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bmp085.py
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import smbus
import time
bus = smbus.SMBus(1)
class BMP085:
ADDR = 0x77
OSS = 0
ac1 = None
ac2 = None
ac3 = None
ac4 = None
ac5 = None
ac6 = None
b1 = None
b2 = None
mb = None
mc = None
md = None
b5 = None
def init(self):
reg_data = bus.read_i2c_block_data(self.ADDR, 0xAA, 22)
self.ac1 = reg_data[0] << 8 | reg_data[1]
if self.ac1 > 35676:
self.ac1 -= 65536
self.ac2 = reg_data[2] << 8 | reg_data[3]
if self.ac2 > 35676:
self.ac2 -= 65536
self.ac3 = reg_data[4] << 8 | reg_data[5]
if self.ac3 > 35676:
self.ac3 -= 65536
self.ac4 = reg_data[6] << 8 | reg_data[7]
self.ac5 = reg_data[8] << 8 | reg_data[9]
self.ac6 = reg_data[10] << 8 | reg_data[11]
self.b1 = reg_data[12] << 8 | reg_data[13]
if self.b1 > 35676:
self.b1 -= 65536
self.b2 = reg_data[14] << 8 | reg_data[15]
if self.b2 > 35676:
self.b2 -= 65536
self.mb = reg_data[16] << 8 | reg_data[17]
if self.mb > 35676:
self.mb -= 65536
self.mc = reg_data[18] << 8 | reg_data[19]
if self.mc > 35676:
self.mc -= 65536
self.md = reg_data[20] << 8 | reg_data[21]
if self.md > 35676:
self.md -= 65536
def get_temperature(self):
ut = self.read_ut()
x1 = ((ut - self.ac6) * self.ac5) >> 15
x2 = int((self.mc << 11) / (x1 + self.md))
self.b5 = x1 + x2
return (self.b5 + 8) >> 4
def get_pressure(self):
up = self.read_up()
b6 = self.b5 - 4000
x1 = (self.b2 * ((b6 * b6) >> 12)) >> 11
x2 = (self.ac2 * b6) >> 11
x3 = x1 + x2
b3 = (((self.ac1 * 4 + x3) << self.OSS) + 2) >> 2
x1 = (self.ac3 * b6) >> 13
x2 = (self.b1 * ((b6 * b6) >> 12)) >> 16
x3 = ((x1 + x2) + 2) >> 2
b4 = (self.ac4 * (x3 + 32768)) >> 15
b7 = (up - b3) * (50000 >> self.OSS)
if b7 < 0x80000000:
p = int((b7 << 1) / b4)
else:
p = int(b7 / b4) << 1
x1 = (p >> 8) * (p >> 8)
x1 = (x1 * 3038) >> 16
x2 = (-7357 * p) >> 16
p += (x1 + x2 + 3791) >> 4
return p
def read_ut(self):
bus.write_byte_data(self.ADDR, 0xF4, 0x2E)
time.sleep(4.5 / 1000)
reg_data = bus.read_i2c_block_data(self.ADDR, 0xF6, 2)
return reg_data[0] << 8 | reg_data[1]
def read_up(self):
bus.write_byte_data(self.ADDR, 0xF4, 0x34 + (self.OSS << 6))
time.sleep((2 + (3 << self.OSS)) / 1000)
reg_data = bus.read_i2c_block_data(self.ADDR, 0xF6, 3)
up = ((reg_data[0] << 16) | (reg_data[1] << 8) | reg_data[2]) >> (8 - self.OSS)
return up
def read(self):
return self.get_temperature(), self.get_pressure()
def main():
bmp = BMP085()
bmp.init()
try:
while True:
print(bmp.get_temperature())
print(bmp.get_pressure())
print()
time.sleep(1)
except KeyboardInterrupt:
print()
pass
print('Done.')
if __name__ == '__main__':
main()