t13.asm

;;; ------- Constants for the ATtiny13 -------

; Memory map of ATtiny13:
;   *   Program memory: 0x0000 - 0x01FF (512 16-bit WORDS => 1kByte).
;   *   Data memory:
;       *   32 Registers (R0-R31):  0x0000 - 0x001F (32 bytes).
;       *   64 I/O Registers:       0x0020 - 0x005F (64 bytes).
;       *   64 SRAM bytes:          0x0060 - 0x009F (64 bytes).
;   *   Hence, RAMEND (typically used as top of stack) is 0x009F.
.equ RAMEND, 0x009F

.equ PORTB, 0x18    ; Port B output.
.equ DDRB,  0x17    ; Port B direction bits.
.equ PINB,  0x16    ; Port B input.
.equ OSCCAL, 0x31   ; Oscillator calibration.
.equ CLKPR, 0x26    ; Clock pre-scaler.
.equ SPL,   0x3d    ; Stack Pointer low byte (SPH not used on ATtiny13).
.equ MCUCR, 0x35    ; MCU Control Register.
.equ TIMSK0, 0x39   ; Timer 0 Interrupt Mask.
.equ GIMSK,	0x3b	; General Interrupt Mask Register (INT0 & pin-change interrupts).
.equ GIFR,	0x3a	; General Interrupt Flag Register.
.equ GTCCR, 0x28    ; General Timer/Counter Control Register.
.equ TCCR0A, 0x2f   ; Timer Control Register A.
.equ TCCR0B, 0x33   ; Timer Control Register B.
.equ OCR0A, 0x36    ; Timer/Counter Output Compare A.
.equ TCNT0, 0x32    ; Timer/Counter 0 value.
; Bit numbers of PORTB pins.
.equ PB0,   0
.equ PB1,   1
.equ PB2,   2
.equ PB3,   3
.equ PB4,   4
.equ PB5,   5
; Bit MASKS for PORTB pins:
.equ MPB0,  (1<<PB0)   ; 0b000001 => ATtiny13A pin 5
.equ MPB1,  (1<<PB1)   ; 0b000010 => ATtiny13A pin 6
.equ MPB2,  (1<<PB2)   ; 0b000100 => ATtiny13A pin 7
.equ MPB3,  (1<<PB3)   ; 0b001000 => ATtiny13A pin 2
.equ MPB4,  (1<<PB4)   ; 0b010000 => ATtiny13A pin 3
.equ MPB5,  (1<<PB5)   ; 0b100000 => ATtiny13A pin 1
; Half-words for X, Y, and Z 16-bit pointers:
.equ XR,    26  ; Name for use with MOVW
.equ XL,    26
.equ XH,    27
.equ YR,    28  ; Name for use with MOVW
.equ YL,    28
.equ YH,    29
.equ ZR,    30  ; Name for use with MOVW
.equ ZL,    30
.equ ZH,    31