If you want to keep something at a certain temperature, say a block of aluminum, you’ll need a thermocouple and some sort of heating element. While you could turn a heater on and off abruptly in a sequence appropriately known as “bang-bang,” a more refined method can be used called PID, or proportional-integral-derivative control. This takes into account how much the temperature is outside of a threshold, and also how it’s changing over time. [via]
Hi guys, in one of our previous tutorials, we built a real-time clock with temperature monitor using the DS3231 and the 16×2 LCD display shield. Today, we will build an upgrade to that project by replacing the 16×2 LCD display with an ST7735 based 1.8″ colored TFT display.
Apart from changing the display, we will also upgrade the features of the project by displaying the highest and lowest temperature that has been measured over time. This feature could be useful in scenarios where there is a need to measure the maximum and minimum temperature experienced in a place over a particular time range.
This tutorial is based on the ability and features of the DS3231 RTC module. The DS3231 is a low power RTC chip, it has the ability to keep time with incredible accuracy such that even after power has been disconnected from your project, it can still run for years on a connected coin cell battery. Asides from its ability to accurately keep time, this module also comes with an accurate temperature sensor which will be used to obtain temperature readings during this tutorial.
Arduino Real Time Clock with Temperature Monitor – [Link]
The HDC2010 is an integrated humidity and temperature sensor that provides high accuracy measurements with very low power consumption, in an ultra-compact WLCSP (Wafer Level Chip Scale Package). The sensing element of the HDC2010 is placed on the bottom part of the device, which makes the HDC2010 more robust against dirt, dust, and other environmental contaminants. The capacitive-based sensor includes new integrated digital features and a heating element to dissipate condensation and moisture. The HDC2010 digital features include programmable interrupt thresholds to provide alerts/system wakeups without requiring a microcontroller to be continuously monitoring the system. This, combined with programmable sampling intervals, low inherent power consumption, and support for 1.8V supply voltage, make the HDC2010 well suited for battery-operated systems.
Researchers at the University of Warwick in the UK have developed sensors which measure the internal temperature and electrode potential of Lithium batteries. The technology is being developed by the Warwick Manufacturing Group (WMG) as a part of a battery’s normal operation. More intense testings have been done on standard commercially available automotive battery cells.
If a battery overheats it becomes a risk for critical damage to the electrolyte, breaking down to form gases that are both flammable and can cause significant pressure build-up inside the battery. On the other hand, overcharging of the anode can lead to Lithium electroplating, forming a metallic crystalline structure that can cause internal short circuits and fires. So, overcharging and overheating of a Li-ion battery is hugely damaging to the battery along with the user.
The researchers at Warwick developed miniature reference electrodes and Fiber Bragg Gratings (FBG) threaded through a strain protection layer. An outer coat of Fluorinated Ethylene Propylene (FEP) was applied over the fiber, ensuring chemical protection from the corrosive electrolyte. The end result is a sensor which has direct contact with all the key components of the battery. The sensor can withstand electrical, chemical and mechanical stress faced during the normal operation of the battery while still giving accurate temperature and potential readings of the electrodes.
The device includes an in-situ reference electrode coupled with an optical fiber temperature sensor. The researchers are confident that similar techniques can also be developed for use in pouch cells. WMG Associate Professor Dr. Rohit Bhagat said,
This method gave us a novel instrumentation design for use on commercial 18650 cells that minimizes the adverse and previously unavoidable alterations to the cell geometry,
The data from these internal sensors are much more precise than external sensing. This has been shown that with the help of these new sensors, Lithium batteries that are available today could be charged at least five times faster than the current rates of charging.
This could bring huge benefits to areas such as motor racing, gaining crucial benefits from being able to push the performance limits. This new technology also creates massive opportunities for consumers and energy storage providers.
California based company, Integrated Device Technology (IDT) has recently announced their new HS300x family of MEMS high-performance relative humidity (RH) and temperature sensors of dimension 3.0 × 2.41 × 0.8 mm DFN-style 6-pin LGA. Currently, there are four devices in this family—the HS3001, HS3002, HS3003, and HS3004. They are all the same from the view of functionality but differ slightly in terms of the accuracy of their relative humidity and temperature measurements.
The highlighted feature of this new lineup is that they do not require any user calibration. HS300x family of ICs has calibration and compensation logic integrated into the devices. These ICs output their fully corrected data using standard I2C protocols making the measured data from the sensors is rather easy.
As a side note, Relative humidity (RH) is the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at a given temperature. As the entire output consists of only four bytes of data, calculating the corresponding relative humidity in percent and temperature in degrees Celsius is very easy.
Although the HS300x sensors operate as slave devices on the I2C bus (supporting clock frequencies from 100 kHz to 400 kHz), only one HS300x IC can be connected directly to a single I2C bus. To connect multiple sensors to a single I2C bus, an I2C multiplexer/switch has to be used. It would have been easier if IDT had dedicated the unused pin as an optional I2C address input bit, which would allow two HS300x devices to be connected to a single I2C bus.
