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Hardware
Design and Overview |
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Theres not much to the hardware, but all of it is required! |
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Microcontroller
The
brains
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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.
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Serial
Port
The
ears
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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. |
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Power
Source
The
mouth
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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. |
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Breakout
& Prototyping Area
The,
um, prototyping area
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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) |
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