• Resolved

CCS/TMS320F28377D: SCI communication issue - Unrecognized characters on the hyperterminal

Prodigy 60 points

Replies: 5

Views: 123

Part Number: TMS320F28377D

Tool/software: Code Composer Studio

I am using Delfino F2837x Control Card R1.1 and Docking Station R4.1. I have installed CCS8.3.

I have a trouble in setting up the SCI communication. I could see unrecognized characters on the serial port when i transmit the data in the SCI line. I have tried with SCI A and SCI B.

I see the same issue has been discussed, but no solution has been suggested. Refer the thread below.

https://e2e.ti.com/support/microcontrollers/c2000/f/171/t/383495 

  • Check your baud rate. 

    1. Put a scope probe on the transmit line.

    2. Find the smallest pulse.

    3. Measure the width of the smallest pulse.

    4. The inverse of the width is your baud rate.  For example, if your smallest pulse is 10.4uS, then you have 9600 baud. ( 1 / 10.4uS = 96154)

    Remember that your actual baud rate must be within 3% of the ideal baud rate.  So if the transmitted signal's measured baud was actually 9900 baud, it will not work with a 9600 baud receiver.

  • In reply to quark:

    Hi Munaf,

    There is actually a resolution on the second page of the thread you linked:

    Are you trying to communicate via the virtual COM port of the FTDI chip, or directly to the serial port of a PC?  If not through the FTDI you will need an RS-232 transceiver since RS-232 doesn't use CMOS logic levels.  

    Did a reply answer your question? If yes, please click the "Resolved" button located at the bottom of that post.
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  • In reply to Devin Cottier:

    Hi Devin,

    Thank you for the reply.

     

    Below set of activities i could confirm,

    1. Measured baud rate on the scope and it matches with my SCI configuration.

    2. Bit pattern on the scope is matching with the data that has been transmitted. 

    3. FTDI virtual com port does read the data that i have transmitted.

    I am trying to read through the com port of my PC. I am using the RS232 serial transceiver (see link below)

    https://www.insight.com/en_US/buy/product/ICUSB2321X/STARTECH.COM/ICUSB2321X/StarTechcom-1-Port-Professional-USB-to-Serial-Adapter-Cable-with-COM-Retention--serial-adapter/

    On the docking station [R4.1] , i have connected pin 78(GPIO29, SCITXA) to the RS232 receiver pin.  Connected the ground pin of docking station and RS232 transceiver to make sure the common ground

    I could see random characters received on my PC com port. 

    I have experimented this with TTL to USB converter and still see random characters on the PC com port.

    Did i miss any setting on the controller card to rout the SCI signal to the docking station pin (76 and 78).

    Please help to resolve this issue.

    Thanks & Regards,

    Munaf

  • In reply to Munaf Shaik:

    Hi Munaf,

    The link you provided is for a RS-232 to USB adapter, but I think you will also need a RS-232 transceiver.  RS-232 levels are about +/-13V, so the 0 to 3.3V coming from the MCU will not be sufficient.  e.g. http://www.ti.com/product/TRS3253E

    Did a reply answer your question? If yes, please click the "Resolved" button located at the bottom of that post.
    Visit these helpful C2000 Links!

    C2000 TI Wiki Pages
    TI Forum Sitemap

    ControlSUITE
    C2000 Getting Started

    CLA FAQs
    Workshop Material!

  • In reply to Devin Cottier:

    Hi Devin,

    Thank you for the reply.

    I have used TTL UART module (see link below) for SCI communication and its working. I am able to see the characters i sent on the communication port.

    https://www.indiamart.com/proddetail/cp2102-usb-2-0-to-ttl-uart-module-6pin-black-16435883791.html 

    Thank you for all the support.

    Munaf