Hi NXP team,
We have designed custom board based on i.MX6SX processor and used coin cell for the RTC functionality and its power is connected with LICELL Power rail of the PMIC to work the i.MX6SX RTC as per IMX6SOLOX_SABRESDB-DESIGNFILES.(attached image)
Currently we are in the testing stage and we encountered a relatively serious issue with the real-time clock battery. Something with the battery or the clock setting is preventing the board from powering up on subsequent boots. Here are the steps we performed:
(1) With the board powered off, we inserted a CR2032 battery into the BT1 holder. The battery cell was placed face-up, consistent with pin 1 being + and pin 2 being GND.
(2) Power was applied to the board, and the system booted up.
(3) After bootup, the date and time were set using the Linux "date -s" command. Then, the hardware clock was set to mirror the system clock by running "hwclock -u -w".
(4) The board was powered off by executing the "halt" or "poweroff" command.
(5) After everything had halted or powered off, the power connection was removed from the board.
(6) We waited 5-10 minutes, then re-connected the board to power and tried to boot it up. But, the board never successfully booted up due to PMIC_ON_REQ not going from i.MX6SX to PMIC to turn on PMIC outputs.
We tried applying power to boot up multiple times, but it was never successful until we removed the battery. After removing the battery and re-applying power, the board booted up fine.
The same scenario we applied on the IMX6SOLOX_SABRESDB and facing the same issue.
Is there are any specific register settings required in LP section of the RTC to Generate PMIC_ON_REQ to again power up the board?
Please suggest the solution.
If the output from the PMIC has been configured properly and the output to the corresponding rail was properly enabled, then it will be helpful to please refer to the Reference Manual of the i.MX6SX, specifically to chapters related to the RTC, such as 58.8.1 for the RTC control bits setting and 58.8.2 for the RTC value read to double-check the RTC settings: https://www.nxp.com/webapp/Download?colCode=IMX6SXRM
Hope it helps!