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DLPC900 firmware writing: Checksum byte in Download Data Command?

Matt Riggs
Prodigy 170 points
Other Parts Discussed in Thread: DLPC900

Hello! I have a question related to writing the DLPC900's firmware over USB:

In DLPU018B, section 2.2.7 "Download Data" describes the Download Data Command, and says that the maximum command length is 514, but table 2-27 shows a 515th byte labelled "checksum".

Is the true maximum command length 515? If the checksum byte is meant to be included, do I need to calculate a checksum on the data in the command? What checksum algorithm should I use to compute it?

Thanks for your help!

-Matt

  • 0
    TI__Mastermind 30875 points

    Hi Matt,

    There is mistake in the command definition. We will correct it soon.

    Please use the following guidelines -

    on the USB transaction you don't need to add BYTE0 and BYTE1 for the length; actually it will directly taken from USB message header (as described in Programmer's Guide Figure 1-4. USB HID Protocol).

    BYTE0-BYTE499 : Data Bytes

    Note:

    1. Checksum not used; you need not send

    2. Via USB,  as mentioned above you need not add payload size (covered in USB header); for I2C you need to add the number of bytes info in the payload

    Regards,

    Sanjeev