Technical Projects







Hardware Design and Overview

Theres not much to the hardware, but all of it is required!


The brains

The microcontroller is the ATtiny2313, a relatively new chip from Atmel. It is pin (but not functionally) compatible with the AT902313 and AT901200. Neither have bootloader capability, so you can't use JAvrProg to upload new code. However, you could theoretically make an ISP header in the prototype area and use an AVR ISP programmer to reprogram the chips. They don't have as many extras as the tiny2313, though.

The ATtiny2313 is pretty nice for $2, 1K of program memory (2K bytes), some EEPROM and SRAM. There is an internal 4MHz & 8MHz oscillator, analog comparator, 4 PWMs, a serial port, and two timers (one 8 bit, one 16 bit). You can read more about it at AVRFreaks. The only thing missing is an A/D channel or two. Quite sad.

The reset button is used to start the chip from address 0x0, for example when you want to enter the bootloader.

Serial Port
The ears
The serial port is how your upload code, and interface with a computer. It's comprised of a DB-9 female connector, a MAX232 (or compatible) serial level shifter, and 4x 1uF capacitors (for the MAX232). Every computer should have at least one DB-9 serial port. If not, perhaps a USB/Serial port converter is in order? The MAX232 coverts the 5V signal from the microcontroller into -/+12V signal necessary for serial connection to a computer.  
Power Source
The mouth
You can use either a power plug or battery, with a 2.1mm plug. The 5V regulator needs at least 7V to reasonably regulate the power. There are lower-dropout regulators available such as the LM2931 (minimum 5.3V input) The center pin is positive, the outer ring is ground.  
Breakout & Prototyping Area
The, um, prototyping area
You can add extra chips, sensors, A/D converters, LEDs, speakers, an extra fast oscillator, connectors, switches, LCDs, etc. The prototype area is mixed with analog and digital-style pads, and with 4 'rails' of GND and +5V. There's also a breakout strip with 14 pins, with connections to the microcontroller ports B0-7, A0, A1, and D2-5. If you want to use an external oscillator you must use pins A0, A1 for that. The rest are general purpose CMOS I/O ports that can sink or source approximately 20mA. Read the datasheet for more information, including information on possible uses for these pins (analog comparitor, clock-out, etc)