AT90S8515-8PC Atmel, AT90S8515-8PC Datasheet - Page 10

• Manufacturer Part Number: AT90S8515-8PC
• Description: IC MCU 8K FLSH 8MHZ 40DIP
• Manufacturer: Atmel
• Series: AVR® 90Sr

Specifications of AT90S8515-8PC

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 6 V
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Data Converters: -

General-purpose
Register File
X-register, Y-register and
Z-register
10
AT90S8515
Figure 6 shows the structure of the 32 general-purpose working registers in the CPU.
Figure 6. AVR CPU General-purpose Working Registers
All the register operating instructions in the instruction set have direct and single-cycle
access to all registers. The only exception are the five constant arithmetic and logic
instructions SBCI, SUBI, CPI, ANDI and ORI between a constant and a register and the
LDI instruction for load immediate constant data. These instructions apply to the second
half of the registers in the register file (R16..R31). The general SBC, SUB, CP, AND and
OR and all other operations between two registers or on a single register apply to the
entire register file.
As shown in Figure 6, each register is also assigned a data memory address, mapping
them directly into the first 32 locations of the user Data Space. Although not being phys-
ically implemented as SRAM locations, this memory organization provides great
flexibility in access of the registers, as the X-, Y- and Z-registers can be set to index any
register in the file.
The registers R26..R31 have some added functions to their general-purpose usage.
These registers are address pointers for indirect addressing of the Data Space. The
three indirect address registers X, Y, and Z are defined as:
Figure 7. X-, Y-, and Z-registers
X - register
Y - register
Z - register
Registers
Purpose
Working
General
15
7
15
7
15
7
7
R29 ($1D)
R27 ($1B)
R31 ($1F)
R13
R14
R15
R16
R17
R26
R27
R28
R29
R30
R31
R0
R1
R2
…
…
0
0
0
0
7
7
7
Addr.
$0D
$1C
$1D
$00
$01
$02
$0E
$0F
$10
$11
$1A
$1B
$1E
$1F
R28 ($1C)
R26 ($1A)
R30 ($1E)
X-register high byte
Y-register high byte
Z-register high byte
X-register low byte
Y-register low byte
Z-register low byte
0841G–09/01
0
0
0
0
0
0