Blog posts

Sturdy Pots on Breadboards

Submitted by paul on Fri, 2015-08-14 19:36

Often I throw together a quick demo for the bi-weekly DorkbotPDX meetup, usually involving one or more pots to adjust parameters.  Finally, I've come up with a pretty good way to put pots on solderless breadboards.

Click "Read more" for details and the shared PCB....

Teensy Audio Library Gets S/PDIF Support

Submitted by paul on Mon, 2015-06-08 07:21

Thanks to the amazing effort of Frank Boesing, the Teensy Audio Library now has native S/PDIF output.

Using a $1 TOSLINK connector, or just a red LED, you can get optical S/PDIF digital audio output.

Optical output is useful for projects where Teensy connects to grounded equipment.  There are lots of ways to simply play sounds, but the Teensy Audio Library gives you Arduino-sketch controlled synthesis, mixing, effects & filters, analysis and much more.  Sketch controlled sound is most useful when you connect more hardware to Teensy & use other Arduino libraries for inputs.  But often that other hardware comes with ground connections that cause audio-corrupting ground loop problems with analog audio, like the DAC pin or the audio shield.  Optical S/PDIF give you perfect digital audio output for those projects!

Click "Read more" for much more detail about the S/PDIF development....

Ten Watt RGB LEDs

Submitted by paul on Mon, 2015-06-01 03:25

Spent a good portion of the weekend fiddling with insanely bright 10 watt RGB LEDs.

Trying to make very low-cost DMX protocol control, of course for a Burning Man project that's planning to use 150 of them!

Control Voltage (CV) to Analog Input Pin

Submitted by paul on Wed, 2015-04-22 05:54

Often I've been asked how to get synth control voltage (CV) into an analog input pin.  Teensy 3.1 has 13 bits effective analog resolution, good enough for many CV applications, but the stable internal reference is only 1.2V with analogReference(INTERNAL).

This simple circuit converts the -5V to +5V CV signal range to the 0 to 1.2V ADC input range.

Edit: here's a discussion about this circuit's details and limitations (fancy opamp-based circuits can be better).

For Sale

Submitted by Howme on Sat, 2015-04-11 20:36

I have 4 12v strands of 50 WS2801s for sale (200 Adressible RGB LEDs total). If someone is willing to swap a $100 bill for them, they're yours.

Power Playground Project

Submitted by spacewrench on Sat, 2015-02-14 09:54


Power Playground

Here's a few pictures of my latest project: "Power Playground."  It's a PMOS/NMOS H-Bridge with FETs that can handle 3 amps or so, plus a SPI current sensor, some switches & a rotary encoder (not stuffed yet), and a 7-segment display, all controlled by a Teensy-3.1 running FreeRTOS.

Art and tech events this week!

Submitted by skinny on Wed, 2015-02-04 16:54

We are extremely lucky this week to have THREE art/tech events happening here in Portland featuring artwork from some of our favorite creative coders. Have fun and support your art/tech community by coming out for these events! The first two are part of First Thursday and you can easily walk between them.

Dungeon Hacker at DIODE Gallery Thursday Feb 5 6PM-9PM 514 NW Couch Featuring Dan Cohen, Ryan Johnson, Andy Lunday, and Gabe Shaughnessy http://www.augmentedart.com/hack-the-dungeon/

Electric Fields by Jeremy Rotsztain at UPFOR Gallery Thursday Feb 5 6PM-8PM - 929 NW Flanders http://www.upforgallery.com/future/


ByteMe 4.0 at AFRU Gallery Friday Feb 6 6PM-11PM - 534 SE Oak St. Featuring Church of Robotron, Libby White, John Brown, Ben Purdy, and more! http://www.afrugallery.com/event/byte-me-4-0/

A few of us worked on the Church of Robotron install for ByteMe, so here's a far too large flier for it!

VS1053 Troubleshooting

Submitted by paul on Fri, 2014-12-12 10:30

Last night, I looked into why Adafruit's VS1053 only works with Teensy 3.1 at 24 MHz, but not 48, 72 or 96 MHz.

Turns out, the library depends SD.begin() to reconfiguring SPI.  It also runs data transfer code from both main program & interrupt context (causing havoc if the interrupt occurs at the wrong moment).  Pretty amazing it's worked on AVR for so long, but apparently it does crash sometimes.  Faster processors increase the opportunity for the problem to strike.

Hopefully my edits from last night will fix these problems for good.

Christmas lights notes

Submitted by wardr on Tue, 2014-12-09 22:28

PySerial will tell you that the following baud rates are supported:
(50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800, 500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000, 2500000, 3000000, 3500000, 4000000)

Improving Arduino's Serial Monitor Performance

Submitted by paul on Sat, 2014-12-06 20:57

Today I worked on the toughest Arduino bug... keeping the serial monitor from locking up or crashing with maximum speed printing from Teensy 3.1 and Arduino Due.

Here's Technical details and mini rant about Java performance.  Hopefully this (and other good work) will lead to future Arduino versions with a serial monitor that doesn't suck.