Category Archives: Customer Projects

Raspberry Pi Control for Pool Temperature and Motor

Owners of swimming pools often have no idea of the temperature of the water in the pool relative to the surrounding air. They also are unable to control the pump schedules unless they put up a mains timer. However, using a single board computer such as the Raspberry Pi (RBPi) makes it easy to display the temperature on a webpage, while it switches the pump automatically on or off based on a preset schedule.

The pool monitoring system does not need a full version of the RBPi, as the RBPiZW, the Zero W version, will be adequate. For instance, the designer, Matt, designed the pool monitoring system for his summer escapes pool that holds 4100 liters of water. Matt designed the RBPiZW system to measure the water and air temperature and log the measurements to a cloud on the Internet. This allows the system to display temperatures on a web page he is able to access from a mobile phone, while allowing him to switch the pump on or off. The system can also place the pump on an automatic mode to follow a specific schedule.

Pool pumps are usually mains powered and contain a filter. Traditionally, users control this with a mains timer, but that precludes the possibility of switching it on when the solar panel supplies free power. For instance, the user may want to replenish the water at the end of the day after heavy use, and this is not possible without tinkering with the timer unit.

Matt housed his RBPiZW monitoring system in a weatherproof box. It offered room to include a 4-way extension block and has a 10 m mains cable running to it from the house. The box houses the RBPiZW and its 5 V power supply. The sensor wiring enters the box through rubberized slots.

According to Matt, the finished system comprises, apart from the pool and pump, a weather-proof box, a 10 m mains extension cable, an RBPiZW, a 5 V charger, a 4-GB micro SD card, two water-proof temperature sensors (DS18B20) each with 3 m cable, bias resistor for the temperature sensors, an Energenie Socket, and an Energenie Pi-mote as add-on.

The Energenie socket is a remote control socket. Additionally, when combined with the Pi-mote, it allows controlling the socket with Python scripts. Being easy to set up, this combination offered an easy hardware for controlling the pump. Matt had only to plug in the Pi-mote into the GPIO header of the RBPiZW.

The DS18B20 waterproof temperature sensors are single-wire interface and many of them can be connected to the GPIO pins. The waterproof sensors come with all cables attached. Although somewhat more expensive than the regular standard sensors, Matt only needed to solder the three wires from each sensor to the appropriate GPIP pins on the back of the Pi-mote to make them work.

Matt placed one of the sensors in a hedge near the pool for measuring the air temperature, while he dipped the other into the pool water to measure the temperature of the water. Each sensor has a 3 m cable length.

Interfacing the Tilt Hydrometer and Thermometer to the Raspberry Pi

Tilt is a wireless hydrometer and thermometer combination suitable for home brewers that allow instant readout of the specific gravity of your brew. You can see the specific gravity readings on your Apple iPhone, iPad, or Android smartphone. Furthermore, Tilt can talk to your single board computer, the Raspberry Pi (RBPi).

Tilt will talk to most devices sporting the Bluetooth 4.0+ interface. Once you have the data in your device, you can optionally save the data automatically into a cloud using Tilt’s free Google Sheets template. You can also save the data using other third party cloud platforms as well.

For helping home brewers make better beer, the Tilt hydrometer allows automatic checking of its specific gravity and temperature even while it is fermenting. Simply dip the Tilt hydrometer in the beer within your fermenter and leave it inside. Without having to open your fermenter again, you can receive the data on its present status, and this makes brewing simply more consistent and easy to track.

Tilt has a powerful transmitter, allowing it to send data wirelessly even through large thick-walled fermenter. Therefore, you get a better range and reception. With its sensitive sensors such as the improved temperature sensor and accelerometer, you get precise readings. Power consumption is low, which means Tilt does not consume much battery power while operating.

Operating the Tilt could not be simpler, as each unit comes calibrated and a pre-installed battery, ready to go—you only need to download the free app. Now sanitize your Tilt and drop it in your fermenter. You will automatically receive data on your device.

If you have different batches of fermenting beer, use multiple Tilt Hydrometers. You can differentiate those using separate colors for each batch. The app does not read multiple hydrometers of the same color. The Tilt has a range of 0.990 to 1.120, and gives an accuracy of ±0.002. The thermometer has an accuracy of ±0.5°C (±1°F).

