1、D2 DB_PORST_N pin after Power on Reset caused the system to crash.
There are timing requirements for this pin:
We have not use PORST_N . We use the circuit in the reference design.
2、The boot level of the pin ESW_P3_LED_0 is low, and the level state is different from that of the other four indicator light pins.
It is normal for the pin ESW_P3_LED_0 to have a low on-grid level, because the circuit design is different and the level state is different from that of the other four indicator light pins.
3.Does the 7621A module support RTC? Is there a reference circuit?
The chip does not have RTC function. It can be external to the RTC circuit through the I2C interface. This is a reference circuit I find. You can refer to it.