34
AT94KAL Series FPSLIC
Rev. 1138G–FPSLI–11/03
AVR Core and Peripherals
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AVR Core
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Watchdog Timer/On-chip Oscillator
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Oscillator-to-Internal Clock Circuit
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Oscillator-to-Timer/Counter for Real-time Clock
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16-bit Timer/Counter and Two 8-bit Timer/Counters
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Interrupt Unit
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Multiplier
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UART (0)
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UART (1)
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I/O Port D (full 8 bits available on 144-pin or higher devices)
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I/O Port E
The embedded AVR core is a low-power CMOS 8-bit microcontroller based on the AVR RISC
architecture. The embedded AVR core achieves throughputs approaching 1 MIPS per MHz by
executing powerful instructions in a single-clock-cycle, and allows the system architect to opti-
mize power consumption versus processing speed.
The AVR core is based on an enhanced RISC architecture that combines a rich instruction set
with 32 x 8 general-purpose working registers. All the 32 x 8 registers are directly connected to
the Arithmetic Logic Unit (ALU), allowing two independent register bytes to be accessed in one
single instruction executed in one clock cycle. The resulting architecture is more code efficient
while achieving throughputs up to ten times faster than conventional CISC microcontrollers.
The embedded AVR core provides the following features: 16 general-purpose I/O lines, 32 x 8
general-purpose working registers, Real-time Counter (RTC), 3 flexible timer/counters with
compare modes and PWM, 2 UARTs, programmable Watchdog Timer with internal oscillator,
2-wire serial port, and three software-selectable Power-saving modes. The Idle mode stops
the CPU while allowing the SRAM, timer/counters, two-wire serial port, and interrupt system to
continue functioning. The Power-down mode saves the register contents but freezes the oscil-
lator, disabling all other chip functions until the next interrupt or hardware reset. In Power-save
mode, the timer oscillator continues to run, allowing the user to maintain a timer base while the
rest of the device is sleeping.
The embedded AVR core is supported with a full suite of program and system development
tools, including C compilers, macro assemblers, program debugger/simulators and evaluation
kits.