# Distributed with a free-will license. # Use it any way you want, profit or free, provided it fits in the licenses of its associated works. # BMP180 # This code is designed to work with the BMP180_I2CS I2C Mini Module available from ControlEverything.com. # https://www.controleverything.com/content/Pressure?sku=BMP180_I2CS#tabs-0-product_tabset-2 import smbus import threading import time from . import logger class bmp_180(object): KEY_TEMPERATURE = 'temperature' KEY_PRESSURE = 'pressure' KEY_TIME = 'time' def __init__(self, data_callback=None): self.__data_callback__ = data_callback # Initial the dht device, with data pin connected to: self.__active__ = True self.__thread__ = threading.Thread(target=self.run, args=()) self.__thread__.daemon = True # Daemonize thread self.__thread__.start() # Start the execution def run(self): while self.__active__: data = self.__bmp_data_transmission__() if data is not None: logger.debug('BMP-Communication: Successfully: %s', repr(data)) if self.__data_callback__ is not None: self.__data_callback__(**data) time.sleep(0.5) def close(self): self.__active__ = False self.__thread__.join() def __del__(self): self.close() def __bmp_data_transmission__(self): rv = {} # Get I2C bus bus = smbus.SMBus(1) # BMP180 address, 0x77(119) # Read data back from 0xAA(170), 22 bytes data = bus.read_i2c_block_data(0x77, 0xAA, 22) # Convert the data AC1 = data[0] * 256 + data[1] if AC1 > 32767 : AC1 -= 65535 AC2 = data[2] * 256 + data[3] if AC2 > 32767 : AC2 -= 65535 AC3 = data[4] * 256 + data[5] if AC3 > 32767 : AC3 -= 65535 AC4 = data[6] * 256 + data[7] AC5 = data[8] * 256 + data[9] AC6 = data[10] * 256 + data[11] B1 = data[12] * 256 + data[13] if B1 > 32767 : B1 -= 65535 B2 = data[14] * 256 + data[15] if B2 > 32767 : B2 -= 65535 MB = data[16] * 256 + data[17] if MB > 32767 : MB -= 65535 MC = data[18] * 256 + data[19] if MC > 32767 : MC -= 65535 MD = data[20] * 256 + data[21] if MD > 32767 : MD -= 65535 time.sleep(0.5) # BMP180 address, 0x77(119) # Select measurement control register, 0xF4(244) # 0x2E(46) Enable temperature measurement bus.write_byte_data(0x77, 0xF4, 0x2E) time.sleep(0.5) # BMP180 address, 0x77(119) # Read data back from 0xF6(246), 2 bytes # temp MSB, temp LSB data = bus.read_i2c_block_data(0x77, 0xF6, 2) # Convert the data temp = data[0] * 256 + data[1] # BMP180 address, 0x77(119) # Select measurement control register, 0xF4(244) # 0x74(116) Enable pressure measurement, OSS = 1 bus.write_byte_data(0x77, 0xF4, 0x74) time.sleep(0.5) # BMP180 address, 0x77(119) # Read data back from 0xF6(246), 3 bytes # pres MSB1, pres MSB, pres LSB data = bus.read_i2c_block_data(0x77, 0xF6, 3) rv[self.KEY_TIME] = time.time() # Convert the data pres = ((data[0] * 65536) + (data[1] * 256) + data[2]) / 128 # Callibration for Temperature X1 = (temp - AC6) * AC5 / 32768.0 X2 = (MC * 2048.0) / (X1 + MD) B5 = X1 + X2 rv[self.KEY_TEMPERATURE] = ((B5 + 8.0) / 16.0) / 10.0 # Calibration for Pressure B6 = B5 - 4000 X1 = (B2 * (B6 * B6 / 4096.0)) / 2048.0 X2 = AC2 * B6 / 2048.0 X3 = X1 + X2 B3 = (((AC1 * 4 + X3) * 2) + 2) / 4.0 X1 = AC3 * B6 / 8192.0 X2 = (B1 * (B6 * B6 / 2048.0)) / 65536.0 X3 = ((X1 + X2) + 2) / 4.0 B4 = AC4 * (X3 + 32768) / 32768.0 B7 = ((pres - B3) * (25000.0)) pressure = 0.0 if B7 < 2147483648: pressure = (B7 * 2) / B4 else : pressure = (B7 / B4) * 2 X1 = (pressure / 256.0) * (pressure / 256.0) X1 = (X1 * 3038.0) / 65536.0 X2 = ((-7357) * pressure) / 65536.0 rv[self.KEY_PRESSURE] = (pressure + (X1 + X2 + 3791) / 16.0) / 100 return rv