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F28335 Experimenter Kit SCI-A (USB-VCP) Rx Problem

Paul Raine
Intellectual 580 points
Other Parts Discussed in Thread: CONTROLSUITE, MAX232

Hi,

 

We recently purchased a F28335 PGF controlCard Release 1.0 (TMDSCNCD28335PGF  R1.0) and docking station/breakout board (USB-EMU)....

I'm hoping to establish a bi-directional UART connection between my F28335 Experimenter Kit and the PC.

I imported the Example_2833xSci_Echoback project, compiled and started it. I have connected the USB-VCP to a terminal application on my PC.

When I run the example code, the transmit is working (I see messages on the PC Terminal), however the F2833 doesn't receive any character I send from the PC Terminal.

 

It never reaches the line after the following code line:

 

// Wait for inc character
while(SciaRegs.SCIFFRX.bit.RXFFST !=1) { } // wait for XRDY =1 for empty state

 

I verified the communication with a port monitor application and it showed that those characters were really sent from the PC.

I also monitored Pin GPIO28 and GPIO29 using a scope on the breakout board. I see Tx data on pin GPIO29, but no Rx data on GPIO28.

Do I need any jumper or switch changes on the board? I don't see anything in the documentation that describes how the data gets from the USB to to the SCI-A Port.

 

Any information you can provide would be greatly appreciated.

Thank you.

  • 0
    Mastermind 7585 points

    There is a non-populated jumper (J9) at the USB-Emu Docking station. Just close J9 and the SCI (FTDI) is working bidirectional (see schematics file in ControlSuite).

     

     

  • 0 in reply to Frank Bormann
    Intellectual 580 points

    Thank you Frank,

    We got the example code working for bi-directional communications. It was unpopulated the Jumper (J9) we needed to connect... and switch SW1 needed to be in the OFF position. We also found the schematics files in the ControlSUITE, as you suggested. (We had wrongly presumed there was just software info in there!)

    Thank you for the quick and helpful response. Without doubt, you saved us a large amount of time!

     

  • 0 in reply to Paul Raine
    Intellectual 620 points

    Hello,

    I have the similar problem. However, when I close J9, I still can not send data from PC to F28335. Someone says I need to remove R24 on control card. Is that true?

    Thanks.

  • 0 in reply to Fei Pan
    Mastermind 7585 points

    Just follow the recommendations from above: (a) switch SW1 in OFF, (b) populate jumper J9 and you can receive SCI data from the FTDI - channel.  Resisitor R24 (and R13) are not related to this.  As shown in the schematics, they will connect the ground and 3.3V from the DSP-side to the isolated MAX232 side of the non - FTDI - UART.

     

     

  • 0 in reply to Frank Bormann
    Intellectual 620 points

    Hello Frank,

    Thanks. I solve this problem now. I find the reason is that I am using an old version of control card R1.2. I have to remove R24 and populate J9 and J8. And this bi-directional communication is working now.

    Fei