I've a problem with iMX28.
Doing EMC test of my design I discover that iMX28 hangs-up when there are voltage holes in VDD5V, then it goes to a indeterminated state forever.
RESETN line has no effect, it only works again unplugging the power supply and plugging it again.
See the attached image. Yellow line is main Vcc 12V, blue line is 5V that feeds the iMX28.
I can reproduce the hang-up in all my prototipes even in the EVK. It happens at any step: bootlets, kernel linux boot, linux running.
So I can deduce that I can't solve this changing the register configuration. Maybe changing pin configuration???
My design is based on the EVK schematic, but I use VDD5V only, without battery.
I'm not clear about the use and the right connection of BATTERY pin and DCDC_BAT pin in VDD5V only design. The Freescale's docs is not clear about this.
In my design that pins are unconnected.
Using an external watchdog that controls the on/off of the VDD5V maybe works, but that be last action (that makes more expensive my design and imply a re-design)
PD: See the attached pdf for schematic about power-cpu