am3358 rtc doesn't work and rtc time is lost

winds2001

Other Parts Discussed in Thread: TPS65910

hi , I design my board by am335x ,i use tps65910 and am3358bzcza100， i use RTC-only mode, i use a 3.3v backup battery to 65910 pin 27 (vbackup), when powered off ,the 65910 pin29 VRTC is 1.8v

i use a 32.768khz crystal ,ENZ_KALDO_1P8 is to gnd , CAP_VDD_RTC connect to 1uf, the rtc design seems to be right.

However, when i powered off ,the rtc time cannot be saved but to be the default time (the 32.768khz crystal is not work when powered off).

does the pmic65910 and cpu rtc registers need to be set?

what can i do?

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

What software are you using?

0 winds2001 over 9 years ago in reply to Biser Gatchev-XID

Intellectual 350 points

i use sdk6.0 from ti

0 winds2001 over 9 years ago in reply to winds2001

Intellectual 350 points

all function of the board is ok except the RTC

0 winds2001 over 9 years ago in reply to winds2001

Intellectual 350 points

if here has a HW engineer , could you tell me when powered off , the vrtc is 1.8v, so the 32.768hz crystal is work or not?

0 Biser Gatchev-XID over 9 years ago in reply to winds2001

TI__Guru**** 393215 points

Please check if your board is properly configured for RTC-only mode as described in this table: processors.wiki.ti.com/.../AM335x_Schematic_Checklist Also check what happens to RTC_PWRONRSTn when power is switched off. If this signal goes low the RTC will be held in reset.

0 winds2001 over 9 years ago in reply to Biser Gatchev-XID

Intellectual 350 points

yes, you are right. i find that the RTC_PWRONRSTn must at least 1ms later than VRTC, when i realize this and then i solve this RTC problem.
thanks

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am3358 rtc doesn't work and rtc time is lost