If you have an RBPi with a Wi-Fi dongle and Bluetooth 4.0+ or BLE, you can use the Tilt Pi to log your Tilt readings. Tilt Pi is an SD card image, which you can download from the Tilt webpage and use to boot up your RBPi3 or RBPiZW. After downloading the image, simply write it to an 8GB or higher SD card.

On the SD card, Tilt has included a SETUP.html file that helps with the Wi-Fi and cloud logging setup. This file guides you in creating the configuration files that allow connecting to your local Wi-Fi network. You will also receive an email giving a link to your cloud data log. Another link will also point to your Tilt Pi dashboard, from where you can change settings, calibration, and view the data on your local network.

The Tilt Hydrometer does not include the RBPi, so you will have to buy one. The built-in Bluetooth and Wi-Fi wireless technology included in the Tilt Hydrometer offers reliable cloud and local data logging. The setup is streamlined, so as soon as the RBPi boots up with the Tilt Pi SD card, the system begins logging data.

Storm Glass Lamp: Raspberry Pi Simulates a Storm

Several people have used the versatile single board computer, the Raspberry Pi or RBPi, as many types of educational devices. In fact, the original purpose of conceiving the RBPi was to use it as an educational instrument to further computer programming among children in schools. It has been serving this purpose excellently, and has managed to go even farther. For instance, the RBPi inspired someone to make a weather-simulation lamp for recreating the weather at any place in the world.

The RBPi within the Storm Glass lamp uses the API Weather Underground for accessing current and future predicted weather at any place in the world. At first glance, one may be rather skeptic about the project, especially when the current weather can be gleaned simply by looking out of the window. However, perception soon dawns when explained that the project is actually able to predict weather—observing tomorrow’s weather today. Alternately, it is possible to keep track of the weather in a distant location, say, a prospective holiday destination.

The designer created the cap and base for the lamp by 3-D printing them. The glass sitting in between the two actually belongs to that fancy mineral water bottle readily available in the supermarkets, which people casually overlook and are forever unable to justify buying. The base also holds the RBPi, a microphone, a speaker, and other varied components such as a NeoPixel LED Ring and a Speaker Bonnet from Adafruit.

The Storm Glass lamp uses two important arrangements. One of them is the rain maker and the other the cloud generator. The rain maker uses a tiny centrifugal pump working at 5 VDC to pump water via glass tubing into the lid, from where the rain falls. An ultrasonic diffusor/humidifier, also working at 5 VDC, forms the cloud generator. Only the electronics parts of the diffusor, which create the ultrasonic signal, are necessary, and the rest can be discarded. All the equipment goes in together into one spectacular lamp.

By installing Alexa Voice Service within the Storm Glass lamp, and setting it up to use the Weather Underground API to receive data related to weather conditions in a specified place, these conditions are easily recreated within the lamp, functioning as a home automation device.

When taken outdoors, and placed on a nightstand, the Storm Glass can actually recreated he weather conditions outside. It gives a weather forecast for the day by checking the weather periodically online. For instance, if the prediction for the day is rainy, expect some rain to fall within the Storm Glass Lamp. If the predicted says partly cloudy, you will see clouds forming inside, with some sunshine interspersed.

An RBPiZW powers the project, as it needs both Wi-Fi and Bluetooth support. Apart from the Speaker Bonnet, mini water pump, and the ultrasonic diffuser, there is a NeoPixel 12-LED ring, a 2.5 A micro USB power supply, 8 GB micro SD Card, two TIP 120 transistors and two 2K2 resistors. Additionally, you will also need tubing for moving water, lots of hot glue, and the 3-D printed parts to hold all the above together. All the parts operate at 5 VDC, so there is no additional converter, and the RBPIZW controls everything.

Expanding the GPIO on the Raspberry Pi

Although the single board computer the Raspberry Pi or RBPi has nearly 26 GPIO pins in its earlier models and 40 in its latest, there are times when the project demands more of them. In such cases, a GPIO expander is the only solution, and the MCP23S08, a device that Microchip Technology makes provides an easy way to expand the IO pins of a micro-controller using only a 2-wire serial interface.

The MCP23S08 works with the I2C protocol as a slave device, providing 8-bit, general purpose, bi-directional IO expansion for the I2C bus. It supports a 7-bit slave addressing, with the control byte acting as the read/write bit. Of the slave address, the MCP23S08 fixes the four most significant bits to 0100. This leaves the remaining three bits to be defined by the user as the address bits. Therefore, one can connect up to eight MCP23S08 devices on a common I2C bus at any one time.

