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Wake up from poweroff state using SRTC in i.MX6ULL

Question asked by Vivek Rajpara on Oct 6, 2019
Latest reply on Oct 19, 2019 by igorpadykov



We are keeping our i.MX6ULL based board at  85 °C constant for 16 hours. We observed that after some hours every supply gets down to 0 V i.e. SOC_IN and HIGH_IN goes to 0V, VSNVS is still 3V and PMIC_POWERON_REQ goes low. Hence the pmic goes to power off mode.


Board : i.MX6ULL

External PMIC: PF3001

Linux BSP: 4.9.88_2.0.0


Below is snapshot from i.MX6ULL Reference manual Table 51-3, where it says that if SoC goes OFF then SNVS can generate and alarm and wake the external PMIC. We want to achieve this, as our SoC automatically goes OFF, while we are in u-boot at  85 °C for some hours.



1) In this link one of the NXP member says, i.MX6ULL does not have SNVS RTC module. whereas, this link says that SNVS RTC is present in i.MX6ULL as well but not documented the SNVS LP registers in the Reference Manual. Does i.MX6ULL have SNVS LP registers and SNVS RTC support? One of the NXP engineer mentioned that there will be update in i.MX6ULL Reference Manual, but it has been more than a year and yet no update in the revision of i.MX6ULL Reference Manual. Can you please let us know about the SNVS LP registers details for i.MX6ULL?


2) If SNVS RTC is supported in i.MX6ULL, how to turn ON the SoC from OFF mode using SNVS timer? I tried the unit_tests package in i.MX6ULL EVK for SRTC in the latest BSP and tried running "rtcwakeup.out", and I am able to wakeup from suspend mode. 

However, I applied the below command, which poweroff the whole system. But unable to wakeup using SNVS RTC.

"echo +120 > /sys/class/rtc/rtc0/wakealarm && shutdown -h now"


Can anyone let me know how to wakeup from power off using the SNVS timer alarm as mentioned in the above screenshot? I have the EVK to test so, any verified/proven method for the same will be really helpful.