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Switch RXD and TXD

GuyM
Intellectual 355 points
Other Parts Discussed in Thread: MSP430F5438A

Due to schematic error, I have a board which the RXD and TXD pins are switched.

Is there any creative way to change between their functionality internally in the MSP430? Or is it completely impossible due to hardware constrains?

Maybe using a software UART driver?

Thanks

  • 0
    TI__Expert 7535 points

    Hi GuyM,

    The answer to this question will depend on which MSP430 device you are using, and which peripheral on that device you were intending to use.  If you can provide this information I can help you select a good path.

    If you are using an MSP430F5/6xx device (5-Series or 6-Series) that has port mapping capability, and you are using pins on the port mappable port for the UART, then you can switch the RXD and TXD functions.  This is the best case scenario- chances are you don't have this option.

    If the above is not an option, there is not another way to switch the hardware pin functionality inside the device.  To your point, the you could implement a soft UART using a timer- however, you will be very limited in what data rates you can achieve.  If your design is low-volume, you may be best off cutting the traces and wiring them correctly- though a new PCB spin would be the best.

    Walter

  • 0 in reply to Walter Schnoor
    Intellectual 355 points

    Thank you Walter. I am using MSP430F5438A. I don't know if this one supports port mapping, but I'll check.

    Since I didn't think that software driver will be a good solution, I did exactly what you proposed - cutting the traces and wired the correct pins.

    It is an initial testing board, we'll fix it in the next round.

    Thanks a lot.

  • 0 in reply to GuyM
    TI__Expert 7535 points

    GuyM,

    Glad to hear that you were able to switch the traces.  The MSP430F5438A does not have a port mapping peripheral, so you would have needed to correct the traces physically anyways.

    In the future, if you would like to maintain some flexibility in port function after going to layout, the port mapping peripheral can be very helpful.  It is supported in the F51x, F52x, F53x, F55x, and F56x sub-families, and allows different peripheral functions to be connected to different pins, even at run time.

    Walter

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