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TM4C123GH6PM: Quick Quadrature Encoder Question: What does the index pin do?

Matthew Hardenburgh
Prodigy 20 points
Part Number: TM4C123GH6PM

Sorry if this sounds like a dumb question, but I couldn't find a source that explains what this pin does or what to do with it (Yes, I have read the datasheet and the design guide). My motors have a Phase A and Phase B output pins, but no index output pins. Should I just leave it NC or connect it to ground? Thanks!

  • 0
    TI__Guru*** 135355 points
    Hello Matthew,

    The index signal can be used to reset the position counter. The position counter is reset when either an index pulse is received, or the max potential value is hit. If there is no index pin, then be sure to set the RESMODE bit of the QEICTL register to be zero. Section 21.3 has further details about how the settings work. I see no reason you have to make a connection to it, so you should be okay leaving it as an NC.
  • 0
    Prodigy 20 points

    Awesome! This helped a lot! Thank you guys for your responses!

  • 0 in reply to Ralph Jacobi
    TI__Guru 72500 points
    Some additional discussion on "what to do with unused pins" was split and moved to:
    e2e.ti.com/.../614779
  • 0 in reply to Bob Crosby
    Guru 117855 points

    Bob Crosby said:
    Some additional discussion on "what to do with unused pins" was split and moved to:

    That's of great value to many here (especially the o.p.) thank you.

    That said - is there not an (unwanted) "degree of difficulty" in (both) noting - and then searching/finding (maybe) - such "key, MCU related, Tech Data?"

    You are clearly, "Not the cause" - yet the, "Absence of well noted - and eased access" - to such "helpful MCU Data" - reduces client efficiency & remains curious...   (and unhelpful)