Rainbow Electronics AT90LS8535 User Manual

Page 18

AT90S/LS8535

1041H–11/01

Note:

Reserved and unused locations are not shown in the table.

All AT90S8535 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 these addresses. 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 if 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 “1” back into any
flag read as set, thus clearing the flag. The CBI and SBI instructions work with registers
$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)

USR

UART Status Register

$0A ($2A)

UCR

UART Control Register

$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

Table 1. AT90S8535 I/O Space (Continued)

I/O Address

(SRAM Address)

Name

Function