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McBSP enable XFRLEN1

Grzegorz Brzuchalski
Prodigy 70 points

Hi,

I am using c6474. I try to communicate by McBSP1 and I have troubles with its configuration.

I do something like that:

1. I set XRST, RRST, GRST, FRST to 0.

2. I set value XFRLEN1 to e.g.3

3. I set value XWDLEN1 to 32 bits

5.FREE=1, SOFT=0, FSXM=1, CLKXM=1, CLKSTP = '11', CLKSM=1, FSGM=1

4. I set XRST, RRST, GRST, FRST to 1.

When I start sending packets from DSP I see with oscilloscope that:

words has 32 bits

FSX come after each 32 word.

When I change XWDLEN1 to other values it works.

Why  XFRLEN1 does not work? How to enable it?

Similar problem I have with FWID (always it has 1 bit), XPHASE (always one phase).

I have checked registers values in memory browser and their are correct.

Regards,

Gregory

  • 0
    TI__Mastermind 35645 points

    Hi Gregory,

    Thanks for your post.

    Usually, frame length specifies the maximum number of serial elements or logical time slots or channels that are available for transfer per frame and you can program the the frame length fields with (w minus 1), where w represents the number of elements per frame. You can refer Table 8 in Section 4.5.2 for receive/transmit frame length configuration from c6474 mcbsp userguide as below:

    http://www.ti.com/lit/ug/sprug17a/sprug17a.pdf

    XFRLEN1 can be configured through transmit control register (XCR) which refers the transmit frame length as number of words in phase 1. Please refer section 11.5, Table 21 for XCR field descriptions from the above mcbsp user guide.

    Kindly ensure your XFRLEN1 configuration and enable accordingly.

    Thanks & regards,

    Sivaraj K

    ----------------------------------------------------------------------------------------------------------------

    Please click the "Verify Answer" button on this post if it answers your question.

    ----------------------------------------------------------------------------------------------------------------

  • 0 in reply to Sivaraj Kuppuraj
    Prodigy 70 points

    Thank you for your reply.

    I have read this userguide and I think I have done everything correctly. (Value in XFRLEN1==2, FPER==31) and FSX come with every 32 bit but CLK is only for 8 bits, so I suppose I am sending only one byte in frame instead 3 bytes. Maybe sending procedure is incorrect? I have tried two solutions:

    MCBSP1->DXR = 0xFFFFFF;

    or

    MCBSP1->DXR = 0xFF;
MCBSP1->DXR = 0xFF;
MCBSP1->DXR = 0xFF;

  • 0 in reply to Grzegorz Brzuchalski
    Prodigy 70 points

    I have solved my problem. CLKSTP should be set to '00'.

    Thank you.

  • 0 in reply to Grzegorz Brzuchalski
    TI__Guru* 81335 points
    Hi Grzegorz Brzuchalski,
    Thank you for the update.