image

colors.S

@@ -1,5 +1,6 @@
 #include "colors.h"
 
+#define DIMM_FACTOR 3
   .section ".rodata","a"
 ;; color definitions according to
 ;; https://learn.sparkfun.com/tutorials/lilypad-protosnap-plus-activity-guide/3-custom-color-mixing
@@ -9,29 +10,29 @@ colors:
 off:
   .byte   0x00, 0x00, 0x00, 0
 blue:
-  .byte   0x00, 0x00, 0xff, 0
+  .byte   0x00>>DIMM_FACTOR, 0x00>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0
 green:
-  .byte   0x00, 0xff, 0x00, 0
+  .byte   0x00>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0x00>>DIMM_FACTOR, 0
 orange:
-  .byte   0xff, 0x80, 0x00, 0
+  .byte   0xff>>DIMM_FACTOR, 0x80>>DIMM_FACTOR, 0x00>>DIMM_FACTOR, 0
 rose:
-  .byte   0xff, 0x00, 0x80, 0
+  .byte   0xff>>DIMM_FACTOR, 0x00>>DIMM_FACTOR, 0x80>>DIMM_FACTOR, 0
 magenta:
-  .byte   0xff, 0x00, 0xff, 0
+  .byte   0xff>>DIMM_FACTOR, 0x00>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0
 violet:
-  .byte   0x80, 0x00, 0xff, 0
+  .byte   0x80>>DIMM_FACTOR, 0x00>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0
 azure:
-  .byte   0x00, 0x80, 0xff, 0
+  .byte   0x00>>DIMM_FACTOR, 0x80>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0
 cyan:
-  .byte   0x00, 0xff, 0xff, 0
+  .byte   0x00>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0
 springgreen:
-  .byte   0x00, 0xff, 0x80, 0
+  .byte   0x00>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0x80>>DIMM_FACTOR, 0
 chartreuse:
-  .byte   0x80, 0xff, 0x00, 0
+  .byte   0x80>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0x00>>DIMM_FACTOR, 0
 yellow:
-  .byte   0xff, 0xff, 0x00, 0
+  .byte   0xff>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0x00>>DIMM_FACTOR, 0
 white:
-  .byte   0xff, 0xff, 0xff, 0
+  .byte   0xff>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0xff>>DIMM_FACTOR, 0
 red:
-  .byte   0xff, 0x00, 0x00, 0
+  .byte   0xff>>DIMM_FACTOR, 0x00>>DIMM_FACTOR, 0x00>>DIMM_FACTOR, 0
 

main.S

@@ -50,10 +50,16 @@
   .macro clear_debug
   bic   #BIT2, &P1OUT
   .endm
+  .macro set_signal_waiting_for_data
+  bis   #BIT3, &P1OUT
+  .endm
+  .macro clear_signal_waiting_for_data
+  bic   #BIT3, &P1OUT
+  .endm
 
   .section ".data"
 screendata:
-  .rept 60
+  .rept 60 ;; number of leds in hardward
   .byte 0
   .endr
 screendataend:
@@ -87,8 +93,14 @@ init:
   ;; BIT0: data bit
   ;; BIT1: output enable
   ;; BIT2: debug
-  mov.b   #BIT0|BIT1|BIT2,&P1DIR
+  ;; BIT3: Signal waiting for data
+  mov.b   #BIT0|BIT1|BIT2|BIT3, &P1DIR
   mov.b   #0,&P1OUT
+  ;; BIT5: spi, UCB0CLK
+  ;; BIT6: spi, UCB0SOMI
+  ;; BIT7: spi, UCB0SIMO
+  mov.b   #BIT5|BIT6|BIT7, &P1SEL
+  mov.b   #BIT5|BIT6|BIT7, &P1SEL2
   ;; BIT4: long pulse
   ;; BIT1: short pulse
   mov.b   #BIT1|BIT4,&P2DIR
@@ -108,6 +120,11 @@ init:
   mov.w   #OUTMOD_7,&TA1CCTL1
   mov.w   #OUTMOD_7,&TA1CCTL2
 
