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BYU CS/ECEn 124 MSP430 Examples 1

Topics to Cover«

F2013 Blinky Example

Lab 4: Blinky Lab

Example 2: Interrupts w/Timer_A

Example 3: S/W PWM w/Timer_A

Example 4: Watchdog Clock

Example 5: Watchdog PWM

Example 6: SW Switch Debounce

Example 7: Timer_B S/W PWM

Recursive Line Draw

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BYU CS/ECEn 124 MSP430 Examples 2

F2013 Blinky Example

;*******************************************************************************; CS/ECEn 124 Lab 1 - blinky.asm: Software Toggle P1.0;*******************************************************************************

.cdecls C,LIST, "msp430x20x3.h" ; MSP430F2013

;------------------------------------------------------------------------------.text ; beginning of executable code

;------------------------------------------------------------------------------RESET: mov.w #0x0280,SP ; init stack pointer

  mov.w #WDTPW+WDTHOLD,&WDTCTL ; stop WDT  bis.b #0x01,&P1DIR ; set P1.0 as output

  mainloop: xor.b #0x01,&P1OUT ; toggle P1.0  mov.w #0,r15 ; use R15 as delay counter

delayloop: dec.w r15 ; delay over?jnz delayloop ; n

jmp mainloop ; y, toggle led 

;------------------------------------------------------------------------------; Interrupt Vectors;------------------------------------------------------------------------------

.sect ".reset" ; MSP430 RESET Vector

.short RESET ; start address

.end 

Systematic Decomposition

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BYU CS/ECEn 124 MSP430 Examples 3

Add 2nd Delay Loop

;*******************************************************************************; CS/ECEn 124 Lab 1 - blinky.asm: Software Toggle P1.0;*******************************************************************************

.cdecls C,LIST, "msp430x20x3.h" ; MSP430F2013delay .set 0;------------------------------------------------------------------------------

.text ; beginning of executable code;------------------------------------------------------------------------------RESET: mov.w #0x0280,SP ; init stack pointer

  mov.w #WDTPW+WDTHOLD,&WDTCTL ; stop WDT  bis.b #0x01,&P1DIR ; set P1.0 as output

  mainloop: xor.b #0x01,&P1OUT ; toggle P1.0  mov.w #delay,r15 ; use R15 as delay counter

delayloop: dec.w r15 ; delay over?jnz delayloop ; n

delay2: dec.w r15jnz delay2

jmp mainloop ; y, toggle led 

;------------------------------------------------------------------------------; Interrupt Vectors;------------------------------------------------------------------------------

.sect ".reset" ; MSP430 RESET Vector

.short RESET ; start address

.end 

Systematic Decomposition

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BYU CS/ECEn 124 MSP430 Examples 4

LEDs

6 LED¶s on eZ430X Development Board

P1.0 Red LED eZ430-RF2500

P1.1 Green LED eZ430-RF2500

P2.6 LED #1 (Green)

P2.7 LED #2 (Orange) P3.3 LED #3 (Yellow)

P4.6 LED #4 (Red)

Port bits must be enabled for output by writing a 1 to the

port direction register 

bis.b #0x03,&P1DIR ; eZ430-RF2500 LED's bic.b #0xc0,&P2SEL ; select GPIO

bis.b #0x40,&P2DIR ; LED #1 (P2.6)

bis.b #0x80,&P2DIR ; LED #2 (P2.7)

bis.b #0x08,&P3DIR ; LED #3 (P3.3)

bis.b #0x40,&P4DIR ; LED #4 (P4.6)

Device: LED

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LEDs

Turn LED off by writing a 0 to the port pin bic.b #0x03,&P1OUT ; eZ430-RF2500 LED's bic.b #0x40,&P2OUT ; LED #1 (P2.6) bic.b #0x80,&P2OUT ; LED #2 (P2.7) bic.b #0x08,&P3OUT ; LED #3 (P3.3) bic.b #0x40,&P4OUT ; LED #4 (P4.6)

Turn LED on by writing a 1 to the port pin bis.b #0x03,&P1OUT ; eZ430-RF2500 LED's bis.b #0x40,&P2OUT ; LED #1 (P2.6) bis.b #0x80,&P2OUT ; LED #2 (P2.7) bis.b #0x08,&P3OUT ; LED #3 (P3.3) bis.b #0x40,&P4OUT ; LED #4 (P4.6)

Toggle LED by XOR¶ing a 1 to the port pin xor.b #0x03,&P1OUT ; eZ430-RF2500 LED's xor.b #0x40,&P2OUT ; LED #1 (P2.6) xor.b #0x80,&P2OUT ; LED #2 (P2.7) xor.b #0x08,&P3OUT ; LED #3 (P3.3) xor.b #0x40,&P4OUT ; LED #4 (P4.6)

Device: LED

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BYU CS/ECEn 124 MSP430 Examples 6

