From: Ben Gamari <bgamari.foss@gmail.com>
Date: Wed, 7 Mar 2012 22:58:35 +0000 (-0500)
Subject: stepper: Clarify comment on timer-counter configuration
X-Git-Tag: iwj-success-2012-07-29~58^2~1
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=96509494f0d0438fc4f85171b66ec2a598f00a62;p=marlin.git

stepper: Clarify comment on timer-counter configuration
---

diff --git a/Marlin/stepper.cpp b/Marlin/stepper.cpp
index 55c0990..c3ea41b 100644
--- a/Marlin/stepper.cpp
+++ b/Marlin/stepper.cpp
@@ -740,7 +740,13 @@ void st_init()
   // output mode = 00 (disconnected)
   TCCR1A &= ~(3<<COM1A0); 
   TCCR1A &= ~(3<<COM1B0); 
-  TCCR1B = (TCCR1B & ~(0x07<<CS10)) | (2<<CS10); // 2MHz timer
+  
+  // Set the timer pre-scaler
+  // Generally we use a divider of 8, resulting in a 2MHz timer
+  // frequency on a 16MHz MCU. If you are going to change this, be
+  // sure to regenerate speed_lookuptable.h with
+  // create_speed_lookuptable.py
+  TCCR1B = (TCCR1B & ~(0x07<<CS10)) | (2<<CS10);
 
   OCR1A = 0x4000;
   TCNT1 = 0;