Shift registers are first cheep choice when you need to expand digital I/O pins say from one to eight. All you need is to clock serial data in in order to get all bits paralleled. Mika gives couple practical examples how this can be done using simple bit banging or SPI bus interface.

As microcontroller he have chosen Teensy board. As programming tool he selected Arduino IDE with Teensyduino add-on. In programming examples he used two types of shift registers – SN74HC595 and TPIC6B595. Second one is used in higher power applications. Both of them need three pins on input side: Data, Latch and Clock. As mentioned above it can be done using bit bang method where data mus be clocked in in program flow. So you need to write function that takes care of clock signal, latch and data output. This method is more obvious but occupies processor time. While using built in SPI you can set and forget. Data is shifted out automatically without using processor time.

You know that all apple gadgets have their price. And probably most of that price goes in to design not whats inside. If you don’t care of design then check out this Apple remote shield for Arduino. It can be assembled in no time.

All you need to do is to solder 5 push buttons and couple IR LEDs. And of course make it fir into Arduino board. After you flash the chip you’ll be able to send simple commands to your Mac, iPod and hopefully Apple TV.

When you feel that Atmega microcontroller runs out of juices and you don’t want to change to different type of microcontrollers like ARM then you can go with Xmega. Problem is that Xmega chip packages are less friendly for hobbyists but still usable. Having this in mind Brendan assembled Xmega breakout board which simply fits in to breadboard for fast prototyping.

The board includes ATXMega32a4u microcontroller alongwith power supply, USB port and I/Os aligned to fit nicely in to the breadboard. His intent is to make it more friendly for newbies by adding Arduino support for it. As a reference he’s using the XmegaDuino project. There is still lots of work to be done but you can start building one for yourself as you know it takes some time. [via dangerous prototypes]

Operating microcontrollers without interrupts is very inefficient. One of common used microcontrollers among hobbyists id AVR. Starters probably would go with Arduino board where AVR Atmega168/328 is used. It doesn’t matter weather you are programming in Arduino style or plain C it is advised to use interrupts. EngBlaze has written a tutorial on programming AVR timers using interrupts.

tutorial thoroughly goes through all information you may need including: what is timer, types of timers and finally running them in various modes. Once timers are set most of work is done in hardware with short interrupt routines where changes can be made. If you interested more about timers we have written couple tutorials on programming them using C.