wunderschoen kommentierte version ;)

diff --git a/beginners/test_int.asm b/beginners/test_int.asm
index 6329fcf..ba2317d 100644 (file)
--- a/beginners/test_int.asm
+++ b/beginners/test_int.asm
@@ -1,7 +1,7 @@
 ;
-; portd 3-7 blinken lights ;)
+; portd 3-7 lauflicht mit UART-RX masked byte anzeige
 ;
-; author: hackbard@hackdaworld.dyndns.org
+; by Hunz ;)
 ;
 
 .include "../include/2313def.inc"
@@ -40,42 +40,59 @@ reti
 reti
 
 T1_OVF1:
+; toggle LED
 out DDRD, r17
+; next LED
 rol r17
+; skip next operation if beyond last LED
 sbrs r17, 7
-reti
+reti   ; we return if not beyond last LED
+; reset LED counter to first LED
 ldi r17, 4
 reti
 
 UART_RX:
+; read received byte to r16
 in r16, UDR
+; mask with valid LED bits
 andi r16, $7C
+; echo masked byte
 out UDR, r16
+; set LEDs according to masked byte
 out DDRD, r16
 reti
 
 INIT:
+; Stackpointer setzen
 ldi r16, Low(RAMEND)
 out SPL, r16
 
 ; baudrate einstellen
 ldi r16, 11 ; "38400 bps wert" in r16
 out UBRR, r16 ; write to uart baudrate register
+
+; enable TX, RX, Interrupt on RX
 ldi r16, ((1<<RXEN)|(1<<TXEN)|(1<<RXCIE))
 out UCR, r16
 
+; PortD Inputs - Enable all LEDs
 ldi r16, 0x7C
 out DDRD, r16
 
+; Least Significant LED
 ldi r17, 4
 
+; Timer1 Prescaler: CLK/64 (inc. Timer1 every 64 CLKs)
 ldi r16, 3
 out TCCR1B, r16
 
+; Timer1 Overflow Interrupt enable
 ldi r16, (1<<TOIE1)
 out TIMSK, r16
 
+; global interrupts enable
 sei
 
+; main loop
 MAIN:
 rjmp MAIN