BMP180_Rpi/in_python/bmp180.py

#!/usr/bin/python
#--------------------------------------
#
#           bmp180.py
#  Read data from a digital pressure sensor.
#  And broadcast to local network.
#  Author : Jony Silva
#  Date   : Wed 12 Jul 21:03:26 UTC 2017
#
#  All the credit for the code to read 
#  the chip BMP180 goes to:
#  http://www.raspberrypi-spy.co.uk/
#
#--------------------------------------
import smbus
import time
from socket import *
from ctypes import c_short
 
DEVICE = 0x77 # Default device I2C address

# Interval sending in seconds between broadcasts
SEND_TIMING = 1
 
# addressing information of target
IPADDR = '<broadcast>'
PORTNUM = 10000 
 
#bus = smbus.SMBus(0)  # Rev 1 Pi uses 0
bus = smbus.SMBus(1) # Rev 2 Pi uses 1 
 
def getShort(data, index):
	# return two bytes from data as a signed 16-bit value
	return c_short((data[index] << 8) + data[index + 1]).value

def getUshort(data, index):
	# return two bytes from data as an unsigned 16-bit value
	return (data[index] << 8) + data[index + 1]

def readBmp180(addr=DEVICE):
	# Register Addresses
	REG_CALIB  = 0xAA
	REG_MEAS   = 0xF4
	REG_MSB    = 0xF6
	REG_LSB    = 0xF7
	# Control Register Address
	CRV_TEMP   = 0x2E
	CRV_PRES   = 0x34 
	# Oversample setting
	OVERSAMPLE = 3    # 0 - 3

	# Read calibration data from EEPROM
	cal = bus.read_i2c_block_data(addr, REG_CALIB, 22)

	# Convert byte data to word values
	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)

	# Read temperature
	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

	# Read pressure
	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)

	# Refine temperature
	X1 = ((UT - AC6) * AC5) >> 15
	X2 = (MC << 11) / (X1 + MD)
	B5 = X1 + X2
	temperature = int(B5 + 8) >> 4

	# Refine pressure
	B6  = B5 - 4000
	B62 = int(B6 * B6) >> 12
	X1  = (B2 * B62) >> 11
	X2  = int(AC2 * B6) >> 11
	X3  = X1 + X2
	B3  = (((AC1 * 4 + X3) << OVERSAMPLE) + 2) >> 2

	X1 = int(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 = (int(P) >> 8) * (int(P) >> 8)
	X1 = (X1 * 3038) >> 16
	X2 = int(-7357 * P) >> 16
	pressure = int(P + ((X1 + X2 + 3791) >> 4))

	return (temperature/10.0,pressure/100.0)

def main():
    
	s = socket(AF_INET, SOCK_DGRAM)
	s.setsockopt(SOL_SOCKET, SO_BROADCAST, 1)

	print "Broadcasting Temperature and Pressure on Port:", (PORTNUM)

	while 1:
		(temperature,pressure) = readBmp180()
		temp = "Temperature : {0} C".format(temperature)
		press = "Pressure    : {0} mbar".format(pressure)
		s.sendto(temp+'\n'+press+'\n', (IPADDR, PORTNUM))
		time.sleep(SEND_TIMING)

	 
if __name__=="__main__":
   main()