Online DSP primer – Circles, Sines, and Signals

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Seeing Circles, Sines, And Signals is an interactive “Compact Primer On Digital Signal Processing” by Jack Schaedler. It’s getting a lot of positive comments. Jack says:

My goal is to explain the Discrete Fourier Transform using a miniature curriculum which leverages your ability to learn concepts and absorb information visually instead of linguistically. My hope is that these glyphs become slightly more comprehensible and slightly less intimidating after reading the subsequent 30 or so pages.

Articles like this seem popular on SynthTech, and this is a very-well-done intro, so have at it!


Blogroll pruned

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I’ve just pruned the blogroll to eliminate the dead, those gone commercial, those who’s attention has wandered. Oh and added Palm Sounds, which is mostly about the mobile sound scene but useful nonetheless.

BeagleBone Black board includes 1GHz ARM7, 512MB RAM, Linux

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(NB This is not an ad, it’s in lieu of a review, see Ars. Don’t own one … just a heads up. Considering the established community around the RasPi, this product will probably *never* be that big.)

Story at Ars Technica.

Short version

* 1GHz Sitara AM335x ARM Cortex-A8 processor
* more than 30 “capes,” or plug-in boards compatible
* 512MB of DDR3L memory
* 3D graphics accelerator
* MicroHDMI slot, USB, 10/100 Ethernet
* 65 digital I/O connectors, seven analog ones, four serial ports, and eight pulse-width modulators. (Two 46-pin headers)
* 2GB of on-board storage that’s pre-installed with Ångström Linux and BoneScript, “a node.js-based language”.
* comes with a power supply and network cable

BeagleBone Black page
CircuitCo wiki page
Newark order page

Raspberry Pi Review & Setup Guide

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There’s been a lot of attention around the $35 Raspberry Pi computer board. This is the first how-to review I’ve seen. When I find more, I’ll add it below.

Raspberry Pi Review & Initial How-To Setup Guide – TechSpot Reviews.

Update Aug. 1 2012: Android 4.0 is being ported to the Pi.
Update Aug. 3 2012: Adafruit has released a Linux distro for the Pi.

Our distro is based on “Wheezy” but comes with hardware SPI, I2C, one wire, and WiFi support for our wifi adapters. It also has some things to make overall hacking easier such sshd on startup (with key generation on first boot) and Bonjour….

Update Sep. 4, 2012: Yes, es muss sein: the Raspberry Pi Synthesizer Blog (hardware buffs check out The Minterface) … PLUS … Create Digital Music’s article
Raspberry Pi, Your Next $25 Computer Synth? First Hacks Appearing has a lot more links to explore, AND a Pi Synth video!!

Update Nov. 6, 2012: RISC OS has been ported to the RPi. While old (1987) it’s far simpler and smaller (the cooperative multitasking core system fits inside 6MB) and has been updated by volunteers. It’s written for the BBC Micro, so there are tons of programs available (including BASIC). Download free ZIP here… or it can be bought pre-loaded on an SD card. (Related RPi forum post)

Update Mar. 1, 2013: 10 Raspberry Pi creations that show how amazing the tiny PC can be.
The Raspberry Pi: One year since launch, one million sold.
A dozen things to do with a Raspberry Pi.
HTG Guide to getting started with RasPi.

Update Mar. 18, 2013: Slashdot RasPi review and comments. Comments includes optional sources, difficulties, and much more.

Update Apr. 2, 2013: Here’s an example of an automated MIDI and light controller project: RasPi sends MIDI data to the TiMidity file  sequencer and to GPIO-controlled Xmas lights: Raspberry Pi Lights: how to sync Christmas lights to midi audio.
Too complex? Here’s video of a setup that plays MIDI without an operating system. Yes: that means this RPi is generating the sound as well. Author-shared software.
Here’s Silicon Stuff‘s simple hardware/settings needed to get MIDI into and out of the RPi’s UART. SS also points us to a ttymidi program that “allows external serial devices to interface with ALSA MIDI applications.” Oops! no excuses now!

Update Apr. 8, 2013: Computer Vision blog has added a bunch of posts about  using Linux to configure the Raspi lately. E.g. moving user Home directory off SD to a hard drive.

Update May 21, 2013: A $35 RasPi media center.

(Original posted- May 6 2012)

10 Ways to Destroy an Arduino

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10 Ways to Destroy an Arduino is a very useful post about how to avoid smoking your circuit board with I/O mistakes. Complete with scary illustrations. (It can happen to anyone, including people with lots of experience!)

Quick Links:

555 timer chip designer dies

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Retro Thing has published a short obit called
RIP: Hans Camenzind, Inventor Of The 555 Timer. The 555 timer IC (along with the 556 dual-circuit and 558 quad-circuit packages) has been widely used in inexpensive electronics since it was introduced in 1972 by Signetics.

MAKE has an article on the widely-useful timer by Charles Platt, who points out an interview at the Semiconductor Museum. Things were different in Silicon Valley back then:

There are no patents on the 555. Signetics did not want to apply for a patent. You see, the situation with patents in Silicon Valley in 1970 was entirely different than it is now. Everybody was stealing from everybody else. I designed the 555 Signetics produced it, and six months, or before a year later, National had it, Fairchild had it, and nobody paid any attention to patents. The people at Signetics told me they didn’t want to apply for a patent, because what would happen if they tried to enforce that patent, is the people from Fairchild would come back with a Manhattan-sized telephone book and say “These are our patents, now let’s see what you’re violating”.

Before the 555, many designers had to choose custom-made crystals as a basis for circuit timing. The crystals – which were often “overkill” as the circuits didn’t require that kind of accuracy –  were expensive and could take a long time to find and acquire. The 555 is also very versatile, capable of playing roles in many different kinds of circuits, like: pulse detection, bouncefree switching, touch switching, frequency division, capacitance measuring, pulse-width modulation, lamp flashing, pulse generation, logic clocking, tone generation, etc.

Many millions of 555s are still made each year. Many simple circuits using the 555 can be found on the web. For one example look at these at electroniq.net.
This short video demos a sound generator (with more 555 videos in the sidebar).

Kamenzind’s book Designing Analog Chips can be found online in PDF form here.

Beavis Board open-sourced

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Getting started with DIY electronics?!

Tom Whitwell over at Music Thing (!!) reported (back in May)  that the Beavis Board has been open-sourced.

It’s an “effects pedal DIY kit designed to streamline the creation and testing of pedal-style effects.” You may have seen some of them sell for serious dollarage. Or just want to roll yer own – it’s the Yankee way.

via  Music Thing Modular.

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