Lab 4: Blinky Lab

Lab 4: Blinky

;*******************************************************************************; CS/ECEn 124 Lab 4 - blinky.asm ;*******************************************************************************; cycles = ---; MCLK = --- cycles / 10 seconds = --- Mhz; CPI = MCLK / ---; MIPS = MCLK / CPI / 1000000 = --- MIPS

.cdecls C,LIST, "msp430x22x4.h" ; MSP430F2274COUNT .equ 0 ; delay count

;------------------------------------------------------------------------------.text ; beginning of executable code;------------------------------------------------------------------------------RESET: mov.w #0x0280,SP ; 2 init stack pointer

  mov.w #WDTPW+WDTHOLD,&WDTCTL ;5 stop WDT  bis.b #0x01,&P1DIR ;4 set P1.0 as output

  mainloop: xor.b #0x01,&P1OUT ;4 toggle P1.0  mov.w #COUNT,r15 ;1 use R15 as delay counter

delayloop: dec.w r15 ; 1 delay over?jnz delayloop ; 2 n

jmp mainloop ; 2 y, toggle led 

;------------------------------------------------------------------------------; Interrupt Vectors;------------------------------------------------------------------------------

.sect ".reset" ; MSP430 RESET Vector

.short RESET ; start address

.end 

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BYU CS/ECEn 124 MSP430 Examples 7

.cdecls C,LIST, "msp430x20x3.h" ; MSP430F2013DELAY .equ (50/8)

.text ; beginning of codeRESET: mov.w #0x0280,SP ; init stack pointer

  mov.w #WDTPW+WDTHOLD,&WDTCTL ; stop WDT  bis.b #0x01,&P1DIR ; set P1.0 as output

  mainloop: xor.b #0x01,&P1OUT ; toggle P1.0  push.w #DELAY ; pass delay count on stack

call #delay ; call delay subroutinejmp mainloop

; delay subroutine: stack usage 4| DELAY | \; 2| ret | subroutine frame (6 bytes); (SP) => 0| r15 | /delay: push.w r15 ; callee-save

  mov.w #0,r15 ; use R15 as inner counter

delay02: dec.w r15 ; inner delay over?jne delay02 ; n

dec.w 4(SP) ; y, outer done?jne delay02 ; n

  pop.w r15 ; y, restore register(s)  mov.w @SP+,0(SP) ; pop input delay countret ; return from subroutine

.sect ".reset" ; MSP430 RESET Vector

.word RESET ; start address

.end 

Example 1a: Activation Recor d

4(SP) = delay count2(SP) = return address0(SP) = r 15

Activation Recor d

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BYU CS/ECEn 124 MSP430 Examples 8

.cdecls C,LIST, "msp430x20x3.h" ; MSP430F2013DELAY .equ (50/8)

.text ; beginning of codeRESET: mov.w #0x0280,SP ; init stack pointer

  mov.w #WDTPW+WDTHOLD,&WDTCTL ; stop WDT  bis.b #0x01,&P1DIR ; set P1.0 as output

  mainloop: xor.b #0x01,&P1OUT ; toggle P1.0  push.w #DELAY ; pass delay count on stackcall #delay ; call delay subroutine

jmp mainloop

; delay subroutine: stack usage 6| DELAY | \; 4| ret | subroutine frame (8 bytes); 2| r12 | /(activation record); (SP) => 0| r15 |/delay: push.w r12 ; callee-save

  push.w r15  mov.w 6(SP),r12 ; get delay count  mov.w #0,r15 ; use R15 as inner counter

delay02: dec.w r15 ; delay over?jne delay02 ; n

dec.w r12 ; y, done?jne delay02 ; n

  pop.w r15 ; y, restore registers  pop.w r12  mov.w @SP+,0(SP) ; pop input delay countret ; return from subroutine

.sect ".reset" ; MSP430 RESET Vector

.word RESET ; start address.end 

Example 1b: Activation Recor d

6(SP) = delay count4(SP) = return address2(SP) = r 120(SP) = r 15

Activation Recor d

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.cdecls C,LIST, "msp430x20x3.h" ; MSP430F2013DELAY .equ (50/8)

.text ; beginning of codeRESET: mov.w #0x0280,SP ; init stack pointer

  mov.w #WDTPW+WDTHOLD,&WDTCTL ; stop WDT  bis.b #0x01,&P1DIR ; set P1.0 as output

  mainloop: xor.b #0x01,&P1OUT ; toggle P1.0  push.w #DELAY ; pass delay count on stackcall #delay ; call delay subroutinejmp mainloop

; delay subroutine: stack usage 4| DELAY | \; 2| ret | subroutine frame (6 bytes); (SP) => 0| counter | /delay: sub.w #2,SP ; activate local variable

  mov.w #0,0(SP) ; use as inner counter

delay02: dec.w 0(SP) ; delay over?jne delay02 ; ndec.w 4(SP) ; y, done?

