Seven Segment Display Counter

Question

Use the MSP430 seven-segment daughter board (available in the IEEE office) to implement a hexadecimal up-down counter on a single digit of the seven-segment display. The counter should start at 0x0, count up to 0xF, count down to 0x0, and repeat indefinitely. The counter should update every 500ms. Engineering Constraints Your implementation must: • Make use of the timerperipherals. • Utilize a lookup table for the seven-segment values.

I am using the MSP-EXP430FR6989 on an empty assembly only project in TI Code Composer Studio. Here is the code I have.

;-------------------------------------------------------------------------------
; MSP430 Assembler Code Template for use with TI Code Composer Studio
;
;
;-------------------------------------------------------------------------------
            .cdecls C,LIST,"msp430.h"       ; Include device header file
            
;-------------------------------------------------------------------------------
            .def    RESET                   ; Export program entry-point to
                                            ; make it known to linker.
;-------------------------------------------------------------------------------
            .text                           ; Assemble into program memory.
            .retain                         ; Override ELF conditional linking
                                            ; and retain current section.
            .retainrefs                     ; And retain any sections that have
                                            ; references to current section.

;-------------------------------------------------------------------------------
RESET       mov.w   #__STACK_END,SP         ; Initialize stackpointer
StopWDT     mov.w   #WDTPW|WDTHOLD,&WDTCTL  ; Stop watchdog timer
ENIO        clr     PM5CTL0

;-------------------------------------------------------------------------------
; Main loop here
;-------------------------------------------------------------------------------
; Hexadecimal Up-Down Counter for MSP430FR6989 with Seven-Segment Display

; Define registers
COUNTER      .equ  R4               ; Counter variable

; Define constants
DELAY        .equ  50000            ; Delay for debouncing
INCREMENT    .equ  1                ; Increment value for counter

; Seven-segment display patterns for hex digits
SEGMENTS    .word 0x3F00, 0x0600, 0x5B00, 0x4F00, 0x6600, 0x6D00, 0x7D00, 0x0700, 0x7F00, 0x6F00

            .sect   ".text"

            .bss    COUNTER          ; Reserve memory for counter variable

            .text
            nop

start:      mov     #0xA55A, SR      ; Disable watchdog
            nop

            ; Configure GPIO for Seven-Segment Display
            mov     #0xFF00, &P2DIR  ; Set P2.0 to P2.7 as output (assuming the seven-segment display is connected to P1.0 to P1.7)
            mov     #0x0006, &P1OUT  ; Initialize P1.5 to turn off the seven-segment display

            ; Initialize counter
            mov     #0, COUNTER        ; Clear counter


mainLoop:   ; Display counter value on Seven-Segment Display

            ; Check for button press (assuming button connected to P1.3)
            bit.b   #0x04, &P1IN     ; Check P1.3 (Button)
            jz      noButtonPress    ; If button not pressed, skip increment/decrement

            ; Debounce delay
            mov     #DELAY, R5
delayLoop:  dec     R5
            jnz     delayLoop

            ; Check button again after delay for debouncing
            bit.b   #0x04, &P1IN
            jz      noButtonPress

            ; Button pressed, increment or decrement counter
            bit.b   #0x06, &P1IN     ; Check P1.5 (Assuming connected to another button)
            jz      decrementCounter
            inc     COUNTER          ; Increment counter
            jmp     updateDisplay

decrementCounter:
            dec     COUNTER          ; Decrement counter

updateDisplay:
            ; Update Seven-Segment Display based on the counter value
            mov     COUNTER, R6      ; Load counter value into R6
            and     #0x0F, R6        ; Mask higher bits to ensure a single digit

            ; Use R6 as an index to fetch the corresponding seven-segment pattern
            mov.w   SEGMENTS(R6), R7 ; Fetch the pattern

            ; Output the pattern to P2.0 to P2.7
            mov     R7, &P2OUT

noButtonPress:
            jmp     mainLoop         ; Continue looping
            nop

            .end
                                            

;-------------------------------------------------------------------------------
; Stack Pointer definition
;-------------------------------------------------------------------------------
            .global __STACK_END
            .sect   .stack
            
;-------------------------------------------------------------------------------
; Interrupt Vectors
;-------------------------------------------------------------------------------
            .sect   ".reset"                ; MSP430 RESET Vector
            .short  RESET
            

The code I wrote is inside the "Main loop here" section, and everything else comes with the empty assembly only project. Whenever I run the program, I get the following errors: "../main.asm", ERROR! at line 40: [E0005] Operand missing .bss COUNTER ; Reserve memory for counter variable

"../main.asm", ERROR! at EOF: [E0300] The following symbols are undefined: __STACK_END I will attach a picture of the daughter board schematic and pin connections to the MSP430. Daughter board schematic Pin connections