MSP430 - skeleton standalone assembler project for msp430-elf-gcc and mspdebug

blinkasm.gdb

target remote localhost:2000
monitor reset
monitor erase
load blinkasm.elf
b
disassemble
nexti
disassemble
nexti
info registers
b timer0_toggle
continue

blinkasm.S

;-------------------------------------------------------------------------------
; blinkasm.S - gcc compatible interrupt driven led blinker in msp430 asm
;
; Version 1.0  - 10/22/2011 rick@kimballsoftware.com
; Version 1.01 -  7/22/2014 rick@kimballsoftware.com modified for msp430-elf-gcc
; Version 1.02 - 11/02/2014 rick@kimballsoftware.com more changes for msp430-elf-gcc
; $ msp430-elf-gcc blinkasm.S -D_GNU_ASSEMBLER_ -Wall -Os -g \
;       -fdata-sections -ffunction-sections -mmcu=msp430g2553 -T \
;       -T msp430g2553.ld -I/tmp/a/include -L /tmp/a/include/ -nostdlib
;       
;-------------------------------------------------------------------------------
        .file "blinkasm.S"
        
#include <msp430.h>

;-------------------------------------------------------------------------------
;;; ---- gcc doesn't know about PC,SP,SR,CG1,CG2 ----

#define PC r0                   
#define SP r1
#define SR r2

;-------------------------------------------------------------------------------
;;; ---- CONSTANTS ----

//#define TEST_IRQ_OVERHEAD

#ifndef TEST_IRQ_OVERHEAD
 #define _50USEC (50-1)   /* @1MHz MCLK results in 50uSec/interrupt */
 #define _500MSEC 10000   /* @1MHz MCLK results in 500ms/LED toggle */
#else
 ;; This test illustrates the minimum CCR0 value that can be used
 ;; 22 cycles is based on the interrupt overhead
 #define _50USEC 22       /* @1MHz MCLK results in 23uSec/interrupt */
 #define _500MSEC 1       /* @1MHz MCLK results in 23uSec/LED toggle */
#endif
#define _LED_PIN BIT6     /* PORT1 pin, Launchpad has BIT0=Red and BIT6=Green */

;-------------------------------------------------------------------------------
;;; ---- Registers used as globals ----

#define LED_PIN r4
#define TIMER_CYCLES r5
#define INTERVAL_CNT r6
#define CNT r7

        ;;  or you could use some ram variables
        .lcomm tcycles,2        ; example use of local bss data variable
        .lcomm cnt,2            ; example use of local bss data variable

;-------------------------------------------------------------------------------
        .section .text,"ax",@progbits
;-------------------------------------------------------------------------------
_start:
        ;; disable watchdog and set stack to highest RAM addr
        mov.w   #WDTPW|WDTHOLD,&WDTCTL
        mov.w   #__stack,SP                     ; gcc ldscripts compute __stack based on mmcu

        ;; initialize clock,gpio,timer
init:
        ;; configure DCO to precalibrated 1MHz
        clr.b   &DCOCTL
        mov.b   &CALBC1_1MHZ,&BCSCTL1
        mov.b   &CALDCO_1MHZ,&DCOCTL

        ;; initialize global register values
        mov.w   #_LED_PIN,LED_PIN               ; load constant into register constant
        mov.w   #_50USEC,TIMER_CYCLES           ; load constant into register constant
        mov.w   #_500MSEC,INTERVAL_CNT          ; load constant into register constant
        mov.w   INTERVAL_CNT,CNT                ; initialize register based counter

        ;; initialize GPIO
        bic.b   LED_PIN,&P1OUT                  ; LED turned off to start
        bis.b   LED_PIN,&P1DIR                  ; Configure P1.0 as output pin

        ;; initialize TimerA0
        mov.w   #CCIE,&TA0CCTL0                 ; Enable TA0CCR0 interrupt
        mov.w   TIMER_CYCLES,&TA0CCR0           ; Set TIMER_CYCLES cycles
        mov.w   #TASSEL_2|MC_2,&TACTL           ; SMCLK, Continuous Up Mode