jne delay02 ; nadd.w #2,SP ; y, deactivate local variable  mov.w @SP+,0(SP) ; pop input delay countret ; return from subroutine

.sect ".reset" ; MSP430 RESET Vector

.word RESET ; start address

.end 

Example 1c: Activation Recor d

4(SP) = delay count2(SP) = return address0(SP) = local variable

Activation Recor d

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Example 2: Interrupts w/Timer_A

cdecls C,LIST, "msp430x20x3.h" ; MSP430F2013TA_CTL .set TASSEL_2+ID_3+MC_1+TAIE ; 000000 10 11 01 000 1 = SMCLK,/8,UP,IETA_FREQ .set 0xffff ; clocks

;------------------------------------------------------------------------------.text ; beginning of executable code

RESET: mov.w #0x0280,SP ; init stack pointer  mov.w #WDTPW+WDTHOLD,&WDTCTL ; stop WDT  bis.b #0x01,&P1DIR ; set P1.0 as output

clr.w &TAR ; reset timerA   mov.w #TA_CTL,&TACTL ; set timerA control reg  mov.w #TA_FREQ,&TACCR0 ; set interval (frequency)  bis.w #LPM0+GIE,SR ; enter LPM0 w/interruptsjmp $

TA_isr: ; timer A ISR   bic.w #TAIFG,&TACTL ; acknowledge interruptxor.b #0x01,&P1OUT ; toggle P1.0

reti

;------------------------------------------------------------------------------; Interrupt Vectors

.sect ".int08" ; timer A section

.word TA_isr ; timer A isr

.sect ".reset" ; MSP430 RESET Vector

.word RESET ; start address

.end 

Blinky Example

TASSEL_2 = SMCLK

ID_3 = /8

 MC_1 = UP Mode

Enable Interrupt

Acknowledge Interrupt(Put its hand down)

Put the processor tosleep!

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Example 3: S /W PWM w/Timer_A

.cdecls C,LIST,"msp430x20x3.h"SMCLK .set 1200000 ; 1200000 clocks / second TA_CTL .set TASSEL_2+ID_0+MC_1+TAIE ; SMCLK, /1, UP, IETA_FREQ .set 120 ; FREQ / SMCLK = 0.0001 = 100 us

.bss cnt,2 ; counter variable

.textRESET: mov.w #0x0280,SP ; init stack pointer

  mov.w #WDTPW+WDTHOLD,&WDTCTL ; stop watchdog  bis.b #0x01,&P1DIR ; set P1.0 as outputclr.w &TAR ; reset timerA 

  mov.w #TA_CTL,&TACTL ; set timerA control reg  mov.w #TA_FREQ,&TACCR0 ; set interval (frequency)  bis.w #LPM0+GIE,SR ; enter LPM0 w/interruptsjmp $ ; will never get here!

TA_isr: bic.w #TAIFG,&TACTL ; acknowledge interruptinc.w &cntcmp.w #10,&cnt ; time to pulse?jlo TA_isr2 ; n

clr.w &cnt ; y, reset counter  bis.b #0x01,&P1OUT ; turn on

jmp TA_isr4

TA_isr2: bic.b #0x01,&P1OUT ; turn off

TA_isr4: reti ; return from interrupt

.sect ".int08" ; timer A section

.word TA_isr ; timer A isr

.sect ".reset" ; MSP430 RESET Vector

.short RESET ; start address

.end 

LED Intensity

Acknowledgeneeded

10% DutyCycle

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Example 4: Watchdog Clock

.cdecls C,LIST,"msp430x20x3.h"SMCLK .set 1200000 ; 1.2 Mhz clock  WDT_CTL .set WDT_MDLY_8 ; WDT SMCLK, 8 ms (@1 Mhz)  WDT_CPS .set SMCLK/8000 ; WD clocks / second count

; Data Section ------------------------------------------------------------.bss WDTSecCnt,2 ; WDT second counter

; Code Section ------------------------------------------------------------.text

RESET: mov.w #0x280,SP ; initialize stack pointer  mov.w #WDT_CTL,&WDTCTL ; set WD timer interval

  mov.w #WDT_CPS,&WDTSecCnt ; initialize 1 sec WD counter  bis.b #WDTIE,&IE1 ; enable WDT interrupt  bis.b #0x01,&P1DIR ; P1.0 output  bis.w #GIE,SR ; enable interrupts

loop: ;<< program >> jmp loop ; loop indefinitely

; Watchdog ISR ------------------------------------------------------------  WDT_ISR: dec.w &WDTSecCnt ; decrement counter, 0?

jne WDT_02 ; n

  mov.w #WDT_CPS,&WDTSecCnt ; y, re-initialize counterxor.b #0x01,&P1OUT ; toggle P1.0

  WDT_02: reti ; return from interrupt

; Interrupt Vectors -------------------------------------------------------.sect ".int10" ; Watchdog Vector.word WDT_ISR ; Watchdog ISR .sect ".reset" ; PUC Vector.word RESET ; RESET ISR .end 

