diff --git a/colors.S b/colors.S
index e18aa20..a575272 100644
--- a/colors.S
+++ b/colors.S
@@ -3,9 +3,9 @@
   .section ".rodata","a"
 screendata_tmpl:
   .global screendata_tmpl
-  .byte _off
-  .byte _white
-  .byte _off
+  .byte _blue
+  .byte _green
+  .byte _red
 screendataend_tmpl:
   .byte   0xff
 
diff --git a/main.S b/main.S
index 1659b13..6bd1e64 100644
--- a/main.S
+++ b/main.S
@@ -41,6 +41,12 @@
   .macro clear_output_enable
   bic   #BIT1, &P1OUT
   .endm
+  .macro set_debug
+  bis   #BIT2, &P1OUT
+  .endm
+  .macro clear_debug
+  bic   #BIT2, &P1OUT
+  .endm
 
   .section ".data"
 screendata:
@@ -171,7 +177,7 @@ mainloop_wait_for_isr_2:
 mainloop_data_done:
   ;; signal all data processed, isr finish
   bis     #SIGNAL_ALL_DATA_DONE,  SIGNAL_REGISTER
-  bis     #BIT2, &P1OUT
+  set_debug
   ;; continue
   jmp     mainloop