Monthly Archives: September 2016

Does the Raspberry Pi 3 Run Hotter than the Raspberry Pi 2?

Several people are now eagerly using and testing the new SBC or single board computer from the Raspberry Pi Foundation, the Raspberry Pi Model 3, or RBPi3. Although the overall response has been of enthusiastic welcome, there are some notes of concern as to the new board running rather warm under load. Michael Larabel has run some tests to compare and show just how warm the RBPi3 can get when compared to what the RBPi2 does. Finally, we suggest some remedies for cooling down the RBPi3.

Michael has used the Phoronix Test Suite while monitoring the SoC temperature on both, the RBPi3 and RBPi2, when running the same benchmarks in the same manner for both. One important point to note is the RBPi2 was running inside its case, while the RBPi3 ran completely exposed.

The average temperature of the SoC on the RBPi3 under load was 61∞C, peaking at 82∞C. Under the same conditions, the RBPi2 (within its case), recorded an average temperature of 48.9∞C, peaking at 59∞C. That means the RBPi3 under load, operating in open air, was peaking at more than 20∞C, over its predecessor. That also means if you are planning to put the RBPi3 inside a case when operating, it might make matters worse.

Therefore, if you are planning to stress your RBPi3 routinely, you might consider the following options to keep the RBPi3 temperature down.

Wait for the Linux 4.6 kernel

According to Eric Anholt from Broadcom, the VC4 DRM driver is undergoing an update to get into the Linux 4.6 kernel merge window. This will include a significant 3D improvement in performance and a fix to the HDMI hotplug detection for the RBPi2 and RBPi3. The improvement in performance comes from the RBPi kernel DRM driver pairing with the user-space driver of the VC4 Gallium3D.

Better performance is mainly due to the pipelining, binning and rendering jobs from using xllperf or GLAMOR over OpenGL, which boosts the performance by over 20-30%. The hardware is capable of running separate threads simultaneously for binning and rendering, while OpenGl waits for them to complete before it submits the next job.

Wait for the 64-bit Raspbian

Michael has done some tests to show that there is a conclusive evidence of performance difference between using 64-bit software on supported hardware over a 32-bit operating system. Since the new RBPi3 is a 64-bit system at hardware level, the results should apply to this SBC as well.

For the test, Michael has used an Intel UX301LAA ultrabook with 8GB of RAM and 128GB SanDisk SSD. The operating system was Ubuntu 16.04 daily ISO build, in 64-bit and 32-bits version.

The average power used by the 64-bit system was 30.1W compared to 31.9W by the 32-bit system. Lowest power consumption with 64-bit build was 8.5W compared to 9.4W. The peak power consumed by the 32-bit system was higher at 54.3W compared to 49.7W by the 64-bit system.

Use a Heat Sink to Cool the RBPi3 immediately

For immediate relief, you can use the passive heatsink available that fits the RBPi2 as well as the RBPi3. At $5 from Amazon, this solution is cost-effective in addition to being immediately available. Moreover, the heatsink will drop the temperature of the SoC by almost half.

Cayenne on a Raspberry Pi

If you are building projects for IoT or the Internet of Things, a single board computer such as the Raspberry Pi, also known as the RBPi, can be a great asset. Moreover, with Cayenne installed on the RBPi, you have a drag-n-drop IoT project builder that the developers of the Cayenne software, myDevices, claims is the first in the world.

Therefore, now it is easy to connect your RBPi to a mobile or online dashboard. On the other side, you have a breadboard ready to connect relays, lights, and motion sensors. Of course, you have always had the freedom to write an application, read multiple pages of documentation, and take time to learn new programming languages, write pages of code, and then debug them to make it all work together. Alternatively, you can reduce the time you spend preparing for your project, because Cayenne helps to get your project up and running in a fraction of the time, and you can build your automation projects in minutes.

With Cayenne, myDevices makes all this possible, because they created Cayenne for makers and developers eager to build and prototype amazing IoT projects with their RBPi, as quickly as possible. Users get a free Cayenne account, which allows them to create unlimited number of projects. There is also a full-fledged IoT maker support capability that allows remote control of sensors, actuators, motors, and GPIO boards.

On the free account, you can also store unlimited amount of data that the hardware components collect including triggers and alerts, providing all the tools necessary for automation. That allows you to set up custom dashboards and threshold alerts capable of highlighting your projects with fully customizable drag-n-drop widgets.

