Using analog voltage references with Arduino

Little Bird Electronics posted an article about using an analog voltage reference with Arduino. This is a tool available when using an analog-to-digital converter. By setting up either an internal or external AREF, you can better use the ADC considering its resolution limitations. For instance, if you are measuring a signal that you know will always be below 2V, an external circuit, such as a voltage divider or an adjustable regulator, can give you a reference voltage just above that upper limit; say 2.5V. This way the 1024 divisions of resolution will be spread across your signal’s range, rather than just the lower half of the ADC readings.

Analog references are common to microcontrollers that have ADCs. Even if you’re not working with an Arduino, read through the article and use what you learn with your uC of choice.

Arduino + Java + Joystick

Interfacing your own hardware with a Java app couldn’t be easier than this example. [Pn] created this proof-of-concept using an Arduino, an analog joystick from a gaming controller, and a few lines of Java code. The Arduino reads an ADC value from the joystick’s x-axis and transmits it over the serial connection ten times a second. The Java program triggers on every serial event, parsing the data based on the @ symbol that the Arduino sends as a start and end condition.

We like this kind of example because there’s nothing extra involved. It lets you take the concept and run with it in any project imaginable. Be it a more complicated Joystick, or simple sensors that you’d like to interface with.

Multiple buttons and a pot on one pin

[Kevin Fodor] shares his method of reading multiple inputs on one pin of a microcontroller. The analog to digital convert function of the microcontroller is used to read a potentiometer but with some careful calculations a resistor network can be built into the circuit that provides a unique voltage value for each button pushed. The only real drawback is that the system cannot read multiple button presses at the same time. Theoretically up to ten momentary push buttons can be used but [Kevin] estimates that only four plus the potentiometer will work reliably.

[Thanks Charper]

Arduinome with many pots

[Aggaz] added 16 potentiometers to his Arduinome.The Arduinome is a monome clone based around the Arduino as a microprocessor. We seen some Arduinome builds in the past but [Aggaz's] work augments the physical interface.

Potentiometers used in circuit bending allow for manipulation of the sounds coming out of the circuits. In this case the pots are connected to the microcontroller instead of the sound generation circuitry which means you can do whatever you want with them depending on how creative you are with the code. So far he’s just starting to get the new set of interfaces to play nicely over the serial connection. This could end up being quite popular as it only requires the addition of a multiplexer IC, the potentiometers, and the knobs.

Arduino pH meter


[Carlos] sent us his project that uses an Arduino as a pH meter. In order to sense the acidity or alkalinity of a solution, a glass electrode is connected to the ADC of the Arduino through a fairly complicated calibration, amplification, and filtering circuit. Admittedly, it may not be cheaper or as accurate as some commercial models, but it is an open project and can be interfaced with a computer via USB.

Android Developer Challenge 2 open for submissions


Google has opened up a new Android Developer Challenge for submissions. About $2,000,000 in prize money is available, with $250,000 going to the best overall app. Submissions are due by August 31, leaving about a week to get apps in for judging. Time is short, but the prizes are big. Hopefully we’ll see some exciting things come from the contestants now that the community has grown since the previous ADC in 2008.

[via Phandroid]

Temperature sensing Munny


Here’s another nerdy present that was built for Valentine’s Day. [João Silva] created a temperature sensing Munny. A Munny is a vinyl toy made to be customized. Other than these Munny speakers, we haven’t seen them in many electronics projects. The LM35CZ temperature sensor has an analog output that connects to the ADC on the ATtiny15L. The microcontroller changes the RGB LED’s color based on the temperature: blue for cold, green for comfortable, and red for hot. It only flashes every three minutes to conserve the power in the coin cells. His one-off circuit board also includes an ISP header for programming. The Munny’s head looks like it does a great job diffusing the light.