AM335x RTC Issue

Vishnu Harihar1

Other Parts Discussed in Thread: AM3354

Hi There,

We are using AM3354 rev1 processor in our module. We found that the internal RTC of the processor is not updated by switching off the supply (coin cell as a backup). It's maintaining the same time at power off, but not the updated time.

RTC section is powered from an external LDO and using an external crystal for RTC clock. With the main supply it's running fine, but in RTC backup battery only mode it's not working.

Any help will be appreciated.

Thanks

Vishnu

over 11 years ago

0 Biser Gatchev-XID over 11 years ago

TI__Guru**** 393215 points

Hi Vishnu,

What software are you running? What is the state of RTC_PWRONRSTn in RTC-only mode?

0 Vishnu Harihar1 over 11 years ago in reply to Biser Gatchev-XID

Prodigy 245 points

Hello Biser,

We are running Arago Linux 3.2.

RTC_PWRONRSTn is connected to the same rail of RTC section's power, ie 1.8V LDO's o/p.

Regards

Vishnu

0 Biser Gatchev-XID over 11 years ago in reply to Vishnu Harihar1

TI__Guru**** 393215 points

If you have an external RTC crystal do you see it oscillate in RTC-only mode?

0 Vishnu Harihar1 over 11 years ago in reply to Biser Gatchev-XID

Prodigy 245 points

Yes Biser, it is oscillating and giving 32.7 KHz clock in RTC backup battery only mode.

0 Miroslav Kiradzhiyski XID over 11 years ago in reply to Vishnu Harihar1

TI__Mastermind 25235 points

Hi Vishnu,

The script that handles the system and hardware clocks is /etc/init.d/hwclock.sh. It is run at system INIT, as well as system shutdown. You can also call it to reload/restart the clock, etc.

There is a $VERBOSE variable inside the script. Please set it to "yes" in order to receive verbose output from the script and check what exactly is happening during system init or shutdown.

Best regards,
Miroslav

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AM335x RTC Issue