Multiple Interrupts

Technical Programming
1

Hi, I was thinking of having and interrupt for the rising and falling edges from the geartooth sensors on each of two wheels as well as have a timer interrupt for each of three SONAR sensors. How do you program different interrupt handlers so that each one responds to a different interrupt from each device?

Thanks,
Windell
#2477

2

You only have one interrupt handler for your entire program. To handle multiple interrupts, you put a large amount of if-else statements in your interrupt handler to check for which particular interrupt you’re handling at the moment, then you do whatever you need to inside that particular if-else statement.

3

Ahh I see what you mean. Are there any examples that you can show me?

Thanks,
Windell

4

Kevin Watson’s encoder software is a good example of multiple interrupt sources being handled.

http://www.kevin.org/frc/frc_encoder.zip

Many of his other utilities, such as the adc and pwm replacements, are also useful examples.

5

I just had a bad idea. If you want interrupts on the rising AND falling edges…

void Int_1_ISR(void)
{
	INTCON2bits.INTEDG2 = !INTCON2bits.INTEDG2;
}

Mmm, does anyone smell the processor cooking?

6

Kevin would definitely be the one to ask, but i think that might work, if you also disabled the interrupt, then made the INTEDG2 change, and then reenabled it.

Alternatively, if you want rising and falling edges, just use the PORTB ones (Int3-6).

7

I did this for the 2004 IR beacon receiver and it works just fine (and no smoke or flames <grin>).

-Kevin

8

I have been trying to get Interrupts 2 and 3 working that would be on pins 1 and 2 of the Digital Inputs. I have the code and I seem to get in an infinite loop on the left gear tooth sensor. . . The interrupt keeps going and makes both the right and left gear boxes go full 254 forward.

Right GTS doesn’t work at all. (yes we have tested the GTS after we fixed the resistors problem and it works fine)

Can someone see where I messed up??? Copied the code from Kevin Watson’s Encoder Code.

team171a.txt (2.96 KB)
team171b.txt (1.12 KB)


team171a.txt (2.96 KB)
team171b.txt (1.12 KB)

9

I can’t really make out what’s going on, but I did see that you were calling printf() in your interrupt service routine, which can cause problems. A much better quick-and-dirty way to signal the outside world is to just send a single character using Write_Serial_Port_One(), which executes much faster. It’s as simple as this:

Write_Serial_Port_One(‘*’);

Fix this one problem and let us know if it works.

-Kevin

10

I originally had no printf’s and was having the problem. Then added them in to see additionally what could have been causing problems.

11

I was unaware of a resistor problem. What is the problem that you speak of?

12

Team Update #6 explains it. There are a bunch of discussion here on ChiefDelphi about it also. . . Pretty much they switched R3 and R4 on one of the Gear Tooth Sensors

13

I changed all the Longs to Ints
Took out the printf in the interrupt function.

And everything started to work!!!. . . With making those few changes the above code works for Digital Input 1 and Digital Input 2 Gear Tooth Sensors.

It really made me excited today when programming the robot to go *** (A calculated value) gear teeth (8 ft) forward it actually did.

14

whoa! Congrats! I’ll be sure to remember that when I get around to the closed loop feedback.