AM4379: RTC is not retained

Sh.Sasaki

Guru 13625 points

Part Number: AM4379
Other Parts Discussed in Thread: TMDXSK437X, TPS65218

Hi all,

I'd like to keep RTC.

My hardware has the following configuration.

EVM:TMDXSK437X
Connect battery to J3 of EVM

My software has the following configuration.

PROCESSOR-SDK-LINUX-RT-AM437X _03_03_00_04
Set the status register's FSEAL bit in TPS65218 to "1" via I2C.

I executed the following command for RTC test.

I check the time with the Linux hwclk command.

~#hwclock
Web Dec 14 23:26:29 2016 0.000000 seconds

Removing and inserting the AC adapter to perform RTC holding test with battery.
Then I check the time with the Linux hwclk command again.

~#hwclock
Web Dec 14 23:24:17 2016 0.000000 seconds

RTC should be kept by the battery, but time is back.

Do you know why RTC is not kept?

Best regards,
Sasaki

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Hi,

Have you tried:

1. At kernel prompt set the system date and time:
date MMDDhhmmYYYY

2. Update the RTC:
hwclock -w

3. Read the RTC:
hwclock -r

0 Sh.Sasaki over 8 years ago in reply to Biser Gatchev-XID

Guru 13625 points

Hi Biser-san,

Thank you for your reply.

I 'd like to confirm that the AM437x RTC is keeping time during battery operation.

I think that the procedure taught is a way to rewrite RTC.

So, please teach me about the following.

Does the hwclk command read the RTC time in AM437x?
If not, what is the reference time output by hwclk?

Best regards,

Sasaki

0 Sh.Sasaki over 8 years ago in reply to Biser Gatchev-XID

Guru 13625 points

Hi Biser-san,

I verified the operation again, and kept RTC.
Probably I could not keep it because V1_8 VAT was unstable.
I'm sorry to disturb you.

Best regards,

Processors

Processors forum

AM4379: RTC is not retained