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TMS570LS1224: GIOA2/EQEP2I pin muxing conflict

Poorva Bhargava
Prodigy 30 points
Part Number: TMS570LS1224
Other Parts Discussed in Thread: HALCOGEN

Hi,

I am using TMS570LS1224 Launch pad to interface a booster pack. The requirement is to use eQEP_2 module to interface with Quadrature Encoder.

GIOA_5, GIOA_2, GIOA_1 at  J4 on Launchpad are used to get Quadrature Encoder inputs (A,B and I) from Encoder at 5V to these GIO pins at 3.3V after a level shifter.

GIOA pins are configured as inputs and pull ups.

My issue is when I connect Encoder, through level shifter, I get correct Encoder Signals(A,B and I) on GIOA_5, GIO_2 and GIO_1 respectively. But at the same time I see Encoder (B pulse train ) on EQEP2I pin at J11(pin 12) without any connections.

I am unable to use eQEP module since I am not getting the encoder Index pulse on this pin, 

GIOA_2 and eQEP2I are pinmuxed.

Is this creating a problem? 

Regards,

Poorva

  • 0
    TI__Guru 59540 points

    Hello Poorva,

    I am a little confused by your question.

    Poorva Bhargava said:
    My issue is when I connect Encoder, through level shifter, I get correct Encoder Signals(A,B and I) on GIOA_5, GIO_2 and GIO_1 respectively.

    This means you are seeing the correct signals on the appropriate pins. Correct?

    Poorva Bhargava said:
    But at the same time I see Encoder (B pulse train ) on EQEP2I pin at J11(pin 12) without any connections.

    J11 pin 12 corresponds to the same MCU pin (pin 9) as GIOA_2 on J4. As you mention, the functions are muxed on this pin. You must select one or the other functionalities to use on this pin and cannot use GIOA_2 functionality and eQEP2I at the same time.But it is confusing because you are stating that you are getting correct signals at J4? The signals at J4 pin8 should be the same as J11 pin12.

    Poorva Bhargava said:

    I am unable to use eQEP module since I am not getting the encoder Index pulse on this pin, 

    GIOA_2 and eQEP2I are pinmuxed.

    Is this creating a problem? 

    You will need to select another pin for the B pulse train if you intend to use the eQEP2I pin for the index pulse. You will need to update the pin mux configuration in Halcogen to select the eQEP2I function on pin9.

    In case it would be helpful, the schematic for the Launchpad can be found at this link: processors.wiki.ti.com/.../LAUNCHXL2-TMS57012