Use MISCA[4-5] to invert a DAI signal

Hello,

I have a similar question as Use SRU to invert SPI DS? . My project is based on ADSP-21488. I have a signal on DAI_PB10 and at some point I would like an inverted variant to be routed, for example to DAI_PB03_I. I was under the impression that this is feasible with MISCA4 or MISCA5, using the INV_MISCA[4-5]_I. My initial routing contains this:

SRU(LOW,DAI_PBEN10_I); // Pin Buffer 10 as input (OSC)
SRU(HIGH,DAI_PBEN03_I); // Pin Buffer  3 as output (OSC#)
SRU(DAI_PB10_O,MISCA5_I); // Route DA10 to miscellaneous buffer A5 (OSC -> MISCA5)
SRU(MISCA5_O,DAI_PB03_I); // Route MISCA5 to DA03 (OSC# -> DA03)
SRU(HIGH,INV_MISCA5_I); // invert miscellaneous buffer A5 output (MISCA5 -> OSC#)

But unfortunately DAI_PB03 output stands completely still.

Shouldn't this do the job?

I tried something similar with the polarity inversion on DAI_PB20 (using INV_DAI_PB20_I), which works fine, but I'd rather not waste that DAI pin if it can be done with MISCA[4-5].

Best regards,

Rolf

  • 0
    •  Analog Employees 
    on Jan 19, 2018 10:42 AM

    Not sure if its still open, apologies in case you could not resolve this in quickly.

  • Hi Jithul

    actually yes, this is still open. Aside from this workaround:

    I tried something similar with the polarity inversion on DAI_PB20 (using INV_DAI_PB20_I), which works fine [...]

    I'd still like to know whether polarity inversion of my signal is at all possible with MISCA[4-5]?

    Any help is appreciated.

  • 0
    •  Analog Employees 
    on Feb 2, 2018 7:14 AM

    Hi Rolf,

    Please note that MISCAx_O signals are listed under Group F Sources, and the destination signal control register for Group F sources are the pin buffer enable registers (SRU_PBENx), so it cannot be connected to any DAI_PB0x_I register as you are trying to do.

    For better insight see the Table A-81. Group F Sources – Pin Output Enable  and Destination Signal Control Registers (SRU_PBENx) shown in Figure A-86 through Figure A-89 in the HRM

    Routing can be something like, SRU(MISCA4_O, PBEN14_I); // connect MISCA to PBEN14

    But cannot be like, SRU(MISCA5_O,DAI_PB03_I); // Route MISCA5 to DA03 


    An example for this is given in the Figure 10-20. SRU Connection SPORT/PCG to MISC/DAI Pin Buffers
     (page# 544) in the HRM.

    Best Regards,

    Jithul