From 0dede83883d0303d73400667ec04704c9eacc05e Mon Sep 17 00:00:00 2001
From: Bruno Bousquet <b.b45@hotmail.com>
Date: Fri, 19 Jul 2019 16:16:32 -0400
Subject: [PATCH] add constants for prescaler values

---
 speeduino/board_avr2560.ino | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/speeduino/board_avr2560.ino b/speeduino/board_avr2560.ino
index 9210c458..80b081d1 100644
--- a/speeduino/board_avr2560.ino
+++ b/speeduino/board_avr2560.ino
@@ -3,6 +3,13 @@
 #include "globals.h"
 #include "auxiliaries.h"
 
+// Prescaler values for timers 1-3-4-5. Refer to www.instructables.com/files/orig/F3T/TIKL/H3WSA4V7/F3TTIKLH3WSA4V7.jpg
+const uint8_t TIMER_PRESCALER_1 =    ((0<<CS12)|(0<<CS11)|(1<<CS10));
+const uint8_t TIMER_PRESCALER_8 =    ((0<<CS12)|(1<<CS11)|(0<<CS10));
+const uint8_t TIMER_PRESCALER_64 =   ((0<<CS12)|(1<<CS11)|(1<<CS10));
+const uint8_t TIMER_PRESCALER_256 =  ((1<<CS12)|(0<<CS11)|(0<<CS10));
+const uint8_t TIMER_PRESCALER_1024 = ((1<<CS12)|(0<<CS11)|(1<<CS10));
+
 void initBoard()
 {
     /*
@@ -19,7 +26,7 @@ void initBoard()
     TCCR1B = 0x00;          //Disbale Timer1 while we set it up
     TCNT1  = 0;             //Reset Timer Count
     TCCR1A = 0x00;          //Timer1 Control Reg A: Wave Gen Mode normal (Simply counts up from 0 to 65535 (16-bit int)
-    TCCR1B = (1 << CS12);   //Timer1 Control Reg B: Timer Prescaler set to 256. 1 tick = 16uS. Refer to www.instructables.com/files/orig/F3T/TIKL/H3WSA4V7/F3TTIKLH3WSA4V7.jpg
+    TCCR1B = TIMER_PRESCALER_256;   //Timer1 Control Reg B: Timer Prescaler set to 256. 1 tick = 16uS.
     TIFR1 = (1 << OCF1A) | (1<<OCF1B) | (1<<OCF1C) | (1<<TOV1) | (1<<ICF1); //Clear the compare flags, overflow flag and external input flag bits
 
     boost_pwm_max_count = 1000000L / (16 * configPage6.boostFreq * 2); //Converts the frequency in Hz to the number of ticks (at 16uS) it takes to complete 1 cycle. The x2 is there because the frequency is stored at half value (in a byte) to allow freqneucies up to 511Hz
@@ -35,8 +42,7 @@ void initBoard()
     TIMSK2 = 0x01;          //Timer2 Set Overflow Interrupt enabled.
     TCCR2A = 0x00;          //Timer2 Control Reg A: Wave Gen Mode normal
     /* Now configure the prescaler to CPU clock divided by 128 = 125Khz */
-    TCCR2B |= (1<<CS22)  | (1<<CS20); // Set bits
-    TCCR2B &= ~(1<<CS21);             // Clear bit. Shouldn't be needed as initial value is 0 anyway, but best to play it safe
+    TCCR2B = (1<<CS22)  | (1<<CS20); // Set bits. This timer uses different prescaler values, thus we cannot use the defines above.
     TIFR2 = (1 << OCF2A) | (1<<OCF2B) | (1<<TOV2); //Clear the compare flag bits and overflow flag bit
 
     //Enable the watchdog timer for 2 second resets (Good reference: www.tushev.org/articles/arduino/5/arduino-and-watchdog-timer)
@@ -52,14 +58,14 @@ void initBoard()
     TCCR3B = 0x00;          //Disable Timer3 while we set it up
     TCNT3  = 0;             //Reset Timer Count
     TCCR3A = 0x00;          //Timer3 Control Reg A: Wave Gen Mode normal
-    TCCR3B = (1 << CS11) | (1 << CS10);   //Same as: 0x03. Timer3 Control Reg B: Timer Prescaler set to 256. Refer to www.instructables.com/files/orig/F3T/TIKL/H3WSA4V7/F3TTIKLH3WSA4V7.jpg
+    TCCR3B = TIMER_PRESCALER_64;   //Timer3 Control Reg B: Timer Prescaler set to 64.
     TIFR3 = (1 << OCF3A) | (1<<OCF3B) | (1<<OCF3C) | (1<<TOV3) | (1<<ICF3); //Clear the compare flags, overflow flag and external input flag bits
 
     //Ignition Schedules, which uses timer 5. This is also used by the fast version of micros(). If the speed of this timer is changed from 4uS ticks, that MUST be changed as well. See globals.h and timers.ino
     TCCR5B = 0x00;          //Disable Timer5 while we set it up
     TCNT5  = 0;             //Reset Timer Count
     TCCR5A = 0x00;          //Timer5 Control Reg A: Wave Gen Mode normal
-    TCCR5B = (1 << CS11) | (1 << CS10); //Timer5 Control Reg B: Timer Prescaler set to 64. Refer to www.instructables.com/files/orig/F3T/TIKL/H3WSA4V7/F3TTIKLH3WSA4V7.jpg
+    TCCR5B = TIMER_PRESCALER_64; //Timer5 Control Reg B: Timer Prescaler set to 64.
     TIFR5 = (1 << OCF5A) | (1<<OCF5B) | (1<<OCF5C) | (1<<TOV5) | (1<<ICF5); //Clear the compare flags, overflow flag and external input flag bits
     
     #if defined(TIMER5_MICROS)
@@ -71,7 +77,7 @@ void initBoard()
     TCCR4B = 0x00;          //Disable Timer4 while we set it up
     TCNT4  = 0;             //Reset Timer Count
     TCCR4A = 0x00;          //Timer4 Control Reg A: Wave Gen Mode normal
-    TCCR4B = (1 << CS11) | (1 << CS10);   //Timer4 Control Reg B: aka Divisor = 256 = 122.5HzTimer Prescaler set to 256. Refer to www.instructables.com/files/orig/F3T/TIKL/H3WSA4V7/F3TTIKLH3WSA4V7.jpg
+    TCCR4B = TIMER_PRESCALER_64;   //Timer4 Control Reg B: Timer Prescaler set to 64.
     TIFR4 = (1 << OCF4A) | (1<<OCF4B) | (1<<OCF4C) | (1<<TOV4) | (1<<ICF4); //Clear the compare flags, overflow flag and external input flag bits
 
 }