Owner manual

AT90C8534

I/O Memory

The I/O space definition of the AT90C8534 is shown in Table 1.

Note: Reserved and unused locations are not shown in the table.

The AT90C8534 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 and OUT, the I/O addresses $00 - $3F must be used. When addressing I/O reg-

isters 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 if accessed. Reserved I/O memory addresses

should never be written.

The I/O and peripherals control registers are explained in the following sections.

Table 1. AT90C8534 I/O Space

I/O Address (SRAM Address) Name Function

$3F ($5F) SREG Status REGister

$3E ($5E) SPH Stack Pointer High

$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 general Control Register

$33 ($53) TCCR0 Timer/Counter0 Control Register

$32 ($52) TCNT0 Timer/Counter0 (8-bit)

$2E ($4E) TCCR1 Timer/Counter1 Control Register

$2D ($4D) TCNT1H Timer/Counter1 High Byte

$2C ($4C) TCNT1L Timer/Counter1 Low Byte

$1F ($3E) EEARH EEPROM Address Register High Byte

$1E ($3E) EEARL EEPROM Address Register Low Byte

$1D ($3D) EEDR EEPROM Data Register

$1C ($3C) EECR EEPROM Control Register

$1B ($3B) PORTA Data Register, Port A

$1A ($3A) DDRA Data Direction Register, Port A

$10 ($30) GIPR General Interrupt Pin 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