I don't understand this code!

[Russ Kincaid]

Thanks, I should have said that: I want the output to be low for the short time (4+ms) and high for the long time (12+ms). I think the program should do that, but it doesn't. The output is high for the short time and low for the long time.

[languer]

Your main code looks fine:

START:
LOW GPIO.1 
PAUSEUS 4168 ' ON TIME
HIGH GPIO.1
PAUSEUS 4167 'DEAD TIME 
LOW GPIO.0 'SETS PIN 7 LOW
PAUSEus 4168 'FOR 4.168 MILLISECONDS 
HIGH GPIO.0
PAUSEUS 4167 'DEAD TIME

Your startup code does not:

TRISIO = %111111

This sets all pins to <U>inputs</U>. You want to use:

TRISIO = %001000 '(since GPIO3 is input only anyway)

[skimask]

TRISIO = %001000 '(since GPIO3 is input only anyway)

Except for the fact that HIGH and LOW automatically set the pins as outputs...

Now then...what is this output thing? Is this a 2 bit R/2R D/A ladder type setup or what is it?

[mister_e]

If it was me, i would use a timer interrupt, but add somes extra filter outside.

I don't understand what you mean by

The program runs but the waveform is upside down. I could change the circuit to accept the upside down wave,

[Russ Kincaid]

What I mean by "upside down" is: When the programmed output is high, the output actually goes low and when the programmed output is low, it actually goes high. I don't understand that.

Russ

[Pic_User]

Hi Russ,

What I mean by "upside down" is: When the programmed output is high, the output actually goes low and when the programmed output is low, it actually goes high.

We are not trying to give you a difficult time about this inverted waveform thing. It is just difficult to tell what you are seeing on a recurring waveform. Do you have another circuit synchronized with this output? Are you referencing the measurement to the PIC common?
The timing may be difficult to see with a rapidly cycling code. You could change the code to seconds, just to watch the sequence.

It looks like you WANT the output to be HIGH for three time increments and LOW for one. (See attachment.) http://www.picbasic.co.uk/forum/atta...1&d=1178466510
Is the waveform LOW for three time increments and HIGH for one?

-Adam-

[Russ Kincaid]

Hi Russ,



It looks like you WANT the output to be HIGH for three time increments and LOW for one. (See attachment.) http://www.picbasic.co.uk/forum/atta...1&d=1178466510
Is the waveform LOW for three time increments and HIGH for one?

-Adam-

Exactly right. Why does it do that?
BTW, GPIO.0 produces the positive half of an AC signal while GPIO.1 produces the negative half. The result is an AC that reads the same on a true RMS meter or one that reads 0.7 of the peak.