In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Indisputable Attitude wrote:

Let's say that I want the ability to do any kind of square wave, either ½, ¾, ¼ duty cycle, of any frequency I want.  It could be for doing a RS232 kind of protocol, or PWM for motor control or whatever.

Could someone on the forum please explain this a bit?  What are the equations I should use?

The way I understand it right now... You take the Oscillator frequency, say 4_000_000 oscillator cycles/second.  Then, since the SX runs at 4 oscillator cycles/ machine cycles, you end up with 1_000_000 machine_cycles/second.

Then, let's say you want a square wave beep at 4_000 audio_cycles/second, so you then must divide the 1_000_000 machine_cycles/second by the 4_000 audio_cycles/second to get 250 machine_cycles/audio_cycle.  

Assuming a duty cycle of 20%, I must then multiply the 250 by .2 to get 50 for my on_time, and then to get my off time, multiply 250 by .8, and get 200.

So, would the pseudo-code look something like this?
[code]
Start

Load 50 into register A
Load 200 into register B

turn on pin

On_Loop
    decsz register A
    goto On_Loop

turn off pin

Off_Loop
     decsz register B
     goto Off_Loop

     goto Start

[/code]

Please tell me if I'm on the right track with this.  This is a major part of understanding the SX, is it not?  

Formula in text:
A=(((Freq Osc)/(Machine_Cycles/Freq_Osc))/(Audio_freq))*(duty_cycle)

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