dm365 rtc

Please see section 1.4.1.1 on initialization procedures.  One important detail to be aware of is that the PRTCSS WDT must be cleared or else the RTC will power down.

Hi Marcus,

Thanks for your prompt reply.

>Please see section 1.4.1.1 on initialization procedures

In what document exactly?

Regards,

Shlomo

We are currently running the rtc in external mode.

Should we modifiy our hardware to work in NORMAL mode?

We are using the latest version of the Linux drivers

Shlomo

The document I was referring to was the TMS320DM36x DMSoC Power Management and Real-Time Clock Subsystem User's Guide (Rev. A) 

http://focus.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=sprufj0a&fileType=pdf

 I thought you were configure to normal mode.  Since you're in external mode then you'll need to be sure that the RESETz pin is held high during reset

1.4.2 External Reset Mode

Marcus,

I want to make sure I understand this, so I have to go slow.  In order to put the PRTCSS module into external mode, it's required to pull PWRST low.  If I want to use it in external mode then I have to handle the on/off, low power interrupt, and reset for the ARM - right?

BUt now, according to that statement in section 1.4.2, if I send a reset signal to the ARM I also need to pull the PWRST pin high, right?  (DOes 'device' in that section mean the DM365?)

If that is the case, can I use the reset signal itself to control the inverting of PWRST, or will the timing be too difficult?  I guess the question is at what point does the ARM actually reset and can I get PWRST high before that point to prevent losing the rtc data.

Am I understanding this correctly?

Thanks,

-David

The scenario I believe you're attempting to cover is PTRCSS remains on (no loss of data) while the other DM365 is in low power mode or to reset the ARM.  Is this the correct understanding?

To put the PRTCSS into external mode you'll need to pull PWRCNT to high in addition to PWRST driven low. 

To reset the ARM, without reseting the PRTCSS, the following option is available, as taken from section 10.1 of the ARM SS User Guide:

Initiate Watchdog timer reset - Resets all modules including memory, except ARM emulator). emulation.

  The PTRCSS will remain powered until RESETN or ( as named in the PTRCSS User Guide RESETz)

Hi Marcus,

It seems you were cutoff mid-sentence...

Yes, that is exactly what my concern is.  I don't want to lose the timestamp stored in the RTC of the PRTCSS when the ARM is reset. 

I do have PWRCNT pulled high as well, so I believe I should successfully be in external mode for the PRTCSS.

Are you saying that with software I can control whether or not the RTC is reset when the system RESETN is asserted?

Thanks,

-David

Hello David,

Asserting the RESETN signal will reset the RTC and no software control will prohibit the RTC from resetting.  However you can control the reset of the system without affecting

the RTC by a software initiated WDT reset which should reset the system (DM365) but not affect the RTC.

Marcus

Thanks Marcus,

It was that comment you made above that got me wondering if I could avoid loss of RTC data:  Since you're in external mode then you'll need to be sure that the RESETz pin is held high during reset.

But if I understand it correctly then a hard reset (asserting RESETN) will reset the chip entirely, including RTC data.  WE can reclaim the timestamp when the product establishes connection with the host.

Thanks,

-David

hi, Shlomo Kut

How to solve the rtc reset problem, can you help me ?

I use DM36x - EVM - E.

Thanks.

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davinci_rtc_read_time                                                                                      
rtc_davinci rtc_davinci.0: setting system clock to 2000-01-01 00:00:00 UTC (946684800)

Hi Vico,

I'm not sure which issue you're addressing, but we ended up having all reset issues handled by an external MCU.  In fact, all power and resets are handled by the MCU.  It works well and it turns out I"ve come across other DM365 users who have done the same thing.

Regards,

David

Hi, David

Thanks for your reply.

You use normal mode with a MCU control "PRTCSS initialization sequence", right ?

DM365 cannot save timestamp in external mode when  the PRTCSS submodule be battery-powered, right ?

Vico