According to myDevices, Cayenne is the first of its kind of builder software that empowers developers to use its drag-n-drop features for creating quick IoT projects and host their connected device projects. Cayenne allows remote control of hardware, displays sensor data, store data, analyze it, and do several other useful things.

In the Cayenne platform, users can find several major components, such as:

The main Application – useful for setting up and controlling IoT projects with drag-n-drop widgets.
The Online Dashboard – set this up through a browser to control your IoT projects.
The Cloud – useful for storing devices, user and sensor data, actions, triggers, and alerts. Additionally, it is also responsible for data processing and analysis.
The Agent – useful for communicating with the server, hardware, and agent for the implementation of outgoing and incoming alerts, triggers, actions, and commands
Whenever you press a button from the online dashboard or the Cayenne app on your mobile, the command travels to the Cayenne Cloud for processing and travelling to your hardware. The same process takes place in the reverse direction as well. Cayenne offers users plenty of features.

You can connect to your IoT through Ethernet, Wi-Fi, or mobile apps. It is possible to discover and setup your RBPi on a network via Ethernet or Wi-Fi. Dashboards are customizable and widgets are drag-n-drop. It is possible to remotely access your RBPi, shut it down, or reboot it. Users can add sensors, actuators, and control extensions connected to the RBPi, and many more.

What if Your Life was Speech Activated?

Although we mostly use speech when interacting with other human beings, interacting with machines using speech is still a distant dream. So far, human-to-machine communication technology has been reserved for science fiction movies. However, many are working to provide groundwork for transforming that vision to reality. For instance, speech recognition software, such as Apple’s Siri for the iPhone 4s, is now quite popular. Yet, there are several challenges to address and many kinks to be smoothened out related to voice authentication and voice-activated commands.

VocalZoom, a startup based in Israel, utilizes military technology and develops proprietary optical sensors to map out vibrations emanating from people when they speak. Their HMC or human-to-machine sensor is coupled to an acoustic microphone voice signal. They translate the output to a machine-readable sound signal. The system delivers a speech-recognition technology that is highly accurate and unparalleled in the market today.

VocalZoom approached the problem of speech recognition in an entirely different way. They came across a military technology commonly used for eavesdropping – a laser microphone to sense vibrations on windows. Designers at VocalZoom surmised that if windows vibrate when people speak, surely other things did too. Their research led them to facial skin vibrations because of voice. They created a special low-cost sensor small enough to measure facial vibrations similar to the way microphones did. Their speech recognition system uses microphones, audio processors and the special sensor.

The special sensor is actually an interferometer to measure distance and velocity. Therefore, it can be used as a microphone for measuring vibrations of audiobe used for 3D imaging, proximity sensing, biometric authentication, tapping detection and accurate heart-rate detection. The multifunction sensor has a very wide dynamic range useful for implementation in many applications, for instance, to measure vibrations in engines, industrial printers, or turbines.

A typical sensor for measuring distance and velocity, such as time-of-flight based sensors, use an emitter and a detector. However, designers at VocalZoom use a laser for both purposes. That means their interferometer is of a super low-cost design that practically has no optical component. However, they had to cope with noise issues and it was necessary to develop noise reduction methods when using the sensor with speech recognition systems.

The noise reduction methods used by VocalZoom often use optical sensors to improve speech recognition. They have reached a stage where in an environment with a lot of background noise, they can reduce the results of the speech recognition or voice authentication to a very low error rate.

In actual practice, the laser is directed at the face of the person talking. It measures vibrations that are in the order of tens and hundreds of nanometers, not usually picked up by normal sensors. As the laser measurements are so precise, other surrounding noise does not interfere with the micro-measurements of the skin, which are then converted into clear audio.

Very soon, you will be able to use the optical laser technology of VocalZoom together with Siri or Google Voice and other voice-recognition applications for a wholly different experience.

Smart Amplifiers to Give More Bass

As our smartphones get smaller and thinner, one of the consequences is the loss of bass or low frequency sounds we are accustomed to hearing naturally. The miniaturization of all components, including the loudspeaker, leads to voice or audio reproduction from the gadget seem unnatural. This is mainly because handset manufacturers have been slow to improve the audio performance, except in high-end handsets, leading to a lack of low-frequency audio.

However, the situation is changing now. A technology called smart amplifier is available to extract the maximum performance from the micro-speaker of a cell phone. Where the coupling between a traditional amplifier and its speaker is unidirectional, a smart amplifier senses the loudspeaker’s operation while playing. It also applies advanced algorithms to drive the loudspeaker to its maximum without hurting your ears.

