AT90S4434 Datasheet, PDF (4/10 Pages) ATMEL Corporation – 8-Bit Microcontroller with 4K/8K Bytes In-System Programmable Flash

Figure 1. Oscillator Connections
Figure 2. External Clock Drive Configuration
Architectural Overview
The fast-access register file concept contains 32 x 8-bit
general purpose working registers with a single clock cycle
access time. This means that during one single clock cycle,
one Arithmetic Logic Unit (ALU) operation is executed. Two
operands are output from the register file, the operation is
executed, and the result is stored back in the register file -
in one clock cycle.
Six of the 32 registers can be used as three 16-bits indirect
address register pointers for Data Space addressing -
enabling efficient address calculations. One of the three
address pointers is also used as the address pointer for the
constant table look up function. These added function reg-
isters are the 16-bits X-register, Y-register and Z-register.
Figure 3. The AT90S4434/8535 AVR Enhanced RISC Architecture
AVR AT90S4434/8535 Architecture
Data Bus 8-bit
2K/4K X 16
Program
Memory
Instruction
Register
Instruction
Decoder
Control Lines
Program
Counter
Status
and Control
32 x 8
General
Purpose
Registrers
ALU
256/512 x 8
Data
SRAM
256/512 x 8
EEPROM
32
I/O Lines
Interrupt
Unit
SPI
Unit
Serial
UART
8-bit
Timer/Counter
16-bit
Timer/Counter
with PWM
8-bit
Timer/Counter
with PWM
Watchdog
Timer
Analog to Digital
Converter
Analog
Comparator
4 AT90S/LS4434 and AT90S/LS8535