Encoders not changing...

[paulcd2000]

i implemented the encoder file from Kevin's site... but it doesn't work. I plugged it in to what it said, and i update it with:

        LeftWheelCount = Get_Encoder_1_Count();
        RightWheelCount = Get_Encoder_2_Count();

what could my problem be?

[Joohoo]

what other code is being implemented are you using the camera?...GTS?...timers?...other sensors?

make sure the encoder outputs are plugged into the correct inputs.

make sure you are using the right type of encoder, I believe that kevin watson has his code set up for a quadrature encoder.

also make sure that you call all the right functions in the right places ie. encoder_counter() in Interrupt_Vector_low(), encoder1_init() in user_init().

another problem that happened to me was overlapping interrupts. If you do a "find in project" for a bit in the register to see if they are used anywhere else, you may eliminate this problem.

[bear24rw]

Did you follow the steps in the readme that came with the encode code.. such as adding the initialization call?

[paulcd2000]

i did follow the steps in the initialization. i am also using the camera. I'll check the encoder type. Where do i find what kind they are exactly? I do call Initialize_encoders() in initialization, and i call interupt handler low from Default routine.

[Alan Anderson]

Originally Posted by paulcd2000

...i call interupt handler low from Default routine.

Don't do that.

The interrupt handler is "called" by a hardware feature of the processor. You don't have to do anything more than define it as the interrupt handler.

[paulcd2000]

k thanks... still haven't gotten a chance to test again

EDIT: nope, still doesn't work...

[Manoel]

How do you know the encoders are not changing? Are you simply trying to print your xxxxWheelCount variables to a terminal and noticed they don't change?
If so, then that's likely the only problem and your encoders are just fine. Your variables are probably declared long int and, as such, you need to typecast them before printing. Try the following:

printf("Left encoder = %d", (int)LeftWheelCount\r\n);

and see if it works. Sometimes the simple things really get on your way!

[paulcd2000]

actually, they're not longs. they're ints. a long can hold up to 2147483648, which is about a mile. i just used ints. they're printed using

printf("Left Encoder: %d\t Right Encoder: %d\r", LeftWheelCnt, RightWheelCnt);

But it's a good point. i'll try printing the values directly from the method...

[paulcd2000]

did anyone have to change their encoder code to get it working? what did you do? cuz ours still isn't working

[Alan Anderson]

Originally Posted by paulcd2000

did anyone have to change their encoder code to get it working? what did you do?

I tossed a USB flash drive containing Kevin Watson's frc_encoder.zip file to the lead student programmer and told him to follow the directions in encoder_readme.txt. He did the nine required steps and compiled it. I added a tiny bit of code in Process_Data_From_Local_IO() to turn the raw encoder counts into odometer and heading information, and put a printf statement in Process_Data_From_Master_uP() to verify the proper operation of the encoders.

That's it. It was painless.

[paulcd2000]

does the type of encoder affect the code? where did you guys get your encoders?

[Astronouth7303]

Are you sure the RC is reading the sensors correctly?

What I did to test our GTS's last year was put the last 4 PWMs in User_CCP mode (digital outputs should work equally well) and have the interrupt handler toggle that. I then hooked an oscilloscope to both the GTS and the CCP pin. The wave forms matched nearly perfectly.

In terms of software, the GTS and encoders should be very similar, ignoring direction. Even just putting an LED on the output pin and watching its apparent brightness should be helpful. (You probably won't see flickering, as it goes too fast.)

If that works, you may need to post your code so that we can look at it.

[paulcd2000]

i've got one last test to determine if the problem is programming or electrical/mechanical at the root. In interrupt handler low:

	else if (INTCON3bits.INT2IF && INTCON3bits.INT2IE) // encoder 1 interrupt?
	{ 
		INTCON3bits.INT2IF = 0; // clear the interrupt flag
		#ifdef ENABLE_ENCODER_1
	-->    puts("1");
		Encoder_1_Int_Handler(); // call the left encoder interrupt handler (in encoder.c)
		#endif
	}
	else if (INTCON3bits.INT3IF && INTCON3bits.INT3IE) // encoder 2 interrupt?
	{
		INTCON3bits.INT3IF = 0; // clear the interrupt flag
		#ifdef ENABLE_ENCODER_2
	-->    puts("2");
		Encoder_2_Int_Handler(); // call right encoder interrupt handler (in encoder.c)
		#endif
	}

The "puts" will output to my screen every time the interupt is called. if it never gets called, then the problem in electrical/mechanical in origin. Does anyone see a problem with my logic? (I'll test it friday at 3:00)

[paulcd2000]

I finally fixed it!!!! yES!! But i have no idea why it didn't work. Oh well... Thank you, everyone, for your help!

[JHale]

Originally Posted by paulcd2000

I finally fixed it!!!! yES!! But i have no idea why it didn't work. Oh well... Thank you, everyone, for your help!

Any chance in sharing what you did (I know the post is late). We are having problems with the code as well, and have ruled out the possibility of a problem with the encoders with an oscilloscope.