init

UI/bmp180.py

@@ -0,0 +1,142 @@
+#!/usr/bin/python
+# --------------------------------------
+#    ___  ___  _ ____
+#   / _ \/ _ \(_) __/__  __ __
+#  / , _/ ___/ /\ \/ _ \/ // /
+# /_/|_/_/  /_/___/ .__/\_, /
+#                /_/   /___/
+#
+#           bmp180.py
+#  Read data from a digital pressure sensor.
+#
+# Author : Matt Hawkins
+# Date   : 17/02/2017
+#
+# http://www.raspberrypi-spy.co.uk/
+#
+# --------------------------------------
+import smbus
+import time
+from ctypes import c_short
+
+DEVICE = 0x77  # Default device I2C address
+
+# bus = smbus.SMBus(0)  # Rev 1 Pi uses 0
+bus = smbus.SMBus(1)  # Rev 2 Pi uses 1
+
+
+def convertToString(data):
+    # Simple function to convert binary data into
+    # a string
+    return str((data[1] + (256 * data[0])) / 1.2)
+
+
+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 readBmp180Id(addr=DEVICE):
+    # Chip ID Register Address
+    REG_ID = 0xD0
+    (chip_id, chip_version) = bus.read_i2c_block_data(addr, REG_ID, 2)
+    return (chip_id, chip_version)
+
+
+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
+    # 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():
+
+    #(chip_id, chip_version) = readBmp180Id()
+    #print("Chip ID     : {0}".format(chip_id))
+    #print("Version     : {0}".format(chip_version))
+
+    # print
+
+    (temperature, pressure) = readBmp180()
+    #print("Temperature : {0} C".format(temperature))
+    #print("Pressure    : {0} mbar".format(pressure))
+    return {"temperature": temperature, "pressure": pressure}
+
+
+def readings():
+    (temperature, pressure) = readBmp180()
+    return pressure
+
+
+# if __name__ == "__main__":
+#     main()