81 lines
4.0 KiB
NASM
81 lines
4.0 KiB
NASM
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;-------------------------------------------------------------------------------
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; File: Lab6_D2.asm
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; Description: The program demonstrates Press/Release using SW1 and LED1.
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; LED1 is initialized off.
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; When SW1 press is detected, a software delay of 20 ms
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; is used to implement debouncing. The switch is checked
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; again, and if on, LED1 is turned on until SW1 is released.
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;
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; Clocks: ACLK = 32.768kHz, MCLK = SMCLK = default DCO = 2^20=1,048,576 Hz
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; Platform: TI Experimenter's Board
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;
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; MSP430xG461x
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; -----------------
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; /|\| |
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; | | |
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; --|RST |
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; | P2.2|-->LED1(GREEN)
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; | P1.0|<--SW1
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;
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; Author: Aleksandar Milenkovic, milenkovic@computer.org
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; Date: September 14, 2018
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;-------------------------------------------------------------------------------
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.cdecls C,LIST,"msp430.h" ; Include device header file
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;-------------------------------------------------------------------------------
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.def RESET ; Export program entry-point to
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; make it known to linker.
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;-------------------------------------------------------------------------------
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.text ; Assemble into program memory.
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.retain ; Override ELF conditional linking
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; and retain current section.
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.retainrefs ; And retain any sections that have
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; references to current section.
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;-------------------------------------------------------------------------------
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RESET: mov.w #__STACK_END,SP ; Initialize stack pointer
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StopWDT: mov.w #WDTPW|WDTHOLD,&WDTCTL ; Stop watchdog timer
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;-------------------------------------------------------------------------------
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SetupP2:
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bis.b #004h, &P2DIR ; Set P2.2 to output
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; direction (0000_0100)
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bic.b #004h, &P2OUT ; Set P2OUT to 0x0000_0100 (ensure
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; LED1 is off)
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ChkSW1: bit.b #01h, &P1IN ; Check if SW1 is pressed
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; (0000_0001 on P1IN)
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jnz ChkSW1 ; If not zero, SW is not pressed
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; loop and check again
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Debounce:
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mov.w #2000, R15 ; Set to (2000 * 10 cc = 20,000 cc)
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SWD20ms: dec.w R15 ; Decrement R15
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nop
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nop
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nop
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nop
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nop
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nop
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nop
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jnz SWD20ms ; Delay over?
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bit.b #00000001b, &P1IN ; Verify SW1 is still pressed
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jnz ChkSW1 ; If not, wait for SW1 press
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LEDon: bis.b #004h, &P2OUT ; Turn on LED1
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SW1wait: bit.b #001h, &P1IN ; Test SW1
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jz SW1wait ; Wait until SW1 is released
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bic.b #004, &P2OUT ; Turn off LED1
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jmp ChkSW1 ; Loop to beginning
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;-------------------------------------------------------------------------------
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; Stack Pointer definition
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;-------------------------------------------------------------------------------
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.global __STACK_END
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.sect .stack
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;-------------------------------------------------------------------------------
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; Interrupt Vectors
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;-------------------------------------------------------------------------------
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.sect ".reset" ; MSP430 RESET Vector
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.short RESET
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.end
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