Monthly Archives: December 2012


Fancy LED Christmas Tree

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Chris from PyroElectro has posted a tutorial on creating an LED Christmas tree controlled entirely by digital logic. His Christmas tree is cone shaped where 64 LEDs spiral around it from top to bottom. Each LED is individually controllable through a 74HC595 shift register output. The clock for shift register is generated using 555 timer IC. The LED Christmas tree can display two types of patters, one is more predictable and another random. Chris is also running a fund raising campaign on Kickstarter to get support for launching a free online Digital Electronics course. For past few years Chris has been

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TrH Meter: A DIY indoor thermometer plus hygrometer with adaptive brightness control implemented to 7-segment LED displays

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This project is about building a microcontroller-based digital room thermometer plus hygrometer that displays temperature and relative humidity on 4 large (1 inch) seven segment LED displays which adjust their brightness level according to the surrounding illumination. 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. An inexpensive DHT11 sensor is used to measure temperature and relative humidity. The microcontroller used in this project is PIC16F688, and it runs at 4 MHz clock generated from its internal source. A

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More PIC16F628A/PIC16F84A/PIC16F88/PIC16F1847 breakout board kits are available on Tindie

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The 18-pin PIC16F series microcontrollers are still very popular among hobbyists and beginners because of their compact size, low cost, and simplicity. The PIC16F1847 is the latest release in this series and is equipped with lot more peripherals and enhanced features than its predecessors. This breakout board provides all the basic elements that are required to get you going with your next project using PIC16F1847 or its predecessors, including PIC16F628A, PIC16F88, PIC16F84A, and PIC16F1827. More details of this board are found here: http://embedded-lab.com/blog/?p=5625 You can buy the breakout board kit with one PIC16F1847 microcontroller included for $13.00. Here’s the buying

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More SPI 4-digit seven segment LED displays are available

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Four digit SPI 7-segment LED displays are back in stock now on Tindie. The board has been revised from its earlier version and now contains an additional header connector to cascade multiple displays. The new header provides access to DOUT pin of MAX7219 driver IC. If you want to add a seven segment LED display to your project without giving up too many I/O resources, this board allows you to do that using only 3 I/O pins and it costs only $10. Tindie buying link for SPI 4-digit seven segment LED display  

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USB keyboard turns into an AVR programmer

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If you have an old USB keyboard that is just laying around and not usable anymore, you might consider converting it into an AVR programmer. This project from Steve is about constructing an AVR programmer using an USB keyboard controller board and an optocoupler. Steve writes, “Most keyboards have at least three indicator LEDs (Num-, Caps- and Scroll-Lock), which can be controlled from the host using a HID Set_Report request, and thus can be used as general purpose outputs. The inputs are a bit more tricky, since the keyboard uses a scan matrix divided in rows and columns. Most keyboards

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