Disable the RTC?

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Hello All,

There is a board with BlackFin BF-537 DSP. We are not using the RTC which is
built in BlackFin. I want to disable the RTC to avoid any unwanted activity.
There is no way to disable the RTC by software. The RTC has the separate
power supply input (VDDRTC), and the pins for connecting a 32k XTAL (RTXI
and RTXO respectively).
The datasheet says nothing on this matter. The customer support has no clue
as usual.
It seems logical to me that the VDDRTC should stay connected, and the RTXI
should be pulled to the ground.
What would be your opinion about that?

Vladimir Vassilevsky
DSP and Mixed Signal Consultant

Re: Disable the RTC?

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TI tech support (at least 5 years ago) was way better than that.  You
could tell that all the hard questions went to Hyderabad where they would
be researched at $10/hour, but one generally got answers -- even to
obscure questions -- in the following morning's email.

At a guess, I would say you're doing the right thing, although if the RTC
can be separately powered _up_ it may well be able to separately power it

Tim Wescott
Control systems and communications consulting
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Re: Disable the RTC?

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When I asked TI about the internal structure of the TAS3004 filters,
they send me to the 7th level of support (whatever it means), and then
refused to disclose any details.

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OK, I found the recomendation in the hw. manual which states exactly the
same thing: pull RTXI to the GND and leave the VDDRTC connected to VDD.

As for the customer support, they are not supposed to know and to
provide any information beyond what was already published in the manuals
and appnotes. Sometimes you can get an additional information on the
NDA, but only sometimes.

Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant

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