Add register usage comment

2026-01-09 11:40:24 +01:00
parent 8205c7892a
commit e24c4ee591
1 changed files with 8 additions and 3 deletions
@@ -1,6 +1,11 @@
-; Registers:
-;   r16: timer0 setup (can reuse after ret)
-;   r17: timer1 dynamic setup (always needed)
+; Register usage:
+;   (r1 = 0; r1 = 1)
+;   r16     -> everything related to timer0 and led blinking
+;   r17:r18 -> 16-bit accumulator (r17 = low byte, r18 = high byte)
+;   r19:r20 -> 16-bit BPM target (r19 = low byte, r20 = high byte);
+;
+;   r19 -> quantization; how often the ISR runs (affects: jitter, cpu load)
+;   r21 -> phase resolution (affects: fractional BPM values, error distribution)

 timer0_set:
    out     TCCR0A,     r0                          ; T/C Control Register A enable normal mode