Source code for MPL3115A2
#!/usr/bin/env python
__author__ = "D.Qendri"
__copyright__ = "Copyright 2015 Sensorian"
__license__ = "GPL V3"
__version__ = "1.0"
import sys
import smbus
import time
import math
from ctypes import *
MPL = CDLL("./libMPL.so")
MPL3115A2_ADDRESS = 0x60 #7-bit I2C address for sensor
#Sensor Memory map
STATUS = 0x00
OUT_P_MSB = 0x01
OUT_P_CSB = 0x02
OUT_P_LSB = 0x03
OUT_T_MSB = 0x04
OUT_T_LSB = 0x05
DR_STATUS = 0x06
OUT_P_DELTA_MSB = 0x07
OUT_P_DELTA_CSB = 0x08
OUT_P_DELTA_LSB = 0x09
OUT_T_DELTA_MSB = 0x0A
OUT_T_DELTA_LSB = 0x0B
WHO_AM_I = 0x0C
F_STATUS = 0x0D
F_DATA = 0x0E
F_SETUP = 0x0F
TIME_DLY = 0x10
SYSMOD = 0x11
INT_SOURCE = 0x12
PT_DATA_CFG = 0x13
BAR_IN_MSB = 0x14
BAR_IN_LSB = 0x15
P_TGT_MSB = 0x16
P_TGT_LSB = 0x17
T_TGT = 0x18
P_WND_MSB = 0x19
P_WND_LSB = 0x1A
T_WND = 0x1B
P_MIN_MSB = 0x1C
P_MIN_CSB = 0x1D
P_MIN_LSB = 0x1E
T_MIN_MSB = 0x1F
T_MIN_LSB = 0x20
P_MAX_MSB = 0x21
P_MAX_CSB = 0x22
P_MAX_LSB = 0x23
T_MAX_MSB = 0x24
T_MAX_LSB = 0x25
CTRL_REG1 = 0x26
CTRL_REG2 = 0x27
CTRL_REG3 = 0x28
CTRL_REG4 = 0x29
CTRL_REG5 = 0x2A
OFF_P = 0x2B
OFF_T = 0x2C
OFF_H = 0x2D
#*********************Status **************************************/
PTDR = 0x04 #Pressure/Altitude OR Temperature data ready
PDR = 0x02 #Pressure/Altitude new data available
TDR = 0x01 #Temperature new Data Available.
#*********************Control Register 1****************************/
ALT = 0x80
RAW = 0x40
OS2 = 0x20
OS1 = 0x10
OS0 = 0x08
RST = 0x04
OST = 0x02
SBYB = 0x01 #Active mode
# Oversample Ratio 1
OS_1 = 0x00 # 6 ms min between samples
OS_2 = OS0 # 10 ms
OS_4 = OS1 # 18 ms
OS_8 = OS1 | OS0 # 34 ms
OS_16 = OS2 # 66 ms
OS_32 = OS2 | OS0 # 130 ms
OS_64 = OS2 | OS1 # 258 ms
OS_128 = OS2 | OS1 | OS2 # 512 ms
BAR_MASK = 0x80
ALT_MASK = 0xEF
ACTIVE_MASK = 0xF1
STANDBY_MASK = 0xFE
#*********************Control Register 5****************************/
DISABLED = 0x00
CIRCULAR = 0x40
FULL_STOP = 0x80
F_MODE = DISABLED
#*****************PT_DATA_CFG - Sensor data event flag register***********/
DREM = 0x04 # Data Ready Event Mode
PDEFE = 0x02 # Pressure Data Event Flag Enabled
TDEFE = 0x01 # Temperature Data Event Flag Enabled
[docs]class MPL3115A2(object):
def __init__(self):
"""
Initializes I2C bus if not initizalized and configures sensor in active mode.
:param none:
:returns: none
"""
self._address = MPL3115A2_ADDRESS
MPL.I2C_Initialize()
MPL.MPL3115A2_Initialize()
[docs] def GetMode(self):
"""
Return a bool value indicating wheather the sensor is in Active or Standby mode.
:param none:
:returns: Mode - 1 if in Active mode, 0 otherwise
"""
return MPL.MPL3115A2_Mode()
[docs] def GetID(self):
"""
Returns the Factory Sensor ID.
:param none:
:returns: id - Factory ID
"""
a = MPL.MPL3115A2_ID()
return int(a)
[docs] def ReadBarometricPressure(self):
"""
Reads the current pressure in Pa.
:param none:
:returns: current pressure or -1 if no new data is available
"""
# return sensor.MPL3115A2_ReadBarometricPressure()
status = MPL.MPL3115A2_ReadByte(self._address,STATUS)
#Check PDR bit, if it's not set then toggle OST
if((status & (1<< PDR)) == 0):
MPL.MPL3115A2_ToggleOneShot() #Toggle the OST bit causing the sensor to immediately take another reading
m_pressure = MPL.MPL3115A2_ReadByte(self._address,OUT_P_MSB)
c_pressure = MPL.MPL3115A2_ReadByte(self._address,OUT_P_CSB)
l_pressure = MPL.MPL3115A2_ReadByte(self._address,OUT_P_LSB)
pressure_whole = long (m_pressure<<16) | long(c_pressure<<8) | long (l_pressure) # Pressure comes back as a left shifted 20 bit number
pressure_whole >>= 6 #Pressure is an 18 bit number with 2 bits of decimal. Get rid of decimal portion.
c_pressure &= 0b00110000 # Bits 5/4 represent the fractional component
c_pressure >>= 4 # Get it right aligned
pressure_decimal = float(((c_pressure&0x30)>>4)/4.0) # Turn it into fraction
pressure = float(pressure_whole + pressure_decimal)
return pressure
[docs] def ReadTemperature(self):
"""
Reads the current temperature in degrees Celcius.
