Adjusting PWM Frequencies

by macegr in this forum post http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1235060559/12

How to adjust Arduino PWM frequencies

Pins 5 and 6: controlled by Timer 0

Setting 	Divisor 	Frequency
0x01 	 	1 	 	62500
0x02  		8 	 	7812.5
0x03  		64 	 	976.5625
0x04 	 	256 	 	244.140625
0x05 	 	1024 	 	61.03515625

TCCR0B = TCCR0B & 0b11111000 | <setting>;

Pins 9 and 10: controlled by timer 1

Setting 	Divisor 	Frequency
0x01 	 	1 	 	31250
0x02 	 	8 	 	3906.25
0x03  		64 	 	488.28125
0x04  		256 	 	122.0703125
0x05 	 	1024 	 	30.517578125

TCCR1B = TCCR1B & 0b11111000 | <setting>;

Pins 11 and 3: controlled by timer 2

Setting 	Divisor 	Frequency
0x01 	 	1  		31250
0x02 	 	8 	 	3906.25
0x03  		32  		976.5625
0x04 	 	64 	 	488.28125
0x05 	 	128  		244.140625
0x06  		256  		122.0703125
0x07 	 	1024  		30.517578125

TCCR2B = TCCR2B & 0b11111000 | <setting>;

All frequencies are in Hz and assume a 16000000 Hz system clock.

Issues from adjusting PWM frequencies and workarounds:

from koyaanisqatsi in this forum post http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1235060559/12

If you change TCCR0B, it affects millis() and delay(). They will count time faster or slower than normal if you change the TCCR0B settings. Below is the adjustment factor to maintain consistent behavior of these functions:

Default: delay(1000) or 1000 millis() ~ 1 second

0x01: delay(64000) or 64000 millis() ~ 1 second
0x02: delay(8000) or 8000 millis() ~ 1 second
0x03: is the default
0x04: delay(250) or 250 millis() ~ 1 second
0x05: delay(62) or 62 millis() ~ 1 second
(Or 63 if you need to round up. The number is actually 62.5)

Also, the default settings for the other timers are:
TCCR1B: 0x03
TCCR2B: 0x04

There may be other side effects from changing TCCR0B. For example my project would not properly run with TCCR0B set to 0x02 or 0x01. But it worked fine at 0x03 and higher. YMMV

Any thought on the Arduino Mega?