mirror of
https://github.com/supleed2/ELEC60013-ES-CW1.git
synced 2024-09-19 20:06:17 +00:00
Aadi Desai
540c3e44ef
Byte values in int form need to be converted to bytes before concatenation Active flag buffer needs to be converted to int before comparison with int literal
123 lines
4.7 KiB
Python
123 lines
4.7 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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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 Tobj - 273.15
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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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