Atmel ATtiny25, Manual

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7598H–AVR–07/09
ATtiny25/45/85
If the program never enables an interrupt source, the Interrupt Vectors are not used, and regular
program code can be placed at these locations. The most typical and general program setup for
the Reset and Interrupt Vector Addresses in ATtiny25/45/85 is:
Address Labels Code Comments
0x0000 rjmp RESET ; Reset Handler
0x0001 rjmp EXT_INT0 ; IRQ0 Handler
0x0002 rjmp PCINT0 ; PCINT0 Handler
0x0003 rjmp TIM1_COMPA ; Timer1 CompareA Handler
0x0004 rjmp TIM1_OVF ; Timer1 Overflow Handler
0x0005 rjmp TIM0_OVF ; Timer0 Overflow Handler
0x0006 rjmp EE_RDY ; EEPROM Ready Handler
0x0007 rjmp ANA_COMP ; Analog Comparator Handler
0x0008 rjmp ADC ; ADC Conversion Handler
0x0009 rjmp TIM1_COMPB ; Timer1 CompareB Handler
0x000A rjmp TIM0_COMPA ;
0x000B rjmp TIM0_COMPB ;
0x000C rjmp WDT ;
0x000D rjmp USI_START ;
0x000E rjmp USI_OVF ;
0x000F RESET: ldi r16, low(RAMEND); Main program start
0x0010 ldi r17, high(RAMEND); Tiny85 has also SPH
0x0011 out SPL, r16 ; Set Stack Pointer to top of RAM
0x0012 out SPH, r17 ; Tiny85 has also SPH
0x0013 sei ; Enable interrupts
0x0014 <instr> xxx
... ... ... ...
10. I/O Ports
10.1 Introduction
All AVR ports have true Read-Modify-Write functionality when used as general digital I/O ports.
This means that the direction of one port pin can be changed without unintentionally changing
the direction of any other pin with the SBI and CBI instructions. The same applies when chang-
ing drive value (if configured as output) or enabling/disabling of pull-up resistors (if configured as
input). Each output buffer has symmetrical drive characteristics with both high sink and source
capability. The pin driver is strong enough to drive LED displays directly. All port pins have indi-
vidually selectable pull-up resistors with a supply-voltage invariant resistance. All I/O pins have
protection diodes to both V
CC
and Ground as indicated in Figure 10-1 . Refer to “Electrical Char-
acteristics” on page 150 for a complete list of parameters.