AUG13
AVR based video game platform
For all electronic gamers there is a new game platform for game development.
Platform is based on AVR microcontroller without any other external active components, and it's quite impressive. Color picture is generated on RGB monitor with simple D/A converter made out of 9 resistors. Along with hardware author has also developed a very powerful API that allows us to code our own games. Here we can see a Super Mario clone that runs on ATmega168 and it works pretty smoothly!
Source: Jaromir Dvorak
AUG5
Rotating LED display in color
As we didn't see enough of these rotating LED displays... Anyway, here is another one but very nicely built and in multiple colors.
Dual-color LEDs (red and green) are used to produce three colors: red, green and orange/yellow. LEDs are controlled with Atmega8 via 74HC595D shift registers and motor used for rotating the board is from an old fan. The most interesting thing about this project is the way the command data (message to be displayed) is sent to the microcontroller; author used a fiber-optic thread to transfer IR light from above and through the rotating shaft to the IR receptor on the board. All in all, an excellent project!
Source: Aki Korhonen
AUG4
Electronic Temperature-Controlled Relay
Today in embedded world it is pretty hard to find an analog DIY project, even though in this project "digitalisation" would be an overkill.
So here is a pretty simple device that works as a thermostat in temperature range of 0-100 degrees Celsius. LM35 is used as temperature sensor whose output voltage changes with temperature from 0V (0 degrees Celsius) to 1000mV (100 degrees Celsius). TL431 precision voltage reference is used to provide with precise reference voltage for comparator, that will be compared with voltage from temperature sensor.
Source: escol.com.my
AUG3
Dual USB oscilloscope with ATtiny45
Quality oscilloscopes cost some money but there are also good USB versions available on the market. Now how about a $5 USB version that you can build yourself?
Here is a dual input AD converter that connects to PCs USB port. Windows application plots analog values received from ATtiny45's 10-bit A/D converters. Application is written in Visual Studio 2005 C# and the source code is available for download on the project page. Microcontroller's firmware is written in C and is also available for download. Sampling frequency does not exceed 100 samples/second, so this device certainly doesn't have the performances of those that we can buy from stores but it sure can be helpful!
Source: Yves Lebrac aka Jacques L.
JUL31
RS232 to infrared interface
Transmission of weak infrared signals could now be possible even through the Internet with this little device. A custom client-server application could be made that simply sends serial data over any kind of link.
So, here is a device that transforms received infrared signals into RS232 serial data. It also transforms received RS232 and sends it through the infrared LED that is on the device. Two of these devices basically form an infrared repeater through the RS232 port based on Microchip's PIC12F683. It is possible to send raw data as well as remote control commands! Pretty sweet device.
Source: Andrew M. Bishop
JUL30
Lazy man's USB RFID reader
When we want to connect our RFID reader IC to PC it would be great if it could be powered by and connected to USB port. To avoid building our serial to usb converter we can simply purchase one from a local PC store. In that case we need UART-TTL voltage converter.
RFID reader modules that we can purchase usually work with TTL voltage levels and are powered from 5V. As the serial to usb converter module offers "real" UART port with UART voltages, we also need MAX232 to make it compatible with our 5V reader. This can be done a bit differently but it involves opening and hacking into a serial to usb converter. Read on to see how it can be done to save some money and get an extra IC!
JUL29
Decoding 4x4 keypad with AVR and 74C922
Keypad decoding or scanning using microcontroller is, lets face it - nothing new. The thing is that sometimes it can be a real pain when smaller microcontroller with not enough I/O pins is being used or when microcontroller has some more important task to do besides scanning the keypad.
Anyway, here is a project that scans 4x4 keypad using Atmel's 4+4 I/O pins (the usual method) and by using a special IC designed for that purpose: MM74C922. This IC is directly connected to keypad rows and columns with it's 4+4=8 pins, and on it's 4 digital output BCD pins it provides information about which key is pressed on keypad. Along with those 4 data pins it also has IRQ pin that can generate interrupt in microcontroller when key press is detected. Keypad scanning has never been easier!
Source: nevdull
JUL28
Compact fluorescent lamp schematics
Fluorescent lamps are very popular during these green days, even our Electra is giving them away for free after paying the electric bill.
They usually come in these color temperatures: Warm white (2700K), Cool white (4000K) and Daylight (6000K). Apart from those cheap fluo lamps that you can buy, there are also more expensive, branded ones. On this page, there is a big collection of most popupar (if not all) fluorescent lamps: Bigluz, Isotronic, Luxtek, Maway, Maxilux, Polaris, BrownieX, Philips Ecotone, Ikea, Osram Dulux El, Osram Dulux El, Eurolite and Sinecan 5, so fixing one does make sense when you can easily figure out what's wrong with it!
Source: Pavouk
