Arduino SMS device

Submitted by wade on Tue, 2013-12-31 02:25

I'm working on an SMS device that is programmed in the Arduino IDE and uses a tiny chorded keyboard for input, a SIM900 GSM module to accept standard AT commands, and a Nokia5110 LCD to display output. I stopped by earlier this evening and Paul (thanks Paul!) helped me debug. I've posted a thread on the Arduino.cc forum http://forum.arduino.cc/index.php?topic=206415 but basically I'm having trouble getting my sketch to run in the tiny 2K of RAM available on the ATmega328.

USB charging port for an ebike

Submitted by Scott Baker on Fri, 2013-12-20 13:53

I ride an electric bicycle that uses a 48V battery for it's energy source and there have been times when it would have been convenient to have a USB charging port (for charging my phone or any other other device that can recharge from a USB port).  So I built this USB charging port (basically a DC-to-DC converter capable of handling up to 60V input voltage).  I used the OSH Park circuit board prototyping service which worked perfectly.  I wrote an instructable about the build here:

Battery Pack Load

Submitted by paul on Tue, 2013-11-05 12:45

I purchased a cheap USB power pack, thinking it would be ideal for powering small projects.  But it automatically shuts off if the device isn't drawing a lot of power, since it's meant for charging cell phones.

Here's a 2 transistor circuit I built this morning that keeps it on with very little battery drain by using brief pulses.

Click "Read more" for the schematic, design details, and a PCB.....

Quality Audio on Teensy3 with Arduino

Submitted by paul on Mon, 2013-08-26 01:09

Over the last couple weeks I've been working on supporting quality audio (44.1 kHz, 16 bit) on Teensy3 using very simple Arduino style programming.  This weekend I added buttons and knobs to control parameters....

This work is still at an early stage.  I hope to publish a first alpha test version in about 1 month...

Edit: just a bit more info: The library manipulates audio with a collection of input, synthesis, processing and output objects that can be connected together in almost any way.  Audio connection objects automatically move the 16 bit data and run the synthesis and processing algorithms in the background, so the user's sketch isn't burdened with high bandwidth, real-time data manipulation.  The objects provide functions that can modify their behavior (volume, oscillator frequency, note on/off, modulation, etc) which can be used with extremely simple Arduino-style sketches, because the objects automatically handle all high speed data computation and movement in the background, triggered by interrupts and DMA transfers.

Designing a sytem to make excellent quality audio on Arduino with powerful features but also extremely easy has definitely turned out to be quite a challenge.  I'm still redesning the connection object's base class.  Much work remains, but now with I2S and PWM output working, .wav file playing and DDS sine wave generation all working, it really feels like it's starting to come together.  I hope to have the API stable enough (stable = unlikely to incompatibly change) for a first releast by October.