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uPP start signal timing and enable

UNA
Mastermind 7980 points

Hi,

 

I have a same ploblem.

I'm also using uPP(C6655) to receive data from FPGA with start signal. but, I can not receive the data correctly.

After the enable signal is inactive, uPP does not receive the data when enable signal become active again.

In order to receive the data successfully, It seems that it is necessary to reactivate start signal and enable signal.

So please tell me the role of start signal and correct timing graph.

 

Best regards,

Chi

  • 0
    TI__Mastermind 30825 points

    From Table 2-2 Of the uPP UG

    CHA_START        A                Output Input Indicates first data word per line of data
    CHA_ENABLE     A                Output Input Indicates data transmission active

    Descrpition of START signal

    The uPP transmitter asserts the START signal when it transfers the first word of a data
    line. A line is defined in terms of the channel’s associated DMA channel; for more on
    DMA programming concepts, see Section 2.4. The START signal is active-high by
    default, but its polarity is controlled by the STARTPOLx bit in UPICR.


    In transmit mode, START is an output signal and is always driven; in receive mode,
    START is an input signal and may be disabled using the STARTx bit in UPICR.
    When the channel is configured in transmit mode with data interleave enabled
    (SDRTXIL = 1 in UPCTL), the START signal function changes completely. The


    START signal now asserts on every data word that is provided by DMA Channel I. See
    Section 2.5.7 for this alternative behavior.

    I hope this helps to provide better understanding of the use of the START signal.

    Best Regards,

    Chad

  • 0 in reply to Chad Courtney
    Mastermind 7980 points

    Hi Chad

    Thank you for your reply.

     

    Is Timing chart of uPP UG  shown below  a graph  when the Start signal is Enabled(UPICR.START=1)?

    "Figure 2-4 Signal Timing for uPP Channel in Receive Mode with Single Data Rate"

     

    When Start signal is Disabled(UPICR.START=0),I can also receive data of D4 and later(D5,D6 ...).

    So, I think that it is need reactivate start signal and enable signal to receive the data of D4 and later, when Start signal is Enabled(UPICR.START=1).

    Is my thinking correct?

     

    Best regards,

    Chi