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Making a smart I2C DC motor controller

Posted on September 10, 2013 by R-B Leave a comment

A full-fledged DC motor controlling application requires a lot of I/O resources and MCU time. This project is about making a dedicated DC motor controllerthat would release the main microcontroller from this duty so that it could do other important tasks more efficiently. The controller uses Atmega168 as a slave I2C device that receives commands from a host MCU through I2C signal lines, and controls two DC motors using the L293D high-current H-driver chip. Separate PWM signals are used for each motor to achieve precise motor steering. The built-in motor steering library routines makes the motor control much easier.

Designing a RC snubber circuit

Posted on September 8, 2013 by R-B Leave a comment

In applications including power electronics, reverse recovery effects are very common and can induce unnecessary high-frequency oscillations in the circuit. This application document from NXP semiconductors describes the design of a simple “RC snubber circuit” for suppressing the oscillations. The technique requires the extraction of the circuit parasitic capacitance and inductance, and has been illustrated well with an example in the document.

DIY remote-controlled electronic scoreboard using LED strips

Posted on September 2, 2013 by R-B 2 comments

Most electronic scoreboards are expensive, and not everybody can afford them. This instructable is about a DIY scoreboard for softball that can be constructed for less than $100. The project uses LED strips to make seven segment digits, which are controlled by an Arduino Mega board through shift registers. The scoreboard displays the visitor and home team scores to 2 digits, the inning to 9 and the outs to 3. The display is controlled through an IR remote.

Temperature sensor accuracy improvement using a PIC MCU

Posted on September 1, 2013 by R-B Leave a comment

The accuracy of most of the current IC temperature sensors is about ±1°C at room temperature. However, at hot and cold temperatures, the uncertainty increases exponentially, resulting in a parabolic-shaped error curve. This application note describes a technique to enhance the accuracy of the sensor by modeling the error curve and use it to compensate for the sensor drift at a wide range of operating temperature. A PIC MCU is used to compute the equation for the curve and apply it to the sensor output to provide a more accurate temperature reading.

H-Bridge to drive white LED arrays directly from the AC mains supply

Posted on August 23, 2013 by R-B Leave a comment

The classical H-bridge circuit is widely popular in driving DC motors in robotics applications. This article talks about a novel application of the H-bridge circuit for driving white-LED arrays directly from the AC mains in full-wave current-limited mode to realize an excellent flicker-free, energy-efficient solid-state lamp. The circuit controls and maintains the LED excitation current in both negative and positive half cycles of the excitation voltage to a constant level by way of electronic switches operating alternately during the positive and negative excursion of the excitation voltage.

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