Watchdog

8 ms (@1 MHz SMCLK)

Enable WD Interrupts

No acknowledgeneeded

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Example 5: Watchdog PWM

.cdecls C,LIST,"msp430x22x4.h" ; include c header  WDT_CLK .set 500 ; 500 Mhz WD clock (@1 Mhz)STACK .set 0x0600 ; stack

.bss WDTSecCnt,2 ; WDT second counter

.bss buzzON,1 ; buzzer on flag

.text ; program sectionRESET: mov.w #STACK,SP ; initialize stack pointer

  mov.w #WDT_MDLY_0_5,&WDTCTL ; set WD timer interval to 0.5 ms  mov.w #WDT_CPS,&WDTSecCnt ; initialize 1 sec WD counter  mov.b #WDTIE,&IE1 ; enable WDT interrupt  bis.b #0x01,&P1DIR ; P1.0 output  bis.b #0x20,&P4DIR ; P4.5 output (transducer)clr.b &buzzON ; turn off buzzer

  bis.w #LPM0+GIE,SR ; enable interrupts / sleepjmp $ ; (should never get here!)

  WDT_ISR: cmp.b #0,&buzzON ; buzzer on?jeq WDT_02 ; n

xor.b #0x20,&P4OUT ; y, use 50% PWM 

  WDT_02: dec.w &WDTSecCnt ; decrement counter, 0?jne WDT_04 ; n

  mov.w #WDT_CPS,&WDTSecCnt ; y, re-initialize counterxor.b #0x01,&P1OUT ; toggle P1.0xor.b #0xff,&buzzON ; toggle buzzer on/off

  WDT_04: reti ; return from interrupt

.sect ".int10" ; Watchdog Vector

.word WDT_ISR ; Watchdog ISR 

.sect ".reset" ; PUC Vector

.word RESET ; RESET ISR 

.end 

Speaker (Transducer )

PWM when buzzON is

non-zero

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;**********************************************************************; Switch debounce routine;DB_TIME .set 10 ; 10 ms debounce timeDB_CYCS .set 13 ; instruction cycles for delayDB_DELAY .set DB_TIME*myCLOCK/DB_CYCS/1000 ; delay count

debounce_switch:

  push r15 ; callee save

deb02: mov.b &P2IN,r12 ; read switchesxor.b #0x0f,r12 ; SW1-4and.b #0x0f,r12 ; any switch low?jne deb02 ; y, wait until all off

deb04: mov.w #DB_DELAY,r15 ; minimum delay

deb06: mov.b &P2IN,r12 ; read switchesxor.b #0x0f,r12 ; SW1-4and.b #0x0f,r12 ; all switches high?jeq deb04 ; n, restart delay

dec.w r15 ; y, long enough delay?jne deb06 ; n, keep going

  pop r15 ; y, switches debounced ret

Example 6: SW Switch Debounce

Reset timing counter if 

and of theswitches

read 0

Switch Debounce

Return if 

R15

 countsdown to 0

Wait untilall

switches

off 

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Example 7: Timer_B S /W PWM

Timer B interrupts used to modulate transducer at 440 Hz.cdecls C,LIST,"msp430x22x4.h"SMCLK .set 1200000 ; 1200000 clocks / second TIME_A3 .set 1000000/440/2 ; A = 440 HzTB_CTL .set TBSSEL_2+ID_0+MC_1+TBIE ; SMCLK, /1, UP, IETB_FREQ .set SMCLK/TIME_A3 ; clocks / 440 Hz

reset: mov.w #0x0600,SP ; initialize SP  mov.w #WDTPW+WDTHOLD,&WDTCTL ; stop WDT  bis.b #0x20,&P4DIR ; P4.5 transducer outputclr.w &TBR ; reset timerB  mov.w #TB_CTL,&TBCTL ; set timerB control reg  mov.w #TB_FREQ,&TBCCR0 ; set interval (frequency)  bis.w #LPM0+GIE,SR ; enter LPM0 w/interruptsjmp $ ; will never get here!

TB_isr: bic.w #TBIFG,&TBCTL ; acknowledge interruptxor.b #0x20,&P4OUT ; toggle (50% duty cycle)reti

.sect ".int12" ; timer B section

.word TB_isr ; timer B isr

.sect ".reset" ; reset vector section

.word reset ; reset vector ISR 

.end 

Timer B InterruptService Routine

Pulse Width Modulation (S /W)

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Step 1: Start Simple

Tone Scale Example

.cdecls C,LIST,"msp430x22x4.h"STACK .set 0x0600 ; top-of-stack

.text ; code Section;**********************************************************************; Start of program...reset: mov.w #STACK,SP ; initialize SP

call #init_MSP430 ; init MSP430call #init_variables ; init variables

;**********************************************************************; Main event loop...loop: call #update_LEDs ; update LED's

call #goto_sleep ; go to sleepcall #adjust_volume ; awake! adjust volumecall #debounce_switch ; debounce switchesjmp loop ; go back to sleep

init_MSP430: ; init MSP430

init_variables: ; init variablesgoto_sleep: ; enter LPM0adjust_volume: ; adjust volumeupdate_LEDs: ; show volume in LEDxdebounce_switch: ; debounce switches

ret

.sect ".reset" ; reset vector section

.word reset ; reset vector ISR 

.end 

Working Program!