If you’re interested in testing these ICs prior to incorporating them into a design, SDAH01 or SDAH02 evaluation kit can come handy. Although both kits utilize the HS3001 sensor, the SDAH01 kit outputs the measured data to a PC while the SDAH02 displays the data on an LCD screen.
At this year’s AHR Expo 2018 trade show in Chicago (January 22 – 24, 2018), Sensirion, the expert in environmental and flow sensor solutions, is introducing the SCD30 – a humidity, temperature and carbon dioxide concentration sensor.
CMOSens® Technology for IR detection enables highly accurate carbon dioxide measurement at a competitive price. Along with the NDIR measurement technology for CO2 detection, a best-in-class Sensirion humidity and temperature sensor is also integrated on the same sensor module. Ambient humidity and temperature can be outputted by Sensirion’s algorithm expertise through modeling and compensating of external heat sources without the requirement for any additional components. Thanks to the dual-channel principle for the measurement of carbon dioxide concentration, the sensor compensates for long-term drifts automatically by design. The very small module height allows easy integration into different applications.
Carbon dioxide is a key indicator of indoor air quality. Thanks to new energy standards and better insulation, houses have become increasingly energy efficient, but the air quality can deteriorate rapidly. Active ventilation is needed to maintain a comfortable and healthy indoor environment, and to improve the well-being and productivity of the inhabitants. Sensirion’s SCD30 offers accurate and stable CO2, temperature and humidity monitoring. This enables customers to develop new solutions that increase energy efficiency and simultaneously support well-being. With the new SCD30, Sensirion has expanded its portfolio to include environmental sensor for air quality measurement.
Visit Sensirion at AHR Expo 2018 (Booth 3858) and learn more about the SCD30, Sensirion’s new humidity, temperature and carbon dioxide sensor module.
Data loggers are small, battery-powered devices used to sense and store information in different situations. They include a microprocessor, data storage, one or several sensors and they can record information for a very long period. However, some data loggers do not include sensors, but have ports that allow a sensor to be connected. They are used indoors, outdoors, and underwater for recording precise information about the environment they are in. Some applications may include monitoring light or temperature in crops, filed conditions, water level, and indoor humidity etc. Additionally, the information on these loggers can be accessed remotely or via USB.
In Hackaday a man named Nikos started a project to protect sea turtles through research which consisted of creating a small, cheap, and power efficient temperature logger. Temperature is one of the main factors in sea turtle egg incubation success, because of climate change increasing temperatures may affect this process, so researching and monitoring temperature changes in sea turtle nesting habitats is necessary to mitigate the impact of a changing climate.
The objective of the project is to develop a temperature logger that is accurate, stores records for at least 180 days, samples temperature every 10 minutes, can operate for 180 days with a coin cell battery, is waterproof, costs less that 5 euros and can easily transfer information via computer cable. For research a huge quantity of data is needed which is why many companies use many loggers with a lot of storing capability, but this may result in high costs.
The sensor chosen for the project is the MAX30205 which can achieve a 16-bit resolution at a low consumption and cost. The creator also considered the Silicon Labs’ Si7051 and Texas Instruments’ HDC1080, but the MAX30205 was chosen because it had more details in accuracy over its operating range (which is better for scientific research).
As the temperature sensor gives its reading in 2 bytes then for the 180 days with 10 minutes intervals of reading 414720 bits will be needed, so a 512 Kbit memory was chosen. Taking price into consideration the Adesto’s AT25DN512C that comes in TSSOP-8 package was chosen. An advantage is that this type of package is small enough for the objective and its also available for 4 Mbit versions, so extra memory can be used. Also, the mcu used was the ATMEGA328PB-MN.
The project has not been finished and some improvements have been made and others are planned to be made soon. If you want to follow this project and know how it develops you can found it on its Hackaday official website.
It can detect movement and room conditions and connect over WiFi with a passive IR occupancy sensor, barometer, temperature and humidity sensors, and the Microchip ATSAMW25 module. Pre-flashed with the Arduino bootloader, the RoomSense is easily deployable as a home automation device by developers of all skill levels.
This tiny USB dongle uses a passive IR motion detector, and temperature, humidity and barometric sensors to monitor a room’s conditions and occupancy. The Microchip ATSAMW25 provides a SAMD21 Cortex-M0+ MCU and WiFi connectivity. It integrates easily with cloud IoT platforms such as MyDevices Cayenne.
ARM Cortex-M0+ MCU at 48 MHz
Barometer, humidity and temperature sensors
Passive IR motion detector
Powered over USB
RoomSense Board offers multiple sensors including PIR motion detection – [Link]