Monthly Archives: July 2012


More MAX7219 based serial seven segment LED displays are available now!

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Due to high demand of the MAX7219 based serial 4-digit seven segment LED displays, I recently ordered more PCBs for this. You can now order a complete kit for $11.99 and an assembled module for $13.99. Both prices include free shipping within the continental United States. The display is based on the MAX7219 driver chip that supports 3-wire SPI interface. You can find an interfacing example for PIC12F683 microcontroller here. The example code is written in C and therefore, it can be easily implemented to any other microcontroller family. This display module is available for purchase as a kit. The

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chipKIT Project 2: Temperature and relative humidity logger

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This project is about building a PC-based temperature and relative humidity logger using the chipKIT Uno32 board and the DHT11 sensor. The project setup requires no additional wires (other than the USB cable) and components; the DHT11 sensor is directly plugged into four I/O pins of the Uno32 board and the project is ready to go. This could be a handy and an easiest way to setup an ambient room monitoring system for a server room. The Uno32 reads the temperature and relative humidity from the DHT11 sensor at preset interval and sends the data to PC through the USB-UART

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Add a reminder to your washer

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Most washers don’t have a built-in reminder. Mine doesn’t have either and a lot of time I have forgot my clothes inside it after they are done. The wet clothes smell really bad if they are left inside the washer for a while. If you have a similar issue with your washer, you might want to build this project which adds an audible reminder to the washer that will beep when the clothes are done. This project is based on an accelerometer that continuously senses the vibration of the washer when it is running. When the clothes are done, the washer stops

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Temperature and relative humidity display with adaptive brightness control

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The objective of this project is to illustrate a technique of implementing adaptive brightness control to seven segment LED displays. It consists of a closed loop system that continuously assesses ambient light condition using an inexpensive light-dependent resistor (LDR) and uses that information to adjust the brightness of the display. For the proof of concept, the technique is applied to construct a digital temperature and relative humidity meter that adapts the brightness of the seven segment LED displays to the surrounding lighting conditions. There are 8 seven segment LED displays used in this project and they are all driven by

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