I/o memory – Rainbow Electronics AT90LS2343 User Manual

Page 17

AT90S/LS2323/2343

1004D–09/01

Figure 23. On-chip Data SRAM Access Cycles

I/O Memory

The I/O space definition of the AT90S2323/2343 is shown in Table 2.

Note:

Reserved and unused locations are not shown in the table.

All AT90S2323/2343 I/Os and peripherals are placed in the I/O space. The I/O locations
are accessed by the IN and OUT instructions transferring data between the 32 general-
purpose working registers and the I/O space. I/O registers within the address range $00
- $1F are directly bit-accessible using the SBI and CBI instructions. In these registers,
the value of single bits can be checked by using the SBIS and SBIC instructions. Refer
to the instruction set section for more details. When using the I/O-specific commands IN

System Clock Ø

Data

Address

Prev. Address

Read

Write

Table 2. AT90S2323/2343 I/O Space

Address Hex

Name

Function

$3F ($5F)

SREG

Status REGister

$3D ($5D)

SPL

Stack Pointer Low

$3B ($5B)

GIMSK

General Interrupt MaSK register

$3A ($5A)

GIFR

General Interrupt Flag Register

$39 ($59)

TIMSK

Timer/Counter Interrupt MaSK register

$38 ($58)

TIFR

Timer/Counter Interrupt Flag register

$35 ($55)

MCUCR

MCU Control Register

$34 ($54)

MCUSR

MCU Status Register

$33 ($53)

TCCR0

Timer/Counter0 Control Register

$32 ($52)

TCNT0

Timer/Counter0 (8-bit)

$21 ($41)

WDTCR

Watchdog Timer Control Register

$1E ($3E)

EEAR

EEPROM Address Register

$1D ($3D)

EEDR

EEPROM Data Register

$1C ($3C)

EECR

EEPROM Control Register

$18 ($38)

PORTB

Data Register, Port B

$17 ($37)

DDRB

Data Direction Register, Port B

$16 ($36)

PINB

Input Pins, Port B