It is possible to configure individual bits of the 8-bit GPIO port as either input or output. At the same time, it is also possible to enable the internal pull-up resistor on the port pins to interrupt-on-change. A set of configuration and control registers control these operations. Each resistor has its own address and its power-on reset value, as listed on the datasheet of the MCP23S08.

The first register is the IO direction register, and controls the direction of the data IO. On setting a bit in this register, its corresponding pin assumes an input direction, and if the bit is clear, its corresponding pin works like an output.

With the input polarity register, the user can configure the polarity of the corresponding GPIO port bits. When he/she sets a bit on this register, the corresponding GPIO register bit stores the inverted value present on that pin.

Interrupt-on-change control register controls this feature for each pin. When the user sets a bit on this register, the corresponding pin becomes capable of interrupt-on-change. Of course, for enabling this feature, the user must also configure the INTCON and DEFVAL registers as well.

Interrupt control or INTCON register controls the manner in which the associated pin value compares for the interrupt-on-change feature. If the user sets the bit, MCP23S08 compares the corresponding IO pin against the associated bit in the DEFVAL register. If clear, the MCP23008 compares the corresponding IO pin to its previous value.

The default comparison value or DEFVAL register is for configuring the default comparison value. If the user enables a bit in this register, and the associated pin has an opposite value, it will cause an interrupt.

The PI-SPI-DIN series of IO modules has the RBPi reading 2 modules of eight isolated digital inputs for a total of sixteen inputs and controlling four modules of four relay outputs for a total of 16 relays, all using the IO expander chip MCP23S08.

As the RBPi can select only two chip-select lines, each of the PI-SPI-DIN modules has a jumper selection of five chip selects. The two address lines of the MCP23S08 need to be enabled in the setup routine while determining the port pins as inputs or outputs.

Audio HAT for the Raspberry Pi Zero

The Raspberry Pi Zero (RBPiZ) and its successor, the Raspberry Pi Zero Wireless (RBPiZW) are very small single board computers. The Pi Foundation wanted to keep their cost and size to the low side, so they did not include either a 3.5 mm audio jack or any other audio port. Although this may seem like a setback for many users, some of them were went ahead and figured out how to get audio out of the board with a little hacking.

Another reason for not including an audio port is the Broadcom chipset used for the RBPiZ and RBPiZW does not have a true analog output. Instead, there are two pulse width modulated (PWM) pins that spew out digital output at very high speeds. To get audio out of these two PWM output pins, one has to filter the signal to the audio frequency range. This allows one to fake an audio signal by adjusting the duty cycle of the PWM pins.

According to physicists, for simulating any analog frequency from a PWM signal, the PWM frequency should necessarily be at least ten times higher than the highest frequency to be replicated in the analog range. As the audio signals humans can hear range from 20 Hz to 20 KHz, the minimum PWM frequency should ideally be about 200 KHz. However, the PWM output from the two RBPis is 50 MHz, so we can comfortably filter out the audio part while suppressing the higher frequencies.

The schematic of the audio HAT for the RBPis shows that the two stereo audio channels, left and right, are designated as PWM0_OUT and PWM1_OUT. On the PWM0_OUT, R21 and R20 are two resistors acting as a voltage divider to bring down the 3.3 V signal to about 1.1 V peaks. The corresponding voltage divider on the PWM1_OUT is formed of R27 and R26. Therefore, the stereo audio line level can give an output of 1.1 V peak-to-peak.

The RC low-pass filter that prevents the high frequencies from passing through is made up of capacitors C20 and C26, working in conjunction with R21 and R27 respectively. With the values of the components used on the board, the cut-off frequency for this RC low-pass filter is 17865 Hz, which is very close to the upper limit of audio frequencies, or 20 KHz.

That still leaves the DC voltage part of the signal on the lines, and one must remove it to prevent damage to any speakers or headphones subsequently connected to them. This is done by capacitors C48 and C34, which allow only AC part of the signal to pass through, and block all DC voltages.

As the PWM pins are being taken to the outside of the board, one must also protect the RBPi from ElectroStatic Discharge (ESD), which can travel back and destroy the RBPi. This is taken care of by ESD protection diodes.

All the above sounds very good and simple, but on the RBPi, the actual PWM0 signal on pin #40, and the PWM1 signal on pin #45, are not available, as they have not been terminated into exposed pads. To circumvent this problem, the PWM0 signal has to be rerouted through software to GPIO pin #18, and the PWM1 signal to GPIO pin #19.

