I have a custom gateway using the i.MX28 MCU with both 5V and battery power supply.
The board is running a custom uBoot+Linux solution based on buildroot with our own kernel module to control charging and 5V<->battery transitions.
Also we have a user space application to monitor battery voltage, battery voltage maintenance and shutdown on low battery. The user space application will regularly check the battery voltage from the LRADC and keep it between 3.8 and 4.1V according to battery and application specific specs.
It all seems to works fine but I've received reports of situations where boards with 5V power supply attached where the battery voltage drops like the battery is not being charged.The battery charging works fine again if the gateway is power cycled.
I've validated the state of the relevant registers without finding any clues of what has happened.
I've made a script to dump all the PMU related registers on a gateway with and without the issue - both running the same software.There are very little differences except for the BATT_BO bit being set.
If you can think of anything that could explain the behaviour I will be grateful.
Is there anything that can shut of the charger except the PWD_BATTCHRG bit?