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Is this an error in the 2802x documentation?

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Trying to figure out interrupts from GPIO pins. I think I found an error in one of the figs for the 2802x (tms320f28027.pdf Revised Jul 2012).


If I understand the function of XINT#CR and XINT#CTR where # is 1 to 3, the number should match to XINT#. In the figure, they do not.


Another question. Am I correct in understanding that only three GPIO pins at a time can cause interrupts? I want to attach 4 quadrature encoders as inputs. Will I have to poll these rather than use interrupts?


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Yes the diagram is incorrect. It should be XINT1CR/XINT1CTR...etc.


Yes, you are correct. Only 3 GPIOs at any given time can be used to create an interrupt, but you may select any 3 GPIOs. You may want to look at using the capture module. You could add a little external hardware to figure out the direction and then just use one of the quadrature signals piped into the capture to figure out rotations/velocity etc. There is only one channel though, so you'll probably need to use external interrupts and the capture.



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