VNC: Controlling a Raspberry Pi from Anywhere

Sometime you wish you could remotely control your Single Board Computer (SBC), the Raspberry Pi (RBPi). This could be because you have set up your RBPi as a home security system with a camera that you want to monitor remotely, or the RBPi is in control of some appliance that you would like to switch on/off from a remote location. Ordinarily, to access an RBPi from outside your home network, you would need to give it an IP address, and set up your home router accordingly. However, there is another method to bypass all that.

Before you begin, make sure your RBPi has the latest OS installed, and is set up to access your home network. Also, as you will be exposing the RBPi to the Internet, change its default password at the setup process. Once you have done this, you can use VNC Connect to access your SBC from anywhere.

Using VNC, you can easily connect to any computer remotely on the same network. Additionally, VNC Connect allows you to connect to any computer from anywhere using a cloud connection, and this includes the RBPi as well. Once you have set it up, the VNC Viewer app will allow you to access the graphic interface of your RBPi from any other computer or smartphone.

The most recent version of the RBPi operating system, namely PIXEL, comes with VNC Connect already present. Others can install it via the apt-get command. You will need to install both realvnc-vnc-server and realvnc-vnc-viewer. Once you have done that, run the raspi-config and set VNC as enabled. This will allow you to set up VNC Connect.

Use a browser to go to the sign-up page of RealVNC Raspberry Pi. Enter your email address in the sign up box. The on-screen instructions will now guide you to complete setting up your account with a password.

On the screen of your RBPi, you should see a VNC icon, which you can click to open. Now, click on the Status Menu and select Licensing. Here, you can enter your email address and its password you created on the sign-up page. On the next prompt, select Direct and Cloud Connectivity, to make your RBPi accessible online.

Now go to the computer or smartphone from which you would like to control your RBPi, and download the VNC Viewer application therein. Open the application, and enter your email address and its password you created on the sign-up page.

This should make your RBPi pop-up automatically as an option. You can use to open up the connection. It will prompt you for the username and password of your RBPi. By default, this is pi as username and raspberry as password, unless you have changed the password as instructed earlier. It takes only a few seconds to connect to your RBPi.

Now, as long as your RBPi is connected to the Internet, you can log into and access its graphic desktop from anywhere. That means you have complete control of any software on the RBPi, check on the status of any project it is running, or even play the games stored on your private server.

RS485 & Raspberry Pi: Monitoring Power

Commercial data centers, lighting controls, utility rooms for buildings, and others need to keep a tab on their power consumption. The normal way to do this is by using electronic voltage meters and multi-branch current monitoring circuits. Vytas Sinkevicius wants to monitor power consumption using the ubiquitous single board computer, the Raspberry Pi (RBPi) as the main controller and the RS485 interface in a Branch Current Monitor (BCM) system.

The heart of the power monitoring system is an RBPi 3. Other parts the system uses are a Pi-SPi-RS485 Interface, a VP-EC-BCM Interface, a breakout PCB for an 18-Channel Current Sense Transformer, and a few Current Sense Transformers. Vytas will be writing the software in C, using the Geany compiler.

Electrical engineers use two types of current sense transformers for measuring current. The first type has a continuous hollow core, with the wire carrying the current passing through the hollow of the core. This type of current transformer is suitable for new constructions and requires the main power to be turned off for installations. The breaker wire has to be removed and re-connected after the current transformer is attached.

The second type of current transformer has a split hollow core, where one-half of the core may be separated from the other. Split cores are ideal for applications where the power wiring to the breakers cannot be switched off. By separating the top half of the core, the breaker wire can be placed in the hollow of the lower part, and the top half of the core replaced thereafter. Vytas is using a split-core current transformer, model type CR3110-3000, and CR Magnetics manufacture it.

The Pi-SPi-RS485 Interface provides power to the VP-EC-BCM Interface and communicates with the RBPi. As the RBPi and Pi-SPi-RS485 combination uses the Modbus RTU and RS485 protocols, they can be located as far as 4000 feet away from the actual area where power is being monitored.

The Pi-SPi-RS485 is a perfect fit for the RBPi3, as its ports match the GPIO port on the RBPi3. Moreover, as it duplicates the GPIO expansion port on the other sides of the Pi-SPi-RS485 module, additional modules are easy to add. You can fit the module directly on the back on an RBPi3, or use optional mounting hardware to connect and keep them alongside. All RS485 signals are duplicated on terminal blocks on the board, and on the RJ45 connectors as well.

