((X1 + X2) + 2) >> 2
B4 = (AC4 * (X3 + 32768)) >> 15
B7 = (UP - B3) * (50000 >> OVERSAMPLE)
P = (B7 * 2) / B4
X1 = (P >> 8) * (P >> 8)
X1 = (X1 * 3038) >> 16
X2 = (-7357 * P) >> 16
pressure = P + ((X1 + X2 + 3791) >> 4)
return (temperature/10.0,pressure/ 100.0)
def main():
deg = u'\xb0'
(temperature,pressure)=readBmp180()
print "Temperatuur : ", temperature,deg.encode('utf8'), "C"
print "Luchtdruk : ", pressure, "mbar"
if __name__=="__main__":
main()
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.