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Step 2: Initialize MSP430

Tone Scale Example

  WDT_CLK .set 8000 ; 8 khz clock (@1 Mhz)  WDT_CTL .set WDT_MDLY_8 ; WDT SMCLK, 8 ms;**********************************************************************; Initialize MSP430 routineinit_MSP430:

  mov.w #WDT_CTL,&WDTCTL ; configure WDT

  bic.b #0x03,&P1SEL ; eZ430 LED's  bis.b #0x03,&P1DIR ; P1.0-1 as output  bic.b #0x01,&P1OUT ; turn off red   bis.b #0x02,&P1OUT ; turn on green

  bic.b #0xc0,&P2SEL ; eZ430X LED's  bis.b #0xc0,&P2DIR ; LED #1 & #2  bis.b #0x08,&P3DIR ; LED #3  bis.b #0x40,&P4DIR ; LED #4

  bic.b #0x0f,&P2SEL ; eZ430X push buttons

  bic.b #0x0f,&P2DIR ; P2.0-3 as inputs  bis.b #0x0f,&P2OUT ; P2.0-3 pull-ups  bis.b #0x0f,&P2IES ; h to l  bis.b #0x0f,&P2REN ; enable pull-ups

  bis.b #0x20,&P4DIR ; P4.5 transducer output

clr.w &TBR ; Timer B SMCLK, /1, up mode  mov.w #TBSSEL_2+ID_0+MC_1,&TBCTLret

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 Add WDT 1 second data variable

 Add WDT ISR and interrupt vector 

Tone Scale Example

;**********************************************************************; Watchdog Timer ISR   WDT_ISR: ; WD timer ISR 

dec.w &WDTSecCnt ; 1 second?jne WD10 ; n

xor.b #0x03,&P1OUT ; y, toggle LEDs  mov.w #WDT_CPS,&WDTSecCnt ; reset counter

; <<add scale sequence code here>> 

  WD10: reti ; return from interrupt

;**********************************************************************; Interrupt Vector Table Entries

.sect ".int10" ; WDT vector

.word WDT_ISR ; address of WDT ISR 

.bss WDTSecCnt,2 ; WDT second counter

Step 3a: Implement Watchdog

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Initialize 1 second data variable

Enable interrupts

Tone Scale Example

  myCLOCK .set 1200000 ; 1.2 Mhz clock  WDT_CLK .set 8000 ; 8 khz clock (@1 Mhz)  WDT_CTL .set WDT_MDLY_8 ; WDT SMCLK, 8 ms  WDT_CPS .set myCLOCK/WDT_CLK ; WD clocks / second count

;**********************************************************************; Initalize variables routineinit_variables: ; init variables

  mov.w #WDT_CPS,&WDTSecCnt ; WDT counts/second   bis.b #WDTIE,&IE1 ; enable WDT interruptret

Step 3b: Implement Watchdog

;**********************************************************************; Goto sleep routine (Enable interrupts and LPM0)goto_sleep: ; enter LPM0

  bis.b #LPM0+GIE,SR ; enter LPM0 w/interruptsret

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 Add some tone constants equates

Create melodic array of tone values

Tone Scale Example

; chromatic scale (12 just intonation intervals)DO .set myCLOCK*1000/261626 ; C (261.626 Hz)RE .set DO*8/9 ; D  MI .set DO*4/5 ; EFA .set DO*3/4 ; F

SOL .set DO*2/3 ; GLA .set DO*3/5 ; A TI .set DO*8/15 ; BDO1 .set DO*1/2 ; C

Step 4a: Create Tones

.text ; code Sectionscale .word DO, RE, MI, FA, SOL, LA, TI, DO1

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Create tone index variable

Initialize tone variable in init variable subroutine

Use WDT ISR to sequence thru the scale

Tone Scale Example

Step 4b: Create Tones

  push r4 ; save r4  mov.w &tone,r4 ; get tone

add.w #1,r4 ; next tonecmp.w #MAX_TONE,r4 ; restart scale?jlo WD02 ; n

clr.w r4 ; y

  WD02: mov.w r4,&tone ; save tone; << later adjust tone & volume here >> 

  pop r4

.bss tone,2 ; tone number (0-8)

  MAX_TONE .set 8 ; 0-8 tones  mov.w #0,&tone ; 1st tone

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 Add TimerB ISR and interrupt vector 