Each RS485 module has its own power input (9-24 VDC) for powering remote transmitters, and its LDO regulator operating from the 5 VDC bus provides the 3.3 VDC. Therefore, this does not load the 3.3 VDC bus of the RBPi. There are on-board LED indicators for indicating the status of power and RS485 signals. Termination resistors can be selectively switched in using jumper settings provided. The module provides power to the VP-EC-BCM Interface over a CAT5e cable via the dual RJ45 connectors.

The VP-EC-BCM Interface made by VP Process Inc. does the actual power monitoring. This is a converter unit for current sense transformer with 36 channels. It has a 3-kVAC isolation between the primary circuits and the Power/RS485 Interface.

Monitor Appliances with Raspberry Pi

We use many appliances to help us around the house and office. However, most of them are not smart enough to inform us when they have finished the chore allotted to them. That means we have to leave whatever we are doing at intervals to check and monitor the state of the appliances. This reduces our efficiency for doing important work requiring long stretches of concentration.

All this can be set right if you have the single board computer, the Raspberry Pi (RBPi) readily available. You can program it to notify on your phone or desktop when appliances begin or end their cycles. That leaves you free to decide whether you leave your work or not to attend to the appliance.

The project is suitable for any model of the RBPi including the RBPi Zero. Actually, it makes use of a sensitive vibration sensor. Simply stick this sensor monitor onto any appliance. Any equipment, however old, generates mechanical vibrations when working. The sensor detects the minor vibrations and if they continue for a specified time, the sensor assumes the appliance is operating.

You can use this project to get notifications from any appliance such as furnaces, fans, garage door openers, dishwashers, clothes washers, and dryers, in fact, anything that vibrates when operating. Your RBPi sends tweets or PushBullet notifications when a device stops or starts vibrating.

This project needs the following parts: any model of the RBPi, a micro SD card, a USB Wi-Fi dongle, an 801s vibration sensor module, and a micro USB power source capable of supplying 1 amp. The power source can be any model of phone or tablet charger. If using an RBPi Zero, you will also need a micro USB adapter for plugging in the Wi-Fi dongle.

For this project, you can use the Raspbian Jessie Lite operating system. Download the image and transfer it onto the micro SD card. The card should have two partitions—a boot partition formatted to FAT32, and an OS partition formatted to the EXT3 file system. If you use Windows or Mac for transferring the image, you will need drivers to create the EXT3 partition.

Create and add a new ssh file in the boot partition. Include the host name and authentication data for the Wi-Fi. This will enable the ssh daemon, and you will be able to log into your RBPi from your desktop or laptop. It will also allow the OS to connect to your home network automatically when booting.

Insert the micro SD card into the RBPi socket, add the Wi-Fi dongle, and plug in the 801s vibration sensor to the RBPi GPIO pins. Make sure the pins of the sensor, the +5 V, GND, and the data pin, are connected to the proper pins on the GPIO. The data line of the sensor should go to GP15. Plug in the power source, turn the power on and you should be able to connect to your RBPi via ssh.

You will need some additional files and libraries to make this project work. Get them from here. To enable the proper notification time, set the local time zone on the RBPi.

How to Host XBee Sensors with the Raspberry Pi

Hosting sensors on the Raspberry Pi (RBPi) is so simple because the GPIO pins are all available. As most sensors need very little supporting components, hosting multiple sensors on your RBPi is possible. For instance, RBPi can simultaneously host multiple sensors for temperature, pressure, humidity, and other parameters for sampling atmospheric conditions from a weather station.

However, the RBPi does not support digitals signals on its GPIO pins. This is one reason the RBPi is so inexpensive. For accessing digital signals, the RBPi would need a digital to analog converter, preferably a 12-bit device with 4 channels.

Websites such as SparkFun and Adafruit carry a host of sensors and provide a huge amount of information about the products. Google also provides examples of using analog sensors with the RBPi. The restrictions of using only analog sensors and the 3.3 V maximum supply voltage makes the RBPi less versatile than its competitors such as the Arduino. In addition, on the RBPi you must run Python scripts as root, which makes it somewhat more difficult to do than doing so with the Arduino.

