When any UART input is high at the powering up stage of the IMXRT1020, seems that the MCU cannot run properly (we cannot see 1.1V supplied by the MCU and nothing works). We observed that issue for these cases:
- When an active (means it drives its tx pin high) UART/RS232 converter is connected to UART1 (debug console) of IMXRT1020
- When we connect RS485 converter to UART2 of IMXRT1020 and the converter drivers rx pin as high
When we isolate those pins, MCU runs perfectly, but when any of them is connected while powering up the MCU, MCU does not work.
We haven't specifically tested all other interfaces, if they have also similar problems. Our problem is on these UART interfaces for now.