I was looking for quite a time to interface the SD card and avr’s in my projects, fortunately here is this demonstrative project which can be a good starting point for anybody who needs to store large amounts of data. By implementing the FAT32 file system the stored data can be accessed directly from any PC, without the micro controller interface. This is very useful since you don’t have to carry a laptop or the entire data logger around.
The project is well documented, it really gives the insight needed to understand the FAT32 system and how SD card work, the authors project has serial interface so the SD card can be accessed trough the Hyperterminal. The Atmega8 might be short in memory for the advanced FAT32 handling, so for the actual device it is recommended about 32K flash capacity controller.
Just imagine, instead of the I2C 32kbyte external eeprom you can have 1G storage capacity, and with the FAT32 system you won’t need the serial interface, usually used to download the stored data.
ATmega with SD card: [link]
This is probably the most compact led matrix display ever, you need the ATtiny2313 and 8×8 Led matrix and off course two AA batteries for power. The micro controller is on the back of the display, soldered directly to the pins, since the voltage of two AA cells is around 3V you don’t need the current limiting resistors either. Just remember to use the low voltage type of micro controller like the ATTINY2313V-10PU the ATTINY2313-20PU won’t work, and in case of powering from 5V put some 100Ohm resistors in series with the leds.
This project can be easily adapted to other controller or display, but the ATtiny2313 and the LEDMS88R’s pin configuration fit together perfectly, no need for wire bridges to match the right pins.
With the 64 pixels you can’t display complex messages but there is enough resolution to achieve some eye catching animations, and the battery will last for two weeks. The size can be further reduced if you use small, coin shaped lithium cells instead of the bulky AA batteries.
Compact 64 pixel display: [link]
Arduino fan’s pay attention, the Mega brother is coming soon. No price or official release date available yet, since the picture is out already you won’t have to wait long to get your hands on this powerful development board.
It’s build around the atmega1280 micro controller, no more excuses that the code won’t fit or isn’t enough RAM, with its 14 PWM channels no motion control application is to complicated and via the 4 USART channels any inter communicating system can be solved.
I can already imagine projects with this board and the ethernet shield: web server, home automation server, security system.
Arduino Mega glance: [via]
Classic case: all the interesting projects revolve around micro controllers, so you start to dig around and found a dozen of tutorials, how-to’s schematics compilers and so on, you manage to make a simple programmer circuit which is guarantied by some expert from some forum, go out and buy two pieces of atmega8. You have the .hex file, connect the programmer and in that moment your head is full with the data sheet and different settings, you probably remember something about wrong fuse settings could damage the micro controller, and those bits are actually cleared when written, but since you are in a frenzy you click on some fuse settings and load… and then it happens, error reading from device, what could it be, maybe the other IC will work, same fuse settings and load… again the same error.
No more read or write operation, just like the micro controller wouldn’t be attached to the programmer. Most of the thinkers start to measure the supply voltage check the connections and realize at the end that they loaded the wrong fuse settings, and the IC is doomed.
Don’t throw them away in a hurry, you can reset the fuse settings using this parallel high voltage programmer. If you already have the Arduino board this low cost shield can come handy.
AVR fuse rescue with Arduino: [link]
The term POV is for Persistance of Vision, I don’t want to bore you with definitions or explications, just look at the next picture:
The project is very simple, first of all because this type of display is the easiest to build, and because the author made it only for three letters, this way everybody can understand the basic principles and extend the functionalities.
The source code should be optimized and added some position sensing to synchronize the image. The schematic isn’t available but form the source code is easy to reverse engineer, since each led is driven from one micro controller pin.
If you add an accelerometer then you can stabilize the image even when rotating by hand, off course the overall weight must be reduced. With some wireless link you could even refresh the image dynamically.
Simple handheld POV: [via] [link]
