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() |
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