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PGA300: OWI communication failure rate

hui zhao
Prodigy 50 points
Part Number: PGA300
Other Parts Discussed in Thread: USB2ANY

I am working on the OWI communicate with my pressure sensor. my test software to drive OWI circuit to read the data from sensor.

there are two questions:

1. what is the OWI communication failure rate for 1200 bard rate? 

2. does it have time interval requirements between two commands for reading EEPROM data from PGA300?

  • 0
    TI__Mastermind 31655 points

    Hello Hui,

    There is no specification for the failure rate of the OWI communication. Are you experiencing dropped OWI packets, or incorrect data?

    No time specific time interval is required between two OWI commands. As long as OWI communication is not deactivated between commands, you can send another sync field to start a new command directly after the previous command is finished. There is an inter-field wait time between data fields of one bit-time, but this is not always necessary. If communication speed is critical, you can leave out the inter-field wait time, but if you experience incorrect communication, you can try adding it back in.

    Regards, 

  • 0 in reply to Scott Cummins
    Prodigy 50 points

    hello Scott,

    Thanks for your quick reply.

    for the communication failure rate, currently I did 3500 times read P_GAIN of PGA300 and got 2 times failure. I do not know if it is normal.

    so need your support for this.

    for the time interval of two command, I saw the description in SLDU022 (PGA300 EVM GUI) page 35 for the owi configuration. why the USB2ANY  need set a timeout to make sure it can receive correct value?

    currently I send the command to sensor read data using 200ms time interval. If I change this interval to 70ms, my test software can not read correct value.

  • 0 in reply to hui zhao
    TI__Mastermind 31655 points

    Hello Hui,

    If you are using the EVM, it has some rather tight limits for the OWI communication on the receiving end, as well as a rather narrow output range. To improve the OWI communication (especially at higher baud rates) you can use the modifications shown in the presentation below to improve its robustness.

    5670.OWIFix.pptx

    The time interval does not have anything to do with the OWI communication. It is purely related to the USB interface, and unfortunately it is best to use a larger time interval (generally 200ms or above) to maintain the best output.


    Regards,