In this article we look at yet another humidity and temperature sensor from TI – this time its the HDC2080 which we will connect up to a Raspberry Pi 3
Lets look at some of the technical information and data from TI
The HDC2080 device is an integrated humidity and temperature sensor that provides high accuracy measurements with very low power consumption in a small DFN package. The capacitive-based sensor includes new integrated digital features and a heating element to dissipate condensation and moisture. The HDC2080 digital features include programmable interrupt thresholds to provide alerts and system wake-ups without requiring a microcontroller to be continuously monitoring the system. Combined with programmable sampling intervals, a low power consumption, and a support for a 1.8-V supply voltage, the HDC2080 is designed for battery-operated systems.
The HDC2080 provides high accuracy measurement capability for a wide range of environmental monitoring and Internet of Things (IoT) applications such as smart thermostats and smart home assistants. For designs where printed-circuit board (PCB) area is critical, a smaller CSP package option is available thru the HDC2010 with complete software compatibility with the HDC2080.
For applications with strict power-budget restrictions, Auto Measurement Mode enables the HDC2080 to automatically initiate temperature and humidity measurements. This feature allows users to configure a microcontroller into deep sleep mode because the HDC2080 is no longer dependent upon the microcontroller to initiate a measurement.
Programable temperature and humidity thresholds in the HDC2080 allow the device to send a hardware interrupt to wake up the microcontroller when necessary. In addition, the power consumption of the HDC2080 is significantly reduced, which helps to minimize self-heating and improve measurement accuracy.
The HDC2080 is factory-calibrated to 0.2°C temperature accuracy and 2% relative humidity accuracy.
Relative humidity range: 0% to 100%
Humidity accuracy: ±2% (typical), ±3% (maximum)
Temperature accuracy: ±0.2°C (typical), ±0.4°C (maximum)
Sleep mode current: 50 nA (typical), 100 nA (maximum)
Average supply current (1 measurement/second)
300 nA: RH% only (11 bit)
550 nA: RH% (11 bit) + temperature (11 bit)
Operating: –40°C to 85°C
Functional: –40°C to 125°C
Supply voltage range: 1.62 V to 3.6 V
|Raspberry Pi 3||Raspberry Pi 3 Model B|
|HDC2080||HDC2080 Temperature and Humidity Low Power Digital I2C Sensor|
|Connecting wire||Free shipping Dupont line 120pcs 20cm male to male + male to female and female to female jumper wire|
|Raspberry Pi 3 Expansion Board||Raspberry Pi 3 Expansion Board|
This is a 3.3v rated sensor even though the pin says Vcc
I used the code from https://github.com/shadowpho/Pi_HDC2080
HDC2000_ADDRESS = (0x40) # 1000000 # Register #2 bytes HDC2000_TEMPERATURE_REGISTER = (0x00) HDC2000_HUMIDITY_REGISTER = (0x02) HDC2000_RESET_REGISTER = (0x0E) HDC2000_CONFIG_REGISTER = (0x0F) HDC2000_MANUFACTURERID_REGISTER = (0xFC) HDC2000_DEVICEID_REGISTER = (0xFE) #Configuration Register Bits HDC2000_RESET_RESET_BIT = (0x80) HDC2000_RESET_HEATER_ENABLE = (0x8) HDC2000_CONFIG_GO = (0x1) I2C_SLAVE=0x0703 import struct, array, time, io, fcntl HDC2000_fw= 0 HDC2000_fr= 0 class Pi_HDC2080: def readManufacturerID(self): s = [HDC2000_MANUFACTURERID_REGISTER] s2 = bytearray( s ) HDC2000_fw.write( s2 ) time.sleep(0.0625) data = HDC2000_fr.read(2) #read 2 byte config data buf = array.array('B', data) return buf * 256 + buf def readDeviceID(self): s = [HDC2000_DEVICEID_REGISTER] s2 = bytearray( s ) HDC2000_fw.write( s2 ) time.sleep(0.0625) data = HDC2000_fr.read(2) #read 2 byte config data buf = array.array('B', data) return buf * 256 + buf def __init__(self, twi=1, addr=HDC2000_ADDRESS ): global HDC2000_fr, HDC2000_fw HDC2000_fr= io.open("/dev/i2c-"+str(twi), "rb", buffering=0) HDC2000_fw= io.open("/dev/i2c-"+str(twi), "wb", buffering=0) a1 = fcntl.ioctl(HDC2000_fr, I2C_SLAVE, HDC2000_ADDRESS) a2 = fcntl.ioctl(HDC2000_fw, I2C_SLAVE, HDC2000_ADDRESS) if (a1 <0 or a2 < 0): exit() #abort time.sleep(0.1) config = HDC2000_RESET_RESET_BIT s = [HDC2000_RESET_REGISTER,config] s2 = bytearray( s ) HDC2000_fw.write( s2 ) time.sleep(0.1) if(self.readManufacturerID() != 0x4954): print("ERROR CRITICAL MANUFACTURE ID NOT MATCH") exit() if(self.readDeviceID() != 0xD007): print("ERROR CRITICAL DEVICE ID NOT MATCH") exit() # public functions def readTemperature(self): s = [HDC2000_CONFIG_REGISTER, HDC2000_CONFIG_GO ] HDC2000_fw.write(bytearray(s)) #GO s = [HDC2000_TEMPERATURE_REGISTER] # temp HDC2000_fw.write(bytearray(s)) time.sleep(0.1) #wait for measure to be done data = HDC2000_fr.read(2) buf = array.array('B', data) # Convert the data temp = (buf) + (buf*256) cTemp = (temp / 65536.0) * 165.0 - 40 return cTemp def readHumidity(self): s = [HDC2000_CONFIG_REGISTER, HDC2000_CONFIG_GO ] HDC2000_fw.write(bytearray(s)) #GO s = [HDC2000_HUMIDITY_REGISTER] #humidity HDC2000_fw.write(bytearray(s)) time.sleep(0.1) data = HDC2000_fr.read(2) #read 2 byte humidity data buf = array.array('B', data) humidity = (buf) + (buf*256) humidity = (humidity / 65536.0) * 100.0 return humidity def readConfigRegister(self): s = [HDC2000_CONFIG_REGISTER] # temp s2 = bytearray( s ) HDC2000_fw.write( s2 ) data = HDC2000_fr.read(1) #read 2 byte config data buf = array.array('B', data) return buf def turnHeaterOn(self): return def turnHeaterOff(self): return def setHumidityResolution(self,resolution): return def setTemperatureResolution(self,resolution): return
And you call it like this
#!/usr/bin/python import sys import Pi_HDC2080 hdc2000 = Pi_HDC2080.Pi_HDC2080() print ("temperature : %3.1f,"humidity : %3.1f " %(hdc2000.readTemperature(), hdc2000.readHumidity()))
>>> %Run testHDC2080.py
temperature : 27.9, humidity : 35.4
>>> %Run testHDC2080.py
temperature : 27.8, humidity : 35.6
>>> %Run testHDC2080.py
temperature : 27.7, humidity : 35.7
A nice little sensor but at just over $8 there are cheaper sensors available which have the same functionality, the library and code may need some work to work more reliably.