5: Lab Stoplight Lab
Lab 5: Stoplight
Program an assembly, callee-save, timer subroutine that executes (delays) in variable increments of 1/10 second. Use the timing subroutine to program timing delays for a simple traffic stoplight.
6
Turn on the green LED for 5 seconds. Blink the green LED on and off at 1 second intervals for seconds (3 offs and 3 ons). Blink the green LED on and off at 0.2 second intervals seconds (10 offs and 10 ons).
for 4
And finally, turn the green LED off (and the red LED on) for 10 seconds. The total traffic light cycle time should be 25 seconds (plus or minus 1/2 second).
Repeat the stoplight cycle indefinitely.
BYU CS/ECEn 124 Stoplight Lab 1
Lab 5: Stoplight Lab
Blink the green LED on and off at 1 second intervals for 6 seconds (3 offs and 3 ons).
Lab 5: Stoplight
Turn on the green LED for 5 seconds.
Blink the green LED on and off at 0.2 second intervals for 4 seconds (10 offs and 10 ons).
And finally, turn the green LED off (and the red LED on) for 10 seconds.
ON
5
1
1
1
1
1
1
1
1
1
1
10
OFF
BYU CS/ECEn 124
The total traffic light cycle time should be 25 seconds ( 1/2 second).
Stoplight Lab
2
Stoplight Lab
DELAY RESET: .cdecls C,LIST,"msp430.h" .equ (50/8) .text mov.w mov.w bis.b xor.b call jmp push.w push.w mov.w dec.w jeq mov.w dec.w jnz jmp pop.w pop.w ret #0x0280,SP #WDTPW+WDTHOLD,&WDTCTL #0x01,&P1DIR #0x01,&P1OUT #delay1sec r12 mainloop r15 #DELAY,r12 r12 delay06 #0,r15 r15 delay04 delay02 r15 r12 ; MSP430 ; ; ; ;
Lab 5: Stoplight
beginning of code init stack pointer stop WDT set P1.0 as output
mainloop:
; toggle P1.0
delay1sec:
; callee-save
Save all registers used in subroutine
; get delay count ; done? ; y, return ; n, use R15 as delay counter ; delay over? ; n ; y ;
delay02:
delay04:
delay06:
Restore registers at restore registers end of subroutine
.sect ".reset" .word RESET BYU CS/ECEn 124 .end Stoplight Lab
; MSP430 RESET Vector ; start address 3
Lab 5: Stoplight Lab
Lab 5: Stoplight
2 points All software delays are implemented using a 1/10 second delay assembly subroutine. The subroutine is implemented using a callee-save protocol. 2 points The assembler directive .equ is used to define all delay counts and constants. 4 points Your traffic stoplight machine works as specified. That is, the green LED is on for 5 seconds. The green LED blinks on and off at 1 second intervals for 6 seconds (3 offs and 3 ons). Then the green LED blinks on and off at 0.2 second intervals for 4 seconds (10 offs and 10 ons). And finally, the green LED is turned off (and the red LED on) for 10 seconds. 2 points The total traffic light cycle time is 25 seconds with less than a 1/2 second error. +1 point timing The number of 1/10 second delays is passed to the subroutine on the stack.
Stoplight Lab 4
BYU CS/ECEn 124