BF522 ppi clock issue

Hi ADI's

One of my customers is trying to build a system like this:

The behavior of the ppi timer is strange.

ppi timer circuit
 
Clkbuf out-> ppi clock in (blue connection)
 
2. External CLOCK-> ppi clock in (when connected red)
  DAC output error

It seems to be caused by a mismatch between the system clock and fs.
Is there a way to change the internal ppi clock of the BF522?

Thank you



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[edited by: Andrew.Choi at 8:42 AM (GMT 0) on 24 Oct 2019]
  • 0
    •  Analog Employees 
    on Oct 25, 2019 2:40 PM

    Hi Andrew,

    1) Regarding, " Clkbuf out-> ppi clock in (blue connection) and External CLOCK-> ppi clock in (when connected red). It seems to be caused by a mismatch between the system clock and fs."

    >> Please refer BF52x HRM Page no: 611," Frame Synchronization in GP Modes". Please refer the attached code.
    www.analog.com/.../ADSP-BF52x_hwr_rev1.2.pdf

    2) Program the "PPI_DELAY" register with some values. In TX modes using at least one frame sync, there is a one-cycle delay beyond what is specified in the PPI_DELAY register. If the delay register value for Tx is 1.
    Then use Rx delay register value as 2 or 4.

    3) The PPI_CLK pin accepts an external clock input. It cannot source a clock internally. When the PPI_CLK is not free-running, there may be additional latency cycles before data gets received or transmitted. In RX and
    TX modes, there may be at least 2 cycles latency before valid data is received or transmitted.

    Please find the attached code for your reference.

    Regards,
    Anand Selvaraj.PPI_BF527.zip