mirror of
https://github.com/supleed2/ELEC60013-ES-CW1.git
synced 2024-09-19 20:06:17 +00:00
124 lines
4.8 KiB
Python
124 lines
4.8 KiB
Python
"""Library for interacting with TMP006 Thermopile (IR Temperature) Sensor."""
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import smbus2
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from time import sleep
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# Pointer Register Locations
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_REG_VOBJ = bytes([0x00])
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_REG_TAMB = bytes([0x01])
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_REG_CNFG = bytes([0x02])
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_REG_M_ID = bytes([0xFE])
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_REG_D_ID = bytes([0xFF])
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# Configuration Flags
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_MODE_ON = bytes([0x70])
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SAMPLERATE_4HZ = bytes([0x00])
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SAMPLERATE_2HZ = bytes([0x02])
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SAMPLERATE_1HZ = bytes([0x04])
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SAMPLERATE_0_5HZ = bytes([0x06])
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SAMPLERATE_0_25HZ = bytes([0x08])
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_DRDY_EN = bytes([0x01])
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class TMP006:
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def __init__(self, i2cBus, i2cAddress=0x40, samplerate=SAMPLERATE_1HZ):
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self.i2c = i2cBus
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self.addr = i2cAddress
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self.samplerate = samplerate
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i2cBus.pec = True # enable smbus2 Packet Error Checking
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self.config = bytes([0x00, 0x00])
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self.config = bytes(
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[self.config[0] | samplerate[0] | _MODE_ON[0] | _DRDY_EN[0], self.config[1]]
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)
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ptrConfig = smbus2.i2c_msg.write(self.addr, _REG_CNFG)
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writeConfig = smbus2.i2c_msg.write(self.addr, self.config)
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self.i2c.i2c_rdwr(ptrConfig, writeConfig)
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@property
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def temperature(self) -> float:
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"""Measured temperature in degrees Celsius, to 2 decimel places"""
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Vobj = self.vObject()
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Tdie = self.tAmbient()
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# Values for Calculations
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S0 = 6.4e-14 # Calibration Factor TODO: Calibrate
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a1 = 1.75e-3
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a2 = -1.678e-5
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Tref = 298.15
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b0 = -2.94e-5
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b1 = -5.7e-7
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b2 = 4.63e-9
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c2 = 13.4
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# Calculate Sensitivity of Thermopile
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S = S0 * (1 + a1 * (Tdie - Tref) + a2 * ((Tdie - Tref) ** 2))
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# Calculate Coltage offset due to package thermal resistance
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Voffset = b0 + b1 * (Tdie - Tref) + b2 * ((Tdie - Tref) ** 2)
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# Calculate Seebeck coefficients
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fVobj = (Vobj - Voffset) + c2 * ((Vobj - Voffset) ** 2)
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# Calculate object temperature in Kelvin
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Tobj = (Tdie**4 + (fVobj / S)) ** 0.25
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# Convert from Kelvin to Celsius
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return round(Tobj - 273.15, 2)
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@property
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def active(self) -> bool:
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"""Check if Sensor is powered on."""
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ptrPower = smbus2.i2c_msg.write(self.addr, _REG_CNFG)
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power = smbus2.i2c_msg.read(self.addr, 2)
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self.i2c.i2c_rdwr(ptrPower, power)
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return power.buf[0][0] & _MODE_ON[0] != 0
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@active.setter
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def active(self, value: bool):
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"""Set the sensor to active or inactive."""
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if value:
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ptrPower = smbus2.i2c_msg.write(self.addr, _REG_CNFG)
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power = smbus2.i2c_msg.read(self.addr, 2)
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self.i2c.i2c_rdwr(ptrPower, power)
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newPower = bytes([power.buf[0][0] | _MODE_ON[0], power.buf[1][0]])
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updatePower = smbus2.i2c_msg.write(self.addr, newPower)
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self.i2c.i2c_rdwr(ptrPower, updatePower)
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else:
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ptrPower = smbus2.i2c_msg.write(self.addr, _REG_CNFG)
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power = smbus2.i2c_msg.read(self.addr, 2)
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self.i2c.i2c_rdwr(ptrPower, power)
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newPower = bytes([power.buf[0][0] & ~_MODE_ON[0], power.buf[1][0]])
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updatePower = smbus2.i2c_msg.write(self.addr, newPower)
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self.i2c.i2c_rdwr(ptrPower, updatePower)
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def vObject(self) -> float:
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"""Reading from Sensor Voltage Register in Volts"""
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ptrVobject = smbus2.i2c_msg.write(self.addr, _REG_VOBJ)
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readVobject = smbus2.i2c_msg.read(self.addr, 2)
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self.i2c.i2c_rdwr(ptrVobject, readVobject)
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scaledVoltage = int.from_bytes(
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readVobject.buf[0] + readVobject.buf[1], byteorder="big", signed=True
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)
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return round(scaledVoltage * 156.25e-9, 1)
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# convert to Volts (156.25nV per LSB * 1e-9 for scaling from nV to Volts)
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def tAmbient(self) -> float:
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"""Reading from Ambient Temperature Register in Degrees Celsius"""
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ptrTambient = smbus2.i2c_msg.write(self.addr, _REG_TAMB)
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readTambient = smbus2.i2c_msg.read(self.addr, 2)
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self.i2c.i2c_rdwr(ptrTambient, readTambient)
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scaledTemp = int.from_bytes(
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readTambient.buf[0] + readTambient.buf[1], byteorder="big", signed=True
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)
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return round(scaledTemp * 0.0078125, 1)
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# convert to degrees Celsius (1/32 for scaling * 1/4 for 2 bit shift)
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@property
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def manID(self) -> bytes:
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"""Sensor manufacturer ID"""
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ptrManID = smbus2.i2c_msg.write(self.addr, _REG_M_ID)
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readManID = smbus2.i2c_msg.read(self.addr, 2)
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self.i2c.i2c_rdwr(ptrManID, readManID)
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return readManID.buf[0] + readManID.buf[1]
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@property
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def devID(self) -> bytes:
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"""Sensor device ID"""
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ptrDevID = smbus2.i2c_msg.write(self.addr, _REG_D_ID)
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readDevID = smbus2.i2c_msg.read(self.addr, 2)
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self.i2c.i2c_rdwr(ptrDevID, readDevID)
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return readDevID.buf[0] + readDevID.buf[1]
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