+  ;; spi configuration
+  ;;  USCI B to slave mode
+  mov.b   #UCSYNC, &UCB0CTL0
+  mov.b   #0x00, &UCB0CTL1
+
   ;; make sure the isr will not immediately start
   mov.b   #SIGNAL_INIT_VALUE, SIGNAL_REGISTER
 
@@ -124,9 +141,16 @@ mainloop:
 
 mainloop_draw:
   call    #drawscreen
-  call    #forwardscreen
 
-  call    #wait
+  ;; signal waiting for data
+  set_signal_waiting_for_data
+
+  ;call    #forwardscreen
+  ;call    #wait
+  call    #receivedata
+
+  ;; data has been received, clear signal
+  clear_signal_waiting_for_data
 
   jmp     mainloop_draw
 
@@ -164,7 +188,7 @@ forwardscreen:
   mov.w   data_forward_pointer, r10
   mov.b   #_off, @r10
   inc.w   r10
-  mov.b   #_green, @r10
+  mov.b   #_blue, @r10
   cmp.w   r10, r8
   jnz     forwardscreen_done
   mov.w   #screendata, r10
@@ -195,6 +219,50 @@ resetscreen_continue:
   ret
 
 
+;; ----------------------------------------------------
+receivedata:
+  push    r9
+  push    r10
+
+  ;; wait for first octet
+receivedata_wait_for_control_octet:
+  bit     #UCB0RXIFG, &UC0IFG
+  jz      receivedata_wait_for_control_octet
+
+  ;; get control or address octet from buffer register
+  mov.b   UCB0RXBUF, r9
+  ;; check whether value == 0xff (wait for the whole
+  ;; set of data to fill the screendata)
+  cmp.b   #0xff, r9
+  ;; receive all data
+  jz      receivedata_wait_for_all_data
+  ;; check whether value == 0xfe (no more data)
+  cmp.b   #0xfe, r9
+  ;; no more data
+  jz      receivedata_end
+
+  ;; it is an address octet
+receivedata_wait_for_octet:
+  bit     #UCB0RXIFG, &UC0IFG
+  jz      receivedata_wait_for_octet
+
+  ;; get data octet from buffer register
+  mov.b   UCB0RXBUF, r10
+  ;; move it to the destination
+  mov.b   r10, screendata(r9)
+  ;; next address/control octet
+  jmp     receivedata_wait_for_control_octet
+
+receivedata_wait_for_all_data:
+  ;; this is a bit dangerous, if the application controller
+  ;; sends too few data, we are in a dead lock
+
+receivedata_end:
+  pop     r10
+  pop     r9
+  ret
+
+
 ;; ----------------------------------------------------
 drawscreen:
   push    r7

readme.md

@@ -61,3 +61,37 @@ During of loading data into six LEDs: 297us
 | 100       |                    | 5.9ms      |
 | 200       |                    | 11.8ms     |
 
+
+## Reset Circuitry
+
+It appears that the output voltage of the power supply raises that slow, that the MCU
+will not handle the reset correctly.
+
+The following circuitry should generate a valid reset signal far enough from the raise 
+of the supply voltage:
+
+![](./docs/reset-circuit.jpeg)
+
+The circuit generates the following signals:
+
+![](./docs/reset-signal.png)
+
+#### Reference voltage (green):
+
+```math
+U_ref = 3.3V \frac{22k\Omega}{22k\Omega + 10k\Omega} = 2.2V
+```  
+  
+
+#### Trigger voltage (purple):
+
+```math
+U_trigg = 3.3V \frac{330k\Omega}{330k\Omega + 82k\Omega} = 2.64V
+```  
+  
+
+#### RC constant:
+
+```math
+\tau = 82k\Omega \cdot 100nF = 8.2ms
+```