Category: Altera

User-Customizable ARM-Based SoC FPGAs for Next-Generation Embedded Systems

White paper

"This white paper discusses Altera's programmable system-on-chip (SoC) approach to ARM-based embedded system implementation. The single-chip approach can be of particular value to embedded systems developers facing stringent time-to-market, cost, performance, design reuse, and longevity requirements.

Introduction

Today's embedded system developers face unprecedented challenges in their efforts to rapidly deliver competitive products to market. Until recently, most system implementation options have been limited to software-intensive, power-hungry multichip systems or costly SoC ASICs. However, market forces and resource constraints are compounding to make these approaches less viable for many design teams. For ARM-based embedded systems, though, advances in FPGA technology, intellectual property (IP), and design tools have witnessed the emergence of user-customizable SoC FPGAs. These devices not only overcome the shortcomings of traditional approaches, but offer unique and significant advantages for embedded"

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Category: STM32F

AN4044 Using floating-point unit (FPU) with STM32F405/07xx and STM32F415/417xx microcontrollers

"Introduction

This application note explains how to use floating-point units (FPU) with STM32F405/07xx and STM32F415/417xx microcontrollers and provides a short overview of:

• Floating-point arithmetic
• STM32F405/07xx and STM32F415/417xx family floating-point unit

An application example is given at the end of this application note."

"Julia set

The target is to compute a simple mathematical fractal: the Julia set.

The generation algorithm for such a mathematical object is quite simple: for each point of the complex plan, we are evaluating the divergence speed of a define sequence.

The Julia set equation for the sequence is:

z_n+1 = z_n² + c

...

Conclusion

The FPU makes this very simple algorithm 11.5 to 17 times faster. No code modification has been done, just activating the FPU in the compiler options.

The STM32F4 FPU allows very fast mathematical computation on float and is a key benefit for many applications needing floating-point mathematical handling such as loop control, audio processing or audio decoding or digital filtering.

It makes the development faster and safer, from high level design tools to software generation."

PDF document link

Category: USB

Which version of USB is right for your application?

Part 1 - web page link

"The Universal Serial Bus (USB) peripheral interface has become ubiquitous across all personal computing platforms as well as many industrial and infrastructure platforms. However, at the same time, the version of the specification that is right for a given application—USB 1.0, USB 1.1, USB 2.0, On-the-Go (OTG), WirelessUSB (WUSB)—can lead to confusion. "

Part 2 - web page link

Part3 - web page link

"The second most significant development (the release of the USB 3.0 specification being the most significant) in the USB market since my original articles is the use of the USB connector for charging battery-powered portable-consumer products. When first released, the USB specification did not really take into account the potential desire to charge batteries with VBUS that is defined as 5V and 500 mA for a host port or a self-powered hub port."

"How does Thunderbolt™ technology affect USB?

Obviously, Thunderbolt™ technology (TBT) is very new at this time, and how this plays out over time is still to be determined. If you are unfamiliar with TBT, I recommend going to the Intel Thunderbolt Community for more details. The basic concept is to take DisplayPort (DP) and PCI-Express (PCIe) in the host system, aggregate them, and send out the combined transmission over a single cable, Figure 1."

Category: Web Projects

Citizen Sensor

"Citizen Sensor is a DIY and open-source hardware and software initiative to encourage personal and community pollution monitoring. Development has been done in both mobile and stationary forms and has been used in educational, research, and artistic applications around the world."

Web page link

Category: I2C

Optically isolating an I2C interface: Beware of nonlinear propagation delays

"There are many applications requiring ground isolation or logic-level translation between devices where the simple I2C protocol is very useful. The small number of wires (two) minimizes the required number of isolators and keeps down the cost of the isolated systems, although each direction of the wire has generally required its own isolator.

Systems in which the bus can be isolated such that only slave devices exist on one side of the isolation barrier do not need bidirectional isolation of the SCL line. More specifically, a bus containing only I2C slaves that do not need to implement clock stretching (in order to slow down the bus to the speed that they can use) does not need bidirectional isolation of the SCL line. Simplified isolators, with one bidirectional path (for SDA) and one unidirectional path (for SCL), may be used in such systems (see Figure 1)"

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Category: ARM

Efficient C Code for ARM Devices

PDF document link

"Originally published: ARM Technology Conference 2010, Santa Clara CA, Session ATC-152

Our industry moves incredibly quickly. The hot topic last year is very rarely so important this year – either we will have solved it or some other issue will have risen to even greater prominence. The issue of efficiency, however, has been a relatively constant theme through my time in the industry, now some 24 years but efficiency has had many faces over that time.

In the early days, I can recall developing local area networking software on small 8-bit microcontrollers where RAM was the scarce resource. We worked long and hard to come up with cleverer and cleverer ways of storing, compressing, reusing and encoding our necessary data structures to make them fit."

Web page link

Category: ARM

Introducing the ARM Cortex-M0+ processor: The Ultimate in Low Power

"Web page link"The ARM Cortex-M0+ processor is the most energy efficient ARM processor available. It builds on the Cortex-M0 processor, retaining full instruction set and tool compatibility, while further reducing energy consumption and increasing performance. Along with the Cortex-M0 processor, the exceptionally small silicon area, low power and minimal code footprint of these processors enable developers to achieve 32-bit performance at an 8-bit price point, bypassing the step to 16-bit devices. Read this paper to learn more."

Web page link

Category: Sensor Networks

Science Tricorder Mark 2

"To introduce you to the Tricorder project, I'd like to begin with a story from the development of the very first Tricorder that I built. The first educational discoveries with the Tricorder came only moments after completing it, and walking about the workshop to "see what can't be seen". Upon holding the Tricorder near a power adapter plugged into the wall, you could see the oscillating magnetic fields on the magnetometer visualization. There they were, slowly bouncing back and forth, right in front of you. My father had taught me how transformers work from a young age — two coils are wound together, each having a different number of windings, where an oscillating magnetic field from one coil would induce a voltage in the other coil proportional to the ratio of their number of windings. I know how transformers work — I have known since he explained it to me, I know the equation that determines the output given the input and a certain number of windings — but I had never seen it work until then, until I had this Tricorder in my hands. It grounded my knowledge of the electromagnetic phenomena at work in transformers with something that I could easily watch and see, and use to see inside /any/ transformer, right in front of me. And from that moment on, it seemed like much of the mystery of how they worked I now understood — I could think about what was going on inside them easier and more naturally, now that I had visually grounded the science going on inside. This is why I built the Tricorder."

Web page link