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F28335 Experimenter Kit UART

Christoph Kammer
Prodigy 50 points

Hi everyone,

I have an F28335 Experimenter Kit with a Rel-1.2 ControlCard. I would like to send and receive data to and from another Atmega Microcontroller via the TX/RX pins at J3.

I tried to modify the Sci_Echoback example, but I cant get it to work properly. I receive wrong data and after 2-3 transmissions it breaks (gets stuck at while(SciaRegs.SCIFFRX.bit.RXFFST !=1) { }). 

Mainly, I would like to ask if the USB-connection is somehow interfering and how to exactly initialize everything to send/receive data via J3.

Thanks in advance!

Regards, Christoph

  • 0
    Prodigy 50 points

    Update: I monitored the voltage on an Osci and when I sent data to my PC (working fine), I found the following:

    The voltage on the TX pin of my Atmega is at 3.3V, periodically dropping to 0V if something is transmitted.

    The voltage on the J3-TX pin of my ExperimenterKit is a 0V and peaking to 5V if something is transmitted to my PC via USB (which if I understood this correctly is totally wrong).

     

    Any help please? :(

  • 0 in reply to Christoph Kammer
    TI__Guru 57255 points

    Christoph,

    By default, the R1.2 F28335 controlCARD should only interact with J3 of the Experimenter's Kit.  It should work as long as you have not placed a jumper on the Experimenter's Kit J9, have not removed R24 on the controlCARD, and are not using GPIO28 or GPIO29 for something else in your system.


    [CK]The voltage on the J3-TX pin of my ExperimenterKit is a 0V and peaking to 5V if something is transmitted to my PC via USB (which if I understood this correctly is totally wrong).
    [BL] What do you mean by this statement?  How are you communicating from the PC to  the F28335?  Via a USB-to-Serial adapter bridge connected to J3?



    Thank you,
    Brett