QtLedTest – Software to Evaluate OLED Displays

A few days ago we featured the USBPass, an offline password keeper made with very few components. At the end of our write-up we mentioned that [Josh] was already working on another version of his hardware, which involved adding an OLED screen to the platform. To help him pick one he created QtLedTest, a Qt-based tool that simulates different OLED displays and GUI layouts for them. Internally QtLedTest is composed of QLedMatrix (a widget that simulates LED matrices), an SSD1306 OLED controller simulator, a simple graphics drawing library and some functions to draw text on the simulated screen. [Josh] used Fontbuilder together with a program he made in order to convert fonts he had found on the internet to C files. All the source code [Josh] made can be found on Github and should be updated in coming weeks as the final program is a bit slow to render the simulated screens.

Sonar With Python and Conference Call Hardware


[Jason] just tipped us off about his recent experiment, in which he creates a sonar system using standard audio equipment and a custom Python program. In case some of our readers don’t already know it, Sonar is a technique that uses sound propagation to detect objects on or under the surface of the water. It is commonly used in submarines and boats for navigation. [Jason]‘s project uses active sonar, which consists in sending short audio bursts (chirps) and listening for echoes. The longer it takes for the echo to return, the further the object is. Though his proof of concept is not used underwater, that may change if he continues the project.

The audio editing software Audacity was used to make a fast frequency changing chirp, along with PyAudio libraries for the main Python program. Exact time of arrival is detected by correlating the microphone output with the transmitted signal. Given that [Jason] uses audible frequencies, we think that the final result shown in the video embedded below is quite nice.
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A Touch Scroll Wheel via OpenSCAD


Recent experiments with the Arduino CapSense library led [Bryan] around the Internet looking for interesting applications. He hit upon a very cool touch scroll wheel made entirely with PCB traces, but the geometry – three interleaved zig zags is impossible to build in the decidedly ungeometric Eagle PCB package. One thing leads to another and now [Bryan] has a cap touch wheel Eagle part designed entirely in OpenSCAD.

The touch scroll wheel implementation [Bryan] found came from an ST touch controller datasheet and used oddly-shaped patterns to create a capacities sensor. Eagle is terrible for designing anything that isn’t laid out at a 45 degree angle, so he fired up OpenSCAD to draw these triangles. Importing into Eagle was another challenge, but a quick Ruby script to convert a DXF file into a set of coordinates for Eagle’s POLYGON command made everything very easy.

If OpenSCADing touch sensors isn’t your thing, there’s also an Eagle library full of them – something we found last week.

Interview with [Damien George], Creator of the Micro Python project


[Damien George] just created Micro Python (Kickstarter alert!), a lean and fast implementation of the Python scripting language that is optimized to run on a microcontroller. It includes a complete parser, compiler, virtual machine, runtime system, garbage collector and was written from scratch. Micro Python currently supports 32-bit ARM processors like the STM32F405 (168MHz Cortex-M4, 1MB flash, 192KB ram) shown in the picture above and will be open source once the already successful campaign finishes. Running your python program is as simple as copying your file to the platform (detected as a mass storage device) and rebooting it. The official micro python board includes a micro SD card slot, 4 LEDs, a switch, a real-time clock, an accelerometer and has plenty of I/O pins to interface many peripherals. A nice video can be found on the campaign page and an interview with the project creator is embedded after the break.

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Mathematica and Wolfram On The Raspberry Pi


[Stephen Wolfram], possibly the only person on Earth who wants a second element named after him, is giving away Mathematica for the Raspberry Pi.

For those of you unfamiliar with Mathematica, it’s a piece of software that allows you to compute anything. Combined with the educational pedigree of the Raspberry Pi, [Wolfram] and the Pi foundation believe the use of computer-based math will change the way students are taught math.

Besides bringing a free version of Mathematica to the Raspberry Pi, [Wolfram] also announced the Wolfram language. It’s a programming language that keeps most of its libraries – for everything from audio processing, high level math, strings, graphs, networks, and even linguistic data – on the Internet. It sounds absurdly cool, and you can check out a preliminary version of the language over on the official site.

While a free version of Mathematica is awesome, we’re really excited about the new Wolfram language. If it were only an interactive version of Wolfram Alpha, we’d be interested, but the ability to use this tool as a real programming language shows a lot of promise for some interesting applications.

Creating Irregular Board Outlines in KiCad


One of the benefits of plain text file format is that you can go in and edit them by hand. This is part of the KiCad board outline hack which [Clint] wrote about in a recent post. He wanted a unique board outline, which is something that KiCad isn’t necessarily well suited for. His solution was to create the outline as an image, then import it. If you’re wondering what custom shape is called for this type of work we’d like to point you to the (kind of) bottle opening HaDuino. That PCB layout was done on Eagle, which has a bit more leeway with special shapes.

Before getting to the code editing step seen above [Clint] used the built-in feature for KiCad that will turn an image into a component. He exported that code and altered it using a text editor in order to change the layer setting for the shape to that of the board outline. This took him from a plain old image, to a module which can be selected and dropped into the board editing program. It’s a snap to do this sort of thing for the copper layers too if you’re interested in using your mad graphics editing skills to layout an art piece on copper clad.


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