I have problem with RESETN and i.mx28. I use VDD5V power supply only.
i use external watchdog IC for generate RESETN signal. For test i am not refresh wdg and after some good reboots(10-50) my i.mx28 go to hang state.
vddxtal - 0.97
dcdc_vddio_3v3 - 3.0
vdd4p2 - 0.3V
dcdc_vddd_1v2 - 1.0V
dcdc_vdda_1v8 - 0.96
Clock on 24Mhz - are present.
and only one way to out from this hang state - remove power and apply it again.
I use boot from NAND flash and then "hang" happend i cant see any chip selects signal GPMI_CS0.
and in debug serial not any debug info.
Is this possible that internal bootloader are "hang"? Where i can see bootloader code for understand why boot stopped.
Is this possible that internal LDO (VDD5V to VDD4P2) go to current limit state? But why reasserting RESETN not restore it.
On my board i supply only DDR, NAND and i.mx from internal i.mx power sources.
Why on i.mx28 EVK added MOSFET for break VDD5V then reset button pressed?