 And start TimerB with 1st

tone in init variables subroutine

Tone Scale Example

;**********************************************************************; Timer B ISR TB_ISR: ; timer B ISR 

  bic.w #TBIFG,&TBCTL ; acknowledge interruptxor.b #0x20,&P4OUT ; pulse buzzer

TB04: reti ; return from interrupt

.sect ".int12" ; timer B section

.word TB_ISR ; timer B ISR 

Step 5: Output Tone

  mov.w #DO/2,&TBCCR0 ; start timer clock w/1st note  bis.w #TBIE,&TBCTL ; enable timer B interrupts

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 Add Port 2 ISR to clear LPM0 and enter AM

 And change to LPM0 when enabling interrupts

Tone Scale Example

Step 6: Enter LPM0

;**********************************************************************; Port 2 (switches) ISR P2_ISR: ; Port 2 (switches) ISR 

  bic.b #0x0f,&P2IE ; disable P2 interrupts  bic.w #LPM0,0(SP) ; clear LPM0 from TOS

reti ; return from interrupt

.sect ".int03" ; P2 interrupt vector

.word P2_ISR ; address of Port 2 ISR 

;**********************************************************************; Goto sleep routine (Enable interrupts and LPM0)goto_sleep: ; enter LPM0

  bic.b #GIE,SR ; disable all interruptsclr.b &P2IFG ; acknowledge all  bis.b #0x0f,&P2IE ; enable switch interrupts  bis.b #LPM0+GIE,SR ; enter LPM0 w/interruptsret

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 Add toggle, high, and low duty cycle variables

Use Watchdog interrupt to change tone

Tone Scale Example

Step 7a: Play Scale

.bss duty_cycle_high,2 ; high part of cycle

.bss duty_cycle_low,2 ; low part of cycle

.bss duty_cycle_toggle,1 ; duty cycle flag

; << adjust timer b tone here >>   push r5 ; save r5add.w r4,r4 ; (word index)  mov.w scale(r4),r4 ; r4 = tone (frequency)

; << adjust volume here >> 

rra.w r4 ; 50% duty cycle  mov.w r4,r5

; update tone duty cycle  mov.w r4,&TBCCR0 ; start clock (if necessary)  mov.w r4,&duty_cycle_high ; set high duty cycle  mov.w r5,&duty_cycle_low ; set low duty cycle  pop r5

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Initialize high and low duty cycle variables

 And add high and low duty cycles to Timer_B ISR

Tone Scale Example

Step 7b: Play Scale

;**********************************************************************; Timer B ISR TB_ISR: ; timer B ISR 

  bic.w #TBIFG,&TBCTL ; acknowledge interruptxor.b #0x20,&P4OUT ; pulse buzzerxor.b #0xff,&duty_cycle_toggle ; high?

jeq TB02 ; n mov.w &duty_cycle_high,&TBCCR0 ; y, set high duty cyclejmp TB04

TB02: mov.w &duty_cycle_low,&TBCCR0 ; set low duty cycle

TB04: reti ; return from interrupt

clr.b &duty_cycle_toggle ; init toggle variable  mov.w #DO/2,&duty_cycle_high ; w/1st tone  mov.w #DO/2,&duty_cycle_low

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Create volume index variable to data section

Initialize volume in init_variables

Create a PWM array of duty-cycles in text section

Tone Scale Example

Step 8a: Add Volume

  MAX_VOLUME .set 4 ; 0-4 volume

  mov.w #MAX_VOLUME,&volume ; init volume

; duty cycle table (shift right until duty=0)duty .word 0x7fff, 0x0020, 0x0010, 0x0004, 0x0001; off 3.125% 6.25% 12.5% 50%

.bss volume,2 ; volume (0-8)

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Change Watchdog ISR to use duty array

Tone Scale Example

Step 8b: Add Volume

; << adjust volume here >> ; rra.w r4 ; 50% duty cycle; mov.w r4,r5

  push r6

  mov.w r4,r5 ; save in r5  mov.w volume,r6 ; get volumeadd.w r6,r6 ; (word index)  mov.w duty(r6),r6 ; r6 = duty cycle

  WD04: rra.w r4 ; 1/2 duty cycle, off?jne WD06 ; n

clr.w r5 ; y

  WD06: rra.w r6 ; done?jne WD04 ; n

sub.w r4,r5 ; y, r4+r5=frequency  pop r6

; update tone duty cycle

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Use P2IFG determine which switch was pressed and

adjust volume accordingly

Tone Scale Example

Step 9: Switches Change Volume

;**********************************************************************; Adjust volume routineadjust_volume: ; adjust volume

  bit.b #0x01,&P2IFG ; switch #1?jeq adj02 ; n

sub.w #1,&volume ; y, down volume, too low?jge adj04 ; n

clr.w &volume ; y, clearjmp adj04

adj02: bit.b #0x02,&P2IFG ; switch #2?

