Swiss AVR Knife

Step 2 ATtiny84 Microcontroller

Many projects use either the ATtiny2313 20-pin or the ATtiny85 8-pin microcontroller. I found the ATtiny2313 too big (for the enclosure) and the ATtiny85 too small (not enough memory, not enough output pins). The ATtiny84 is just right :-)

The ATtiny84 has 8K of programmable flash memory (enough to hold lots of small programs), 512K of EEPROM (for storing state between uses), up to 12 output pins (for the 9 LEDs, 2 channels of audio output, and a pushbutton switch), and lots of other goodies that aren't used in this project.

If you plan on adding programs, obtain a copy of the ATtiny84 datasheet. There are many instructional guides for learning to program this family of microcontroller on the Internet. For a helpful summary of microcontrollers, see How to Choose a Microcontroller.

Note The project described here does not actually have the MiniMenorah fully enabled. The MM requires nine output pins, the Brain Machine two, and the button to change state one, for a total of twelve. While the ATtiny84 can be configured to have twelve output pins, it is at the expense of the RESET pin. Disabling the RESET pin and making it I/O makes the ATtiny84 unable to be programmed with the USBtinyISP progammer (who hasn't done that :-) and requires High Voltage Programming. Everything is in place to enable the MM, but a different programmer is required, and I don't have one.