        ;; enable interrupts and loop forever
        ;; real work done in the CCR0 interrupt
        nop
        eint

loop:
        ;; Note: could sleep here instead
        jmp     loop                            ; cycles:2

;-------------------------------------------------------------------------------
; TIMER0_A0_ISR - TimerA0 CCR0 interrupt handler
;-------------------------------------------------------------------------------
TIMER0_A0_ISR:
        ;;  before we even start running the mcu does a push PC, and a push SR cycles:6
        dec.w   CNT                             ; have we looped INTERVAL_CNT times? cycles:1
        jnz     1f                              ; exit if we haven't reached 0 cycles:2

        ;; toggle led pin after (INTERVAL * TIMER_CYCLES) has occured
        xor.b   LED_PIN,&P1OUT                  ; cycles:4
        mov.w   INTERVAL_CNT,CNT                ; reinitialize interval counter cycles:1
1:
        add.w   TIMER_CYCLES,&TA0CCR0           ; set new CCR0 and go again cycles:4
        reti                                    ; cycles:5

;------------------------------------------------------------------------------
; UNEXPECTED_ISR - default handler for unhandled interrupt
;-------------------------------------------------------------------------------
UNEXPECTED_ISR:
        reti                                    ; cycles: 5

;------------------------------------------------------------------------------
; Interrupt Vectors - see the datasheet for your chip
;                    *msp430g2553 vectors described below
;------------------------------------------------------------------------------
        .section "__interrupt_vector_10","ax",@progbits
        .word TIMER0_A0_ISR     ;0xfff2 (TIMER0_A0_VECTOR)

        .section ".resetvec","ax",@progbits
        .word _start            ;0xfffe (RESET_VECTOR)

        .end

; vim: ts=8 sw=8 expandtab:

Makefile

#
# Makefile - blinkasm.elf
#
# Author: Rick Kimball
# email: rick@kimballsoftware.com
# Version: 1.04 Initial version 10/21/2011
# 

APP = blinkasm
MCU ?= msp430g2553

# MSP430_DEV_IN should be the directory where *.ld and devices.csv are located
MSP430_DEV_INC ?= ${HOME}/opt64/msp430-elf/include

CC=msp430-elf-gcc
CXX=msp430-elf-g++
COMMON=-Wall -Os -g -I./ -I $(MSP430_DEV_INC)
CFLAGS   += -mmcu=$(MCU) $(COMMON)
CXXFLAGS += -mmcu=$(MCU) $(COMMON)
ASFLAGS  += -mmcu=$(MCU) $(COMMON)
LDFLAGS   = -L $(MSP430_DEV_INC) -Wl,-Map,$(APP).map -nostdlib -nostartfiles -T $(MCU).ld

all: $(APP).elf

$(APP).elf: $(APP).o
	$(CC) $(CFLAGS) $(APP).o $(LDFLAGS) -o $(APP).elf
	msp430-elf-objdump -Sd -W $(APP).elf >$(APP).lss
	msp430-elf-size $(APP).elf
	msp430-elf-objcopy -O ihex blinkasm.elf blinkasm.hex

install: all
	mspdebug --force-reset rf2500 "prog $(APP).elf"

cycle_count: all
	naken430util -disasm $(APP).hex > $(APP)_cc.txt

debug: all
	clear
	@echo -e "--------------------------------------------------------------------------------"
	@echo -e "-- Make sure you are running mspdebug in another window                       --"
	@echo -e "--------------------------------------------------------------------------------"
	@echo -e "$$ # you can start it like this:"
	@echo -e "$$ mspdebug rf2500 gdb\n"
	msp430-elf-gdb --command=blinkasm.gdb $(APP).elf

clean:
	rm -f $(APP).o $(APP).elf $(APP).lss $(APP).map $(APP).hex $(APP)_cc.txt