rolling led

colors.S

@@ -3,66 +3,66 @@
   .section ".rodata","a"
 screendata_tmpl:
   .global screendata_tmpl
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
-  .byte _green
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
+  .byte _red
 screendataend_tmpl:
   .byte   0xff
 

main.S

@@ -6,19 +6,25 @@
 #define SR r2
 
 
+;; ----------------------------------------------------
+;; --- r4, r5 and r6 must not be used for any other ---
+;; --- purpose                                      ---
+;; required for communication between drawscreen and isr
 #define SIGNAL_REGISTER r4
 #define SIGNAL_OCTET_DONE 0x01
 #define SIGNAL_ISR_ENABLE 0x02
 #define SIGNAL_ALL_DATA_DONE 0x04
+#define SIGNAL_INIT_VALUE SIGNAL_OCTET_DONE
 
-
-#define DATA_NEXT_ADDRESS_REGISTER r7
-#define DATA_END_ADDRESS_REGISTER r8
+;; required for handover of data between drawscreen and isr
 #define DATA_REGISTER r5
-#define NEXT_DATA_REGISTER r9
 
+;; required for sequencing of isr
 #define BIT_COUNTER_REGISTER r6
 #define BIT_COUNTER_INIT_VALUE 0x01
+;; ----------------------------------------------------
+
+
 
 
 
@@ -55,6 +61,8 @@ screendata:
   .endr
 screendataend:
   .byte 0xff
+data_forward_pointer:
+  .word 0
 
 
   ;; .text is the name of the section, it is a hint for the linker to
@@ -76,20 +84,7 @@ _start:
   ;; initialize stack pointer with value from linker
   mov.w   #__stack, SP
 
-  ;; ----------------------------------------------
-  ;; load data from template area in rom into ram
-  ;; uses arbitrary register before loading registers
-  ;; for later use
-  mov.w   #screendata, r7
-  mov.w   #screendataend, r8
-  mov.w   #screendata_tmpl, r9
-_start_load_next:
-  mov.b   @r9, @r7
-  inc.w   r7
-  inc.w   r9
-  cmp.w   r7, r8
-  jnz _start_load_next
-  ;; ----------------------------------------------
+
 
 init:
   ;; configuration of GPIO Ports
@@ -117,6 +112,96 @@ init:
   mov.w   #OUTMOD_7,&TA1CCTL1
   mov.w   #OUTMOD_7,&TA1CCTL2
 
+
+  ;; make sure the isr will not immediately start
+  mov.b   #SIGNAL_INIT_VALUE, SIGNAL_REGISTER
+
+  ;; start timer in up mode
+  bis.w   #MC0,&TA1CTL
+  ;; enable interrupts
+  eint
+
+mainloop:
+  call    #forwardscreen_init
+  call    #resetscreen
+
+mainloop_draw:
+  call    #drawscreen
+  call    #forwardscreen
+
+  call    #wait
+
+  jmp     mainloop_draw
+
+
+wait:
+  push    r11
+  push    r12
+
+  mov.w   #0x0040, r11
+wait_continue_1:
+  mov.w   #0xffff, r12
+wait_continue_2:
+  dec.w   r12
+  jnz     wait_continue_2
+  dec.w   r11
+  jnz     wait_continue_1
+
+  pop     r12
+  pop     r11
+  ret
+
+forwardscreen_init:
+  mov.w   #screendata, &data_forward_pointer
+  ret
+
+forwardscreen:
+  push    r8
+  push    r10
+
+  mov.w   #screendataend, r8
+  mov.w   data_forward_pointer, r10
+  mov.b   #_off, @r10
+  inc.w   r10
+  mov.b   #_red, @r10
+  cmp.w   r10, r8
+  jnz     forwardscreen_done
+  mov.w   #screendata, r10
+forwardscreen_done:
+  mov.w   r10, data_forward_pointer
+
+  pop     r10
+  pop     r8
+  ret
+  
+
+resetscreen:
+  push    r7
+  push    r8
+
+  ;; reset screen data
+  mov.w   #screendata, r7
+  mov.w   #screendataend, r8
+resetscreen_continue:
+  mov.b   #_off, @r7
+  inc.w   r7
+  cmp.w   r7, r8
+  jnz resetscreen_continue
+
+  pop     r8
+  pop     r7
+  ret
+
+
+drawscreen:
+  push    r7
+  push    r8
+  push    r9
+
+#define DATA_NEXT_ADDRESS_REGISTER r7
+#define DATA_END_ADDRESS_REGISTER r8
+#define NEXT_DATA_REGISTER r9
+
   ;; initialize bit-counter for isr
   mov.b   #BIT_COUNTER_INIT_VALUE, BIT_COUNTER_REGISTER
   ;; initialize isr-sync register, signal BYTE_DONE for the first start
@@ -127,15 +212,10 @@ init:
   ;; screen data end into r8
   mov.w   #screendataend, DATA_END_ADDRESS_REGISTER
 
-  ;; start timer in up mode
-  bis.w   #MC0,&TA1CTL
-  ;; enable interrupts
-  eint
-
-mainloop:
+drawscreen_continue:
   ;; prepare next byte to handle by isr
   cmp.w   DATA_NEXT_ADDRESS_REGISTER, DATA_END_ADDRESS_REGISTER
-  jz      mainloop_data_done
+  jz      drawscreen_data_done
 
   ;; load next data byte
   mov.b   @DATA_NEXT_ADDRESS_REGISTER, NEXT_DATA_REGISTER
@@ -148,42 +228,42 @@ mainloop:
   ;; enable isr
   bis     #SIGNAL_ISR_ENABLE, SIGNAL_REGISTER
 
-mainloop_wait_for_isr_0:
+drawscreen_wait_for_isr_0:
   ;; check bit0 in sync register
   bit     #SIGNAL_OCTET_DONE, SIGNAL_REGISTER
-  jz      mainloop_wait_for_isr_0
+  jz      drawscreen_wait_for_isr_0
   ;; load data
   mov.b   colors(NEXT_DATA_REGISTER), DATA_REGISTER
   ;; clear BYTE_DONE
   bic     #SIGNAL_OCTET_DONE,  SIGNAL_REGISTER
-mainloop_wait_for_isr_1:
+drawscreen_wait_for_isr_1:
   ;; check bit0 in sync register
   bit     #SIGNAL_OCTET_DONE, SIGNAL_REGISTER
-  jz      mainloop_wait_for_isr_1
+  jz      drawscreen_wait_for_isr_1
   ;; load data
   mov.b   colors+1(NEXT_DATA_REGISTER), DATA_REGISTER
   ;; clear BYTE_DONE
   bic     #SIGNAL_OCTET_DONE,  SIGNAL_REGISTER
-mainloop_wait_for_isr_2:
+drawscreen_wait_for_isr_2:
   ;; check bit0 in sync register
   bit     #SIGNAL_OCTET_DONE, SIGNAL_REGISTER
-  jz      mainloop_wait_for_isr_2
+  jz      drawscreen_wait_for_isr_2
   ;; load data
   mov.b   colors+2(NEXT_DATA_REGISTER), DATA_REGISTER
   ;; clear BYTE_DONE
   bic     #SIGNAL_OCTET_DONE,  SIGNAL_REGISTER
 
   ;; continue
-  jmp     mainloop
+  jmp     drawscreen_continue
 
-mainloop_data_done:
+drawscreen_data_done:
   ;; signal all data processed, isr finish
   bis     #SIGNAL_ALL_DATA_DONE,  SIGNAL_REGISTER
 
-
-  jmp     mainloop_data_done
-
-
+  pop     r9
+  pop     r8
+  pop     r7
+  ret