Kerry D. Wong

Since the current Arduino tools do not support in-circuit debugging, you will have to rely heavily on the serial print outs when tracking down those hard-to-find bugs unless you are one of those few elites whose code just works 100% every time. It is all good when you are doing your development when a computer is readily available. But what if you need to capture the outputs when you do not have the access to a computer? I found myself running into this situation quite often. Continue reading ‘Adding Off-Screen Buffer to Serial LCD Display’ »

One of the biggest advantages of FRAM (or FeRAM, Ferroelectric RAM) over EEPROM is that FRAM has a much higher write speed and typically can operate at bus speed. This means that no delay instructions are needed when performing write operations, which greatly reduces coding complexity and increases the overall throughput. Continue reading ‘Using FRAM as Nonvolatile Memory With Arduino’ »

MMA8453Q is a rather inexpensive accelerometer. It is significantly cheaper than many other 3-axis accelerometers (such as the popular LIS3LV02DL) and yet it offers a reasonably high 10 bits resolution and packs a rich set of features that simplifies designs and programming in many different applications. Continue reading ‘Interfacing MMA8453Q With Arduino’ »

A while back, I created an Arduino plugin for NetBeans so that I could use the full-fledged NetBeans IDE for all my Arduino projects. The approach I took was using the NetBeans project sample module method. Under the hood though, it is nothing more than a makefile and an source file template. Continue reading ‘Makefile for Arduino 1.0’ »

I have built quite a few (1,2,3) temperature measurement circuits in the past, but none of those has remote sensing capability. So I decided to make a wireless temperature sensor so that temperature measurements can be made anywhere within the range of the transmitter and the receiver. Continue reading ‘Building a Wireless Temperature Sensor’ »

Last time I showed a simple circuit that can be used to measure unknown thermistor parameters. The circuit is basically just a power MOSFET using a voltage and duty cycle controlled PWM signal to drive the gate and thus generates a temperature reference which is measured by both the unknown thermistor and the precision temperature sensor LM335. By measuring the voltage drop across the thermistor at different temperatures, we can obtain the R-T curve of the thermistor and thus estimate the parameters that define the R-T curve using some known models. Continue reading ‘Thermistor Parameter Measurement — II’ »

Over the years, I have gathered quite a few NTC and PTC thermistors. But most of them are unmarked so it would be difficult to use them in an accurate way without knowing the parameters. So I decided to build a simple circuit that can be used to trace the temperature-resistance curve, and the parameters can then be estimated using the measured data points. Continue reading ‘Thermistor Parameter Measurement — I’ »

The drive circuits for Unipolar stepper motors are usually very simple. In its simplest form, a transistor or MOSFET is used to drive each section of the windings. With this design, the control signal must be supplied programmatically to the four windings of the unipolar stepper motor via an MCU. Continue reading ‘A Unipolar Stepper Motor Driver’ »

DS28EC20 is a 20Kb 1-Wire EEPROM chip from Maxim. Like all other 1-wire devices, only a single pin is needed for both power and communication. In this blog posting, I will show you how to how to communicate with DS28EC20 using the popular Arduino platform. Continue reading ‘Interfacing DS28EC20 with Arduino’ »

Apress was kind enough to send me a copy of their recently released book “Arduino Robotics” a few weeks ago (ISBN13: 978-1-4302-3183-7, 628 Pages. Publication Date: July 18, 2011). So I thought I would read through and do a quick review on it. Continue reading ‘Arduino Robotics – A Short Review’ »

I recently dug up two sets of RF link transmitter/receiver modules from Sparkfun. I got these RF transmitters and receivers last year but have not had a chance to build anything with them yet. So I thought I would first wire up a simple transmitter/receiver to test their capabilities. Continue reading ‘RF Link 2400bps Receiver Output Buffer’ »

I wanted to be able to check my web server’s statistics periodically but did not want having to log on ever time when I wanted to do so. The simplest way to achieve this is to have the computer monitor on and run a server statistics program that outputs the information onto the screen. Continue reading ‘Building an Auxiliary Display’ »

Most of the recent Arduino and compatible boards use some kind of USB to UART hardware (e.g. FT232RL in Arduino Duemilanove and Atmega8U2 in the latest Arduino Uno) for interfacing with computer USB ports. Since ATmega328 has native UART support, building an Arduino that interfaces with the serial port (RS232) directly is arguably much easier. Continue reading ‘Arduino Serial Using LT1780’ »

I built a digital thermometer a couple of weeks ago. This thermometer uses an LM19 sensor calibrated for measuring a wide temperature range (-55 – 130 Celsius, -67 – 266 Fahrenheit) for outdoor temperature measurement and an SHT21 digital thermometer with humidity measurement for indoor use. Continue reading ‘A Dual Temperature Display With Humidity Measurement’ »

One of my old computers is used as a file backup server in my basement office. It is kept off most of the time and only powered on when I needed to sync up files. Continue reading ‘Wake On … IR’ »