To discuss the operation of a smart amplifier, it is important to understand that a loudspeaker is a vital component in the audio reproduction chain. If the design of the loudspeaker is not up to the mark, no amount of amplification or audio processing will overcome its shortcomings. However, if you even have a reasonable loudspeaker to start with, a smart amplifier can turbo charge it and push it to its limits.

Speakers contain a frame, voice coil, magnet, and diaphragm. Electrical current from an amplifier coursing through the voice coil magnetizes it, making it react with and move against the fixed magnet of the speaker. The movement causes the membrane or diaphragm attached to the coil to also move back and forth, and emanate audible sound waves. The movement of the diaphragm is called excursion, and it has its limits – audible distortions can occur when an amplifier exceeds the limits of this excursion – leading to failure in extreme cases.

Traditionally, amplifiers have used simple equalization networks at their outputs to limit this excursion. Because there can be large varieties of speakers, and different operating conditions including extreme audio signals, the filters are generally conservative. They actually limit the capability of the amplifier to push the speaker to its true limit. Additionally, current through the voice coil generates heat to some extent, and this factor limits the extent to which an amplifier can drive the speaker.

With micro-speakers commonly used in smartphones, smart amplifiers use feedback when driving them. A common method with Class-D amplifiers is to add IV or current and voltage sense to the DAC or digital to analog converter that provides a feed-forward solution. With IV-sense, the system receives feedback about the speaker’s voice coil temperature, its loading, and variations from unit to unit. The algorithm in the system uses this information to extract the maximum SPL or sound pressure level from the speaker without damaging it.

However, before a smart amplifier can drive a loudspeaker safely, a few steps are necessary. These include thermal characterization, excursion characterization, and SPL measurements for the speaker. Usually, data plots are necessary of excursions versus frequency and safe operating area limits.

Smart amplifiers such as the TAS2555 from Texas Instruments have a DSP or digital signal processor integrated. That reduces the time required for software development tremendously.

Trombe Wall to Heat and Cool Buildings Using Renewable Energy

Researchers at Lund University, Sweden have devised a technique for using an adaptation of the nineteenth century Trombe wall for heating and cooling modern buildings. The modified structure is capable of reducing carbon emissions associated with the heating and cooling processes, as well. Residents of Saint Catherine in Egypt are trying out the invention.

Trombe wall basics

A Trombe wall was a popular method used in the nineteenth century to keep buildings cool during the day and warm at night. The construction was simple, consisting of a very thick wall painted black on the outside surface and with a glass pane in front of it. The black surface, being a good absorber allowed the wall to absorb heat from the sun’s rays falling on it. The glass surface, being a bad radiator trapped the heat for some time. However, as the temperature dropped during the night, the heat was released slowly, keeping the building warm for several hours. Homes and buildings in the northern hemisphere had a south facing wall, while those in the southern hemisphere, a north-facing one.

An additional advantage of this structure is that the glass sheet causes the release of infrared rays. The warmth produced by these rays is more agreeable than the heat generated by traditional convection methods.

Marwa Dabaieh, an architectural scientist at the university has tried out the modern version of the Trombe wall in Egypt where 94% of the energy used is derived from fossil fuels. She explains that the innovation could help reduce dependence on electricity and cut down carbon emissions.

Cost effective production

The researchers have taken care to retain the basic construction methods. The old but popular passive technique has been employed, meaning there are no mechanical parts involved. This makes for an economical operation. The materials that are used are easily available. Wood and locally quarried stone are used for the basic construction, while wool is used for insulation. The glass used is produced locally, too.

Ventilation system

The modified version relies solely on naturally available solar energy and prevailing wind currents in the region. This makes for a very cost effective design structure.

Dabaieh reveals that the new design employs the concept of ventilation to utilize the air streams to generate cooling techniques. This is a major improvement upon the older version of the Trombe wall, which often caused over heating inside the building. The researchers are continually adjusting the vent structures and positions to make the temperature more endurable. This eliminates the need for air conditioning in the hot summer months.

Roping in the locals

Dabaieh reveals that the project has engaged local residents in the construction and installation process. This will help cut down costs further and provide employment opportunities for young people. Since many homeowners in St Catherine who have put up the Trombe wall, have expressed their satisfaction about the structure, several other residents are keen on installing it.

The adapted Trombe wall is a cheap and efficient system that could serve to meet the challenges posed by rising energy requirements worldwide.