QEI: Software disabling of IDX

david genge

Other Parts Discussed in Thread: TM4C123GH6PM

Hi Sue,

I am using both QEIs on the tm4c123gh6pm launchpad board.

Neither of the encoders on the motors outputs an index signal.

I thought great! that will give me two pins I can use as outputs to control the 'direction' on the h-bridges driving the motors.

It appears, though, that the index pins cannot be re-purposed after the QEI modules are enabled.

Please tell me I'm wrong and how to use the index pins as outputs!

Cheers,

Dave

over 11 years ago

0 Bobby Bradford over 11 years ago

TI__Genius 10040 points

Dave,

If you do not specifically configure the pins to be used as QEI index pins, they should remain configured as GPIO signals by default. You should be able to access those signals using the GPIO APIs.

If your application is configuration all QEI signals to be controlled by the QEI module, you may simply need to remove the configuration of the index signals, and reconfigure them as GPIO outputs.

--Bobby

0 david genge over 10 years ago in reply to Bobby Bradford

Intellectual 600 points

Hello Bobby,

It's been a while but I am happy to report that you are quite correct.

I've been able to use one of the index pins for pwm output. Wahoo!.

Thanks.

Dave

0 Amit Ashara over 10 years ago in reply to david genge

TI__Guru**** 244400 points

Hello Dave,

As per the QEI spec there are two modes: One which uses the Index Pulse and one that does not. Glad that you have the second option working.

Regards
Amit

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QEI: Software disabling of IDX