Rainbow Electronics AT90LS4433 User Manual

Page 18

AT90S/LS4433

1042G–AVR–09/02

Note:

1. Reserved and unused locations are not shown in the table.

All AT90S4433 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 pur-
pose 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
and OUT, the I/O addresses $00 - $3F must be used. When addressing I/O Registers as
SRAM, $20 must be added to this address. All I/O Register addresses throughout this
document are shown with the SRAM address in parentheses.

For compatibility with future devices, reserved bits should be written to zero when
accessed. Reserved I/O memory addresses should never be written.

Some of the Status Flags are cleared by writing a logical “1” to them. Note that the CBI
and SBI instructions will operate on all bits in the I/O Register, writing a one back into
any flag read as set, thus clearing the flag. The CBI and SBI instructions work with reg-
isters $00 to $1F only.

The I/O and Peripherals Control Registers are explained in the following sections.

$17 ($37)

DDRB

Data Direction Register, Port B

$16 ($36)

PINB

Input Pins, Port B

$15 ($35)

PORTC

Data Register, Port C

$14 ($34)

DDRC

Data Direction Register, Port C

$13 ($33)

PINC

Input Pins, Port C

$12 ($32)

PORTD

Data Register, Port D

$11 ($31)

DDRD

Data Direction Register, Port D

$10 ($30)

PIND

Input Pins, Port D

$0F ($2F)

SPDR

SPI I/O Data Register

$0E ($2E)

SPSR

SPI Status Register

$0D ($2D)

SPCR

SPI Control Register

$0C ($2C)

UDR

UART I/O Data Register

$0B ($2B)

UCSRA

UART Control and Status Register A

$0A ($2A)

UCSRB

UART Control and Status Register B

$09 ($29)

UBRR

UART Baud Rate Register

$08 ($28)

ACSR

Analog Comparator Control and Status Register

$07 ($27)

ADMUX

ADC Multiplexer Select Register

$06 ($26)

ADCSR

ADC Control and Status Register

$05 ($25)

ADCH

ADC Data Register High

$04 ($24)

ADCL

ADC Data Register Low

$03 ($23)

UBRRHI

UART Baud Rate Register High

Table 2. AT90S4433 I/O Space

(1)

(Continued)

I/O Address

(SRAM Address)

Name

Function