From 77b185831178029b114329116a8dda01ac40755f Mon Sep 17 00:00:00 2001
From: giomba <giomba@glgprograms.it>
Date: Sat, 3 Jul 2021 12:05:49 +0200
Subject: [PATCH] using a prescaler (eg /64) may lead to horizontal offset
 errors

because 1cycle off actually means many cycles off (eg 64)
---
 const.h |  2 +-
 main.S  | 11 ++++-------
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/const.h b/const.h
index b961f5c..fe2112f 100644
--- a/const.h
+++ b/const.h
@@ -1,4 +1,4 @@
 #pragma once
 
 #define VERTICAL_OFFSET 30
-#define HORIZONTAL_OFFSET 3
+#define HORIZONTAL_OFFSET 192
diff --git a/main.S b/main.S
index 3106da5..d1dbfe2 100644
--- a/main.S
+++ b/main.S
@@ -32,7 +32,7 @@ main:
 
     ldi r16, 0x02       ; don't connect output pins to timer, CTC[1:0] mode
     sts TCCR0A, r16
-    ldi r16, 0x03       ; CTC[2] mode, prescaler /64
+    ldi r16, 0x01       ; CTC[2] mode, no prescaler
     sts TCCR0B, r16
 
     ; init variables
@@ -112,17 +112,14 @@ int_timer_0:
 
     sbi IO(PORTB), 4
     nop
-    cbi IO(PORTB), 4
     nop
-    sbi IO(PORTB), 4
     nop
-    cbi IO(PORTB), 4
     nop
-    sbi IO(PORTB), 4
     nop
-    cbi IO(PORTB), 4
     nop
-    sbi IO(PORTB), 4
+    nop
+    nop
+    nop
     nop
     cbi IO(PORTB), 4