Part Number:TMS320C5517
Hi,
My customer have a question about C5517 RTC.
In their system, RTC of C5517 are not used and don't need it.
So, they are planning to connect DVDDRTC to ground(VSS).
As mentioned in datasheet page.48 as follow,
they will going to configure WAKEUP pin as output by RTCPMGT register setting.
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DVDDRTC can be tied to ground (VSS) when RTC_CLKOUT and WAKEUP pins are
not used permanently. In this case, the WAKEUP pin must be configured as output
by software. (See Table 5-1, RTCPMGT Register Bit Descriptions.)
*************************************************************
But in datasheet page.64 "Table 5-1 RTCPMGT Register", it said as follow:
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When the WAKEUP pin is configured as an output, is an open-drain that is
active low and should be externally pulled-up via a 10-kΩ resistor to DVDDRTC.
******************************************************************************
It said, WAKEUP pin should be externally pulled-up to DVDDRTC.
But as above description of datasheet page.48, DVDDRTC will be tied to ground.
And additionally, they don't need RTC peripheral, so they might disable the RTC oscillator
by connecting the RTC_XI pin to CVDDRTC and the RTC_XO pin to ground.
In this case, RTC register(include RTCPMGT register) will not be accessible as mentioning
in datasheet page.82 "5.7.4.2 Clock Considerations" as follow:
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The 32.768-kHz crystal can be disabled if the RTC peripheral is not being used. However, when the RTC
oscillator is disabled, the RTC peripheral will not operate and the RTC registers (I/O address range
1900h – 197Fh) will not be accessible. This includes the RTC power management register (RTCPMGT)
which controls the RTCLKOUT and WAKEUP pins. To disable the RTC oscillator, connect the RTC_XI pin
to CVDDRTC and the RTC_XO pin to ground.
**************************************************************************
It seem that information in the datasheet are inconsistent, so that we are confused.
When RTC peripheral is not used, how should we process the pins of RTC
and what kind of register setting are needed?
best regards,
g.f.