jeq adj04 ; nadd.w #1,&volume ; y, turn up volumecmp.w #MAX_VOLUME,&volume ; too high?jlo adj04 ; n

  mov.w #MAX_VOLUME,&volume ; y, set to max

adj04: ret

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Display the current volume setting using 4 LEDs

Tone Scale Example

Step 10: Volume in LEDs

;**********************************************************************; Update LEDs routineupdate_LEDs: ; show volume in LEDs

  bic.b #0xc0,&P2OUT ; LED #1 & #2

  bic.b #0x08,&P3OUT ; LED #3  bic.b #0x40,&P4OUT ; LED #4cmp.w #0,&volumejeq upd02

  bis.b #0x40,&P2OUT ; turn on LED #1cmp.w #1,&volumejeq upd02

  bis.b #0x80,&P2OUT ; turn on LED #2

cmp.w #2,&volumejeq upd02  bis.b #0x08,&P3OUT ; turn on LED #3cmp.w #3,&volumejeq upd02

  bis.b #0x40,&P4OUT ; turn on LED #4

upd02: ret

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Finally, debounce switches (1¶s (up) for 10 ms)

Tone Scale Example

Step 11: Debounce Switches

;**********************************************************************; Switch debounce routine;DB_TIME .set 10 ; 10 ms debounce timeDB_CYCS .set 12 ; instruction cycles for delayDB_DELAY .set DB_TIME*myCLOCK/DB_CYCS/1000 ; delay count

debounce_switch:  push r15 ; callee save

deb02: mov.b &P2IN,r12 ; read switchesxor.b #0x0f,r12 ; SW1-4and.b #0x0f,r12 ; any switch low?

jne deb02 ; y, wait until all off

deb04: mov.w #DB_DELAY,r15 ; minimum delay

deb06: mov.b &P2IN,r12 ; read switchesxor.b #0x0f,r12 ; SW1-4and.b #0x0f,r12 ; all switches high?

jeq deb04 ; n, restart delaydec.w r15 ; y, long enough delay?

jne deb06 ; n, keep going  pop r15 ; y, switches debounced ret

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First, eliminate a lot of code!!

Step 12a: Use Timer Output PWM

.bss duty_cycle_high,2 ; high part of cycle

.bss duty_cycle_low,2 ; low part of cycle

.bss duty_cycle_toggle,1 ; duty cycle flag

  mov.w #DO/2,&TBCCR0 ; start clock  bis.w #TBIE,&TBCTL ; enable timer B interrupts  mov.w #DO/2,&duty_cycle_high ; set duty cycles  mov.w #DO/2,&duty_cycle_low

; << adjust volume here >> ; rra.w r4 ; 50% duty cycle; mov.w r4,r5

  mov.b volume,r5 ; get volume  mov.w duty(r5),r5 ; r5 = duty cyclesub.w r5,r4 ; subtract from frequencycmp.w #0,r5 ; turn off?jne WD04 ; n

  mov.w #0,r4 ; y, high=low=0

  WD04: mov.w r4,&TBCCR0 ; start clock (if necessary)  mov.w r4,&duty_cycle_high ; set high duty cycle  mov.w r5,&duty_cycle_low ; set low duty cycle

TB_isr: ; timer B ISR   bic.w #TBIFG,&TBCTL ; acknowledge interruptxor.b #0x20,&P4OUT ; pulse buzzerxor.b #1,&duty_cycle_toggle ; high?jeq TB02 ; n

  mov.w &duty_cycle_high,&TBCCR0 ; y, set high duty cyclejmp TB04

TB02: mov.w &duty_cycle_low,&TBCCR0 ; set low duty cycle

TB04: reti ; return from interrupt

.sect ".int12" ; timer B section

.word TB_isr ; timer B isr

Pulse Width Modulation (H /W)

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Put transducer (P4.5) as secondary function

Change WD ISR to just put the duty cycle in TBCCR2

Step 12b: Use Timer Output PWM

  bis.b #0x20,&P4SEL ; P4.5 transducer output  mov.w #OUTMOD_3,&TBCCTL2 ; output mode = set/reset  mov.w #DO/2,&TBCCR2 ; use TBCCR2 as volume

; << adjust timer b tone here >>   push r5 ; save r5add.w r4,r4 ; (word index)  mov.w scale(r4),r4 ; r4 = tone (frequency)  mov.w r4,&TBCCR0 ; start clock (if necessary)  mov.b volume,r5 ; get volumeadd.w r5,r5 ; (word index)  mov.w duty(r5),r5 ; r5 = duty cycle  mov.w r5,&TBCCR2 ; start clock (if necessary)  pop r5

Pulse Width Modulation (H /W)

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Example 8: H /W PWM w/Timer_B