:param none:
:returns: temp - Returns temperature as a float.
"""
# return sensor.MPL3115A2_ReadTemperature()
t_MSB = MPL.MPL3115A2_ReadByte(self._address,OUT_T_MSB)
t_LSB = MPL.MPL3115A2_ReadByte(self._address,OUT_T_LSB)
templsb = float((t_LSB >>4) / 16.0) #temp, fraction of a degree
temperature = float(t_MSB + templsb) #
return temperature
[docs] def BarometerMode(self):
"""
Sets the sensor in Barometer mode.
:param none:
:returns: none
"""
MPL.MPL3115A2_BarometerMode()
[docs] def AltimeterMode(self):
"""
Sets the mode in Altimeter mode.
:param none:
:returns: none
"""
ctrl_reg = MPL.MPL3115A2_ReadByte(self._address,CTRL_REG1) #Read current settings
ctrl_reg &= ~(SBYB) #Go to Standby mode
MPL.MPL3115A2_WriteByte(self._address,CTRL_REG1, ctrl_reg)
ctrl_reg = ALT|OS_128 #Set ALT bit to one and enable back Active mode
MPL.MPL3115A2_WriteByte(self._address,CTRL_REG1, ctrl_reg)
[docs] def ReadAltitude(self):
"""
Returns the number of meters above sea level.
:param none:
:returns: altitude as a float
"""
m_altitude = MPL.MPL3115A2_ReadByte(self._address,OUT_P_MSB) #Read altitude data
c_altitude = MPL.MPL3115A2_ReadByte(self._address,OUT_P_CSB)
l_altitude = MPL.MPL3115A2_ReadByte(self._address,OUT_P_LSB)
altitude = ((m_altitude << 24) | (c_altitude << 16) | (l_altitude))*10
return( float(altitude/65536))
[docs] def GetAltitude(self):
"""
Returns the number of meters above sea level.
:param none:
:returns: altitude as a float
"""
alt = MPL.MPL3115A2_ReadAltitude()
alt_m = alt >> 8
alt_l = alt & 0xff
if (alt_l > 99):
alt_l = alt_l / 1000.0
else:
alt_l = alt_l / 100.0
return self.twosToInt(alt_m, 16) + alt_l
[docs] def StandbyMode(self):
"""
Puts the sensor in standby mode. This is needed whenever one wants to modify the control registers.
:param none:
:returns: none
"""
MPL.MPL3115A2_StandbyMode()
[docs] def ActiveMode(self):
"""
Put the sensor in active mode.
:param none:
:returns: none
"""
MPL.MPL3115A2_ActiveMode()
[docs] def OversampleRate(self, sampleRate):
"""
Sets the ovsersampling rate.
:param sampleRate: sampleRate is from 0 to 7
:returns: none
"""
MPL.MPL3115A2_OversampleRate()
[docs] def SetAcquisitionTimeStep(self,ST_Value):
"""
Set the acquisition time step.
:param ST_Value: Time Step value
:returns: none
"""
MPL.MPL3115A2_SetAcquisitionTimeStep(ST_Value)
[docs] def EnableEventFlags(self):
"""
Enables the pressure and temp measurement event flags so that we can
test against them. This is recommended in datasheet during setup.
:param none:
:returns: none
"""
MPL.MPL3115A2_enableEventFlags()
[docs] def ToggleOneShot(self):
"""
Clears then sets the OST bit which causes the sensor to immediately take another reading
Needed to sample faster than 1Hz.
:param none:
:returns: none
"""
MPL.MPL3115A2_toggleOneShot()
[docs] def CofigureInterruptPin(self,interrupt,pin):
"""
Configure the interrupt pin.
:param interrupt: Type of interrupt
:param pin: Only pin 1 is used
:returns: none
"""
MPL.MPL3115A2_CofigureInterruptPin()
[docs] def WriteByte(self,address,reg,data):
"""
Write byte value from register.
:param address: Sensor address
:param reg: Register address
:param data: Register value
:returns: none
"""
MPL.I2C_WriteByteRegister(address,reg,data)
[docs] def ReadByte(self,address,reg):
"""
Read byte value from register.
:param address: Sensor address
:param reg: Register address
:returns: byte read from register
"""
MPL.I2C_ReadByteRegister(address,reg)
[docs] def ReadByteArray(self,address, reg, buffer, length):
"""Read a byte array from the sensor.
:param address: Sensor address
:param reg: Register address
:param buffer: Data buffer
:param length: Data length
:returns: array - Byte array
"""
MPL.I2C_ReadByteArray(address,reg,buffer,length)
[docs] def WriteByteArray(self, address, reg, buffer):
"""
Writes an array of bytes to the sensor.
:param address: Sensor address
:param reg: Register address
:param buffer: Data buffer
:param length: buffer length
:returns: none
"""
MPL.MPL3115A2_WriteByteArray(address,reg,buffer,length)
[docs] def TwosToInt(self, val, len):
"""
Convert twos complement to integer.
:param val:
:param len:
:returns: complement - integer value of two's complement
"""
if(val & (1 << len - 1)):
val = val - (1<<len)
