Multi-Threading

[Ted's]

skimask, I recommend to you to read the other posts and my replies.

To me an interrupt means:

-Stop the current main program.
-Execute the interrupt routine
-Go back to where you came from in the main routine.

Basically interrupts should show a possible way to create the impression of multithreading. But.

But imagine there is a servo motor. The motor needs a signal every 20ms to keep it's torque. So the interrupt starts the interrupt routine. The interrupt routine should take say 2 seconds. And within these two seconds there is the action of force onto the motor.

This is what I was alluding to when writing about the pauseus issue. This stands for reserving time within the interrupt routine.

Or do DT's includes make the pic execute the code (even the main code) by cycling through each interrupt each cycle of code execution? So using a 20Mhz quarz leads to processing a portion of each code every 0.2 us?

I appreciate that you want to answer my questions to my satisfaction. Then give me a code example showing how to do that with DT's includes.

[skimask]

skimask, I recommend to you to read the other posts and my replies.

Hey, Good Idea! Why didn't I think of that....

To me an interrupt means:

-Stop the current main program.
-Execute the interrupt routine
-Go back to where you came from in the main routine.

Basically interrupts should show a possible way to create the impression of multithreading. But.

So far, so good...

But imagine there is a servo motor. The motor needs a signal every 20ms to keep it's torque. So the interrupt starts the interrupt routine. The interrupt routine should take say 2 seconds. And within these two seconds there is the action of force onto the motor.

This is what I was alluding to when writing about the pauseus issue. This stands for reserving time within the interrupt routine.

Or do DT's includes make the pic execute the code (even the main code) by cycling through each interrupt each cycle of code execution? So using a 20Mhz quarz leads to processing a portion of each code every 0.2 us?

You're thinking too linearly...stuck inside a box.
Keep track of a timer/counter that gets tipped much faster than every 20ms. Hit the servo, wait 20ms later (and servo's don't NEED exactly 20ms), hit the servo again.
If those LEDs I eluded to earlier miss a pulse completely, I'll see flickering. If one of those pulses is just a bit off, I most likely won't see anything...but quite frankly, they're solid, nice and smooth. So, from THAT programming standpoint, there isn't much of a difference between LEDs and Servos. Interrupts work great for me and a load of other people. You aren't any different.

I appreciate that you want to answer my questions to my satisfaction. Then give me a code example showing how to do that with DT's includes.

I don't want to. Just making a point based on your last 'thread' (if we can call it that)....
And it's YOUR job to give US a code example of how to do anything with DT's Instant Interrupts...and WE will HELP YOU figure out why it doesn't work the way YOU want it to work.
And what's wrong with the examples in the instant interrupt threads?

[Darrel Taylor]

And what's wrong with the examples in the instant interrupt threads?

I'd like to know that too.
<br>

[Jumper]

So we have one led you want to flash in a fading way.

How frequently do you want to flash it?

Do you want to do other stuff while flashing the LED? In that case what will the PIC do?

Can you put the LED on PORTB.3?

How fast do you want to fade it up and down?

How smooth do you need it, how many steps would you like the led to have on the way up and down?


Before we even try to untangle the code for this it would be nice to know that you can use this pin and get the other information as well.

/me

[skimask]

Can you put the LED on PORTB.3?

I'd doubt it...
http://www.picbasic.co.uk/forum/showthread.php?t=9275
Check post #32 and #33!

[Ted's]

Jumper if you want to design a code example do not stick to values, stick to variables instead. Frequency should be f. Other concurrent thread(s) exist while fading in/out. There is no data available about them yet. Just use "LED", I'll use a pointer to the right port like LED VAR PORTX.Y. Speed of fading should be a function of frequency. Freqency means: every 1/f seconds there is a change. If LED is off, Led_fade_routine starts and vv. Led_fade_routine consists of fade_in_time = 2/f and fade_out_time = 2/f. Smoothness depends on OSC. Should be as smooth as possible, ie chunks_duration should be at a minimum.

Thanks for your initiative. I appreciate that.

[Jumper]

Did I miss something? In my code example I have LED as an alias for a port and I can't see I use any other values than T1CON (which is a register).

If you are referring to my question about moving the LED to PORTB.3 it is only because I wanted to know if it was possible, and in that case we could use the HPWM for the fading. Doing that way would take very little instruction time and still give a nice fading effect since we only need to change the dutycycle once in a while to get a very smooth fading effect.

I am deeply sorry that my poorly written code example upset you.

over and out

/me

[Melanie]

Ted stop winding people up that are trying to help you. Folks give up their time for free around here. If you don't like an answer then be polite, say "Thank You" to acknowledge the time they may have devoted to potentially a lost cause, and move on.

In case you're not aware... the short answer to your question at Post #1 is Yes.

If yor PIC has ADC, Comparators, CCPM, USART etc the you can SIMULTANEOUSLY perform any or all of those functions whilst doing something else altogether AT THE SAME INSTANT IN TIME. Go do a forum SEARCH, this has been discussed before.

Alternatively you can TIME-SLICE your code... in the simplest form, using your flashing LED for example, say the LED is flashing at a 2Hz rate, you can switch ON your LED, then go do something else for 250mS before you need to devote an instruction to switching it OFF Gee... at 4MHz, that's a shed load of instructions you can carry out whilst that LED is ON, and again when it's OFF. To the casual observer, it will appear as if the PIC is doing multiple tasks.