seems to work so far

Makefile

@@ -4,7 +4,7 @@ OBJDUMP=$(TOOLCHAIN_PREFIX)/bin/msp430-elf-objdump
 
 MCU=msp430g2553
 ARTIFACT=firmware
-COMMON=-Wall -mmcu=$(MCU) -std=gnu99 -I $(TOOLCHAIN_PREFIX)/include -Os -g0 -fdata-sections -ffunction-sections
+COMMON=-Wall -mmcu=$(MCU) -std=gnu99 -I $(TOOLCHAIN_PREFIX)/include -Os -g0 -fdata-sections -ffunction-sections -ggdb -gdwarf-2
 CFLAGS=$(COMMON)
 ASFLAGS=$(COMMON) -D__ASSEMBLER__
 
@@ -33,4 +33,3 @@ clean:
 upload: $(ARTIFACT).elf
 	mspdebug rf2500 "prog $(ARTIFACT).elf"
 
-

main.S

@@ -9,10 +9,13 @@
 
 
   .section ".rodata","a"
-screendatacnt:
-  .byte   0x01
 screendata:
   .byte   0x00
+  .byte   0x01
+  .byte   0x02
+  .byte   0x03
+screendataend:
+  .byte   0xff
 red:
 colors1:
   .byte   0b01001111
@@ -51,6 +54,9 @@ _start:
   ;; initialize stack pointer with value from linker
   mov.w   #__stack, SP
 
+  mov.w   #0xaaaa, r7
+  mov.w   #0x5555, r8
+
 init:
   ;; configuration of GPIO Ports
   mov.b   #BIT0|BIT1|BIT2,&P1DIR
@@ -71,22 +77,37 @@ init:
   mov.w   #OUTMOD_7,&TA1CCTL1
   mov.w   #OUTMOD_7,&TA1CCTL2
 
-  ;; test data
-  mov.b   #0b01101111,r5
   ;; initialize bit-counter for isr
   mov.b   #0x01,r6
   ;; initialize isr-sync register
   mov.b   #0x00,r4
 
+  ;; screen data start/next into r7
+  mov.w   #screendata, r7
+  ;; screen data end into r8
+  mov.w   #screendataend, r8
+  ;; load first screen data value into r5
+  mov.b   @r7,r5
+  inc.w   r7
+
   ;; start timer in up mode
   bis.w   #MC0,&TA1CTL
   ;; enable interrupts
   eint
 
+
+
+
   ;; r4: synchronization between mainloop and isr
   ;; r5: data byte to be handled by isr
 mainloop:
   ;; prepare next byte to handle by isr
+  cmp.w   r7,r8
+  jnz     mainloop_prepare_next_byte
+  mov.w   &screendata,r7
+mainloop_prepare_next_byte:
+  mov.b   @r7,r9
+  inc.w   r7
 
 mainloop_wait_for_isr:
   ;; check bit0 in sync register
@@ -94,7 +115,7 @@ mainloop_wait_for_isr:
   jz      mainloop_wait_for_isr
 
   ;; load data
-  mov.b   #0b01001111,r5
+  mov.b   r9,r5
   mov.b   #0x00,r4
   ;; signal reload
   bis     #BIT2,&P1OUT
@@ -103,6 +124,9 @@ mainloop_wait_for_isr:
   ;; continue
   jmp     mainloop
 
+
+
+
 ; --- timer isr ---
   ;; r6: exclusively used by isr as bit-counter
 timer1_a0_isr:

readme.md

@@ -0,0 +1,5 @@
+mspdebug rf2500 gdb
+msp430-gdb -x firmware.gdb
+
+Attention: the gdb in the TI toolchain package is broken, use the one from Debian
+