Other than connecting sensors directly to your RBPi, you can also consider using the RBPi as an aggregator node by using an XBee to connect to XBee-hosted sensors or Arduino-hosted sensors.

More specifically, you connect the remote sensor with the RBPi using XBee modules. For this, you will need to create a node first. Start with connecting the serial interface, which is a part of the GPIO header on the RBPi, to the serial interface on the XBee. Do not power on your RBPi or the sensor node, until after you have completed and verified all the hardware connections.

You will need an XBee breadboard adaptor and a breadboard. Plug in the adaptor on the breadboard. Now wire the 3.3 V and GND from the RBPi GPIO to the pins on your XBee adaptor. In case you are using the XBee Explorer Regulator from SparkFun, you may connect to the 5 V power line, as the XBee Explorer has an onboard regulator. The serial interface pins on the SparkFun board has the pins arranged in a header on the side of the board. This board also has the onboard regulator to protect the XBee, and you can connect the Explorer to the 5 V pin instead of the 3.3 V pin.

It is much easier to use connectors instead of wires. Therefore, consider soldering breadboard headers to the XBee adaptor and connect to the serial I/O header.

Next, connect the TXD pin of the GPIO on the RBPi to the DIN pin on the XBee Explorer. The RXD pin of the GPIO on the RBPi goes to the DOUT pin on the XBee Explorer. If using the SparkFun adapter, make sure you are connecting to the right pins—check the documentation for the same. Now take the coordinator XBee module and insert it into the XBee.

Before writing your own scripts, you need to download the special library from XBee. This provides a special Python module that encapsulates the XBee protocols and frame-handling mechanisms.

Name Badge with the Raspberry Pi

For people who interact a lot with others, it helps to build relationships if there is a small gizmo available as a handout. Apart from being a conversation starter, this could also be an advertiser for that upcoming project or story. Most people relish being handed a freebie, and a programmable one-off gadget is one of the best.

These were the exact thoughts running through Rob Reilly’s mind when he got a tiny color LCD for Christmas. He conceived the idea of a programmable name badge, as that would certainly grab eyeballs. Being configurable, the message could change to a logo, or graphics as necessary, maybe even through sensor inputs. When you have an idea to sell, having a self-made project considerably adds to your credibility. What Rob Reilly did with an Arduino Pro Mini, Josh King has accomplished with a Raspberry Pi (RBPi) Zero. He calls it the PiE-Ink Name Badge.

For the necessary parts of the name badge project Josh starts with the RBPi Zero, the PaPiRus 2-inch e-ink HAT, an Arduino Powerboost 1000c, and a Li-Po battery. He puts the parts together using some magnets and adhesive putty.

After soldering the header pins to the RBPi Zero, Josh attached the Powerboost, which is a useful power supply. It has a built-in load-sharing battery charger that allows the project to run even when the batteries are charging. Any 3.7 V Li-Po battery can power this DC-DC converter board, which transforms the battery output to 5.2 VDC for powering the RBPi.

At this point, Josh attaches the PaPiRus HAT to the RBPi Zero, securing all the boards with putty, ensuring a snug fit. A mini slide switch in series with the power supply wires completes the assembly and allows on-off functionality.

Josh has Raspbian already pre-installed on the SD card, so he follows it up with the setup for the PaPiRus. He needs to download all the libraries in place for the RBPi Zero to recognize the 2-inch screen. To fit into the e-ink screen, Josh had to scale all images down to 200×96 pixels.

The PaPiRus is an RBPi HAT compliant design with an interchangeable screen size—you can use a 1.44”, a 2.0”, or a 2.7” e-ink display. It has 32 Mb Flash memory with a battery backed RTC, and the onboard EEPROM allows it to be plug and play with the RBPi. To facilitate projects, there is an onboard thermal watchdog, a temperature sensor, and a GPIO breakout connector with solder pads. There are four optional slim line switches on the top, and an optional reset pin header to allow the HAT wake on alarm from the RTC. PaPiRus is suitable for powering from 3.3 or 5 V power supplies, and compatible with RBPi, Arduino, Beaglebones, and many more boards that are similar.

PaPiRus uses the ePaper technology, mimicking the appearance of ink on paper. This technology is different from LCDs, as it reflects light just as ordinary paper does. Moreover, similar to ordinary paper, the ePaper display can hold text and images indefinitely, even without battery power being present.

As the display does not require any power to retain the image, the entire electronics could go to sleep for days together before the image starts to fade slowly.