Generate 4 Square signals of different frequencies(<35hz) using Mega2560?

Projects Programming
1

Hi,
I would like to generate 4 square waves of different frequencies lets say 6hz, 9.5hz, 15hz, 20hz signals.Till now by referring some posts,I was able to generate 3 square waves(30hz) using timers.Please help me get through this.
Here is the code for timers 2,3 (I am using arduino Mega2560)

void setup() {

TCCR2B = TCCR2B & B11111000 | B00000111; // for PWM frequency of 30.6hz
TCCR3B = TCCR3B & B11111000 | B00000101; // for PWM frequency of 30.6hz

pinMode(9,OUTPUT);
pinMode(10,OUTPUT);
pinMode(2,OUTPUT);

}
void loop() {
analogWrite(9,127);
analogWrite(10,127);
analogWrite(2,127);
}
2

For frequencies that low, you can use millis() and digitalWrite().
Example 20Hz is ON for 25mS and OFF for 25mS (with 50% duty cycle).

3

...and you were told that in your other thread on this topic (micros would be better)

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