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Using SCIA port on the DRV8301

GEOFF JACKSON
Expert 1535 points

Other Parts Discussed in Thread: MOTORWARE

I've been trying to use SCIA on the 69M-KIT board, connecting via J12 to GPIO28 and 29. I found that GPIO28 was pulled up to 3.3volts and any incoming signal from an RS232 chip was incapable of pulling the signal down.

Even when GPIO28 was configured as a general purpose input, pulling it down to ground was sinking 30mA, and I thought that this input must have been damaged.

It was when I looked at the schematics for the F28069M ISO control card that I realised that this GPIO pin is connected to the output of an ISO7220 signal isolator chip, and it was this that was pulling the pin high. As the isolator is connected to the 69M pin via SW3, I could disconnect the isolater, allowing GPIO28 and 29 to work as GPIO inputs.

Although the USB debug and programming interface seems to work fine with SW3 off, I'm not clear as to whether this signal is used at all by the motorware labs. The function of the switches on the ISO card don't seem to be documented anywhere that I can find, so can anyone clarify whether it's OK to disconnect the U21 isolator output to allow use of SCIA in my application ?

Geoff

  • 0
    TI__Guru** 114905 points

    Hi Geoff,

    I am moving your post to the C2000 microcontroller forum. They are more knowledge on the F28069.

  • 0
    Guru 13185 points

    Hello Geoff,

    As I know, it is fine to use GPIO28 and default motorware doesn't use it. I use GPIO28 for my SCI application with motorware however I don't use 69M ISO Control Card for this.

    So for more confirmed about the hardware part, let's wait the TI expert to answer.

    Best regards,

    Maria

  • 0 in reply to Maria Todorova
    Expert 1535 points

    Hello Maria,

    Thanks for your advice.

    I haven't had any reply on the forum from anyone at TI, so I just tried it and it seems to work fine, once the switch on the 69M ISO card was switched to off, disconnecting the isolator output from the GPIO pin. Obviously you wouldn't have this problem if you weren't using that control card.

    Anyway your experience and mine together seem to indicate that there's no conflict in using SCIA with motorware.

    Best Regards,

    Geoff

  • 0 in reply to GEOFF JACKSON
    Guru 13185 points

    Hello Geoff,

    Yes, it is no problem to use SCIA, also to use GPIO28/29. Just be careful and make sure the pins are isolated when connected related to high power part (because I think it became unisolated when SW3 is switched off).

    Best regards,

    Maria