Timer B output used to modulate transducer at 440 Hz

.cdecls C,LIST,"msp430x22x4.h"SMCLK .set 1200000 ; 1200000 clocks / second TIME_A3 .set 1000000/440/2/2 ; A = 440 Hz (2x)TB_CTL .set TBSSEL_2+ID_0+MC_1 ; SMCLK,/1,UP (No interrupts)TB_FREQ .set SMCLK/TIME_A3 ; clocks / 440 Hz

reset: mov.w #0x0600,SP ; initialize SP mov.w #WDTPW+WDTHOLD,&WDTCTL ; stop WDT  bis.b #0x20,&P4DIR ; P4.5 transducer output  bis.b #0x20,&P4SEL ; P4.5 timerB outputclr.w &TBR ; reset timerB  mov.w #TB_CTL,&TBCTL ; set timerB control reg  mov.w #OUTMOD_3,&TBCCTL2 ; TB2 output mode = set/reset

  mov.w #TB_FREQ,&TBCCR0 ; set interval (frequency)  mov.w #TB_FREQ/2,&TBCCR2 ; load volume (duty cycle)  bis.w #LPM0+GIE,SR ; enter LPM0 w/interruptsjmp $ ; will never get here!

.sect ".reset" ; reset vector section

.word reset ; reset vector ISR 

.end 

Pulse Width Modulation (H /W)

Set P4.5 asoutput from

TB2

UP mode, TB2 set/reset

50% DutyCycle

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Example 9: H /W PWM w/Timer_A 

#include "msp430x22x4.h"#include <stdio.h> #include "eZ430X.h"#include "lcd.h"#include "adc.h"

void main(void){

eZ430X_init(CALDCO_8MHZ); // init board   ADC_init(); // init ADC

lcd_init(); // init LCD

P2DIR |= 0x10; // P2.4 speaker outputP2SEL |= 0x10; // P2.4 TA2 outputTAR = 0; // reset timer A TACTL = TASSEL_2 + ID_2 + MC_1; // SMCLK, /4, UP (no interrupts)TACCTL2 = OUTMOD_3; // TA2 = set/reset

 while (1)

{ uint16 freq = (1023 - ADC_read(LEFT_POT)) << 6;uint16 duty = ((long)freq * (1023 - ADC_read(RIGHT_POT)) >> 10;TACCR0 = freq; // frequencyTACCR2 = duty; // duty cyclelcd_cursor(10, 4);lcd_printf("Freq:%u ", freq);lcd_cursor(10, 2);lcd_printf("Duty:%u ", duty);

}} // end main

Pulse Width Modulation (H /W)

Set P2.4 asoutput from

TA2

Freq = Left PotDuty Cycle = Right Pot

SMCLK,1 /4,

UP mode, TA2 set/reset

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Example 9: H /W PWM w/Timer_A 

#include "msp430x22x4.h"#include <stdio.h> #include "eZ430X.h"#include "lcd.h"#include "adc.h"

void main(void){

eZ430X_init(CALDCO_8MHZ); // init board   ADC_init(); // init ADClcd_init(); // init LCD

P2DIR |= 0x10; // P2.4 speaker outputP2SEL |= 0x10; // P2.4 TA2 outputTAR = 0; // reset timer A TACTL = TASSEL_2 + ID_2 + MC_1; // SMCLK, /4, UP (no interrupts)TACCTL2 = OUTMOD_3; // TA2 = set/reset

 while (1)

{uint16 freq = (1023 - ADC_read(LEFT_POT)) << 6;uint16 duty = ((long)freq * (1023 - ADC_read(RIGHT_POT)) >> 10;TACCR0 = freq; // frequencyTACCR2 = duty; // duty cyclelcd_cursor(10, 4);lcd_printf("Duty/Freq:%u/%u ", duty, freq);

}} // end main

Pulse Width Modulation (H /W)

Set P2.4 asoutput from

TA2

Freq = Left Pot

Duty Cycle = Right Pot

SMCLK,1 /4,

UP mode, TA2 set/reset

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Example: Recursive Line Draw#include <math.h> #include "msp430x20x3.h"#include "eZ430X.h"#include "lcd.h"#include "graphics.h"

void lcd_draw_line(int x0, int y0, int x1, int y1){

if ((abs(x1 - x0) <= 1) && (abs(y1 - y0) <= 1)){

lcd_point(x0, y0, 1);

lcd_point(x1, y1, 1);}else{

int16 newX = ((x0 + x1) / 2);int16 newY = ((y0 + y1) / 2);lcd_draw_line(newX, newY, x1, y1, pen);lcd_draw_line(x0, y0, newX, newY, pen);

}} // end lcd_draw_line

void main(void){float a;eZ430X_init(CALDCO_8MHZ); // init board lcd_init(); // init LCDlcd_FRAM_init(); // clear lcd FRAM memoryfor (a = 0.0; a < 2 * 3.14159; a += 0.1){

lcd_draw_line(80, 50, (int)(cos(a) * 40 + 80), (int)(sin(a) * 40 + 50));}

} // end main

Recursion

Base case:2 pixel line

360r insteps of 0.1r

Draw 2 lines:

Start to mid-pointMid-point to end