I am using UART0 port for the normal UART interface and also using it for firmware upgrading via bootloader.
As you see blow, the UART Rx signal is coming through a resistor network to convert from 5V FTDI cable signal to 3.3V level.
Problem is the UART port gets locked up and can’t communicate at all when the operator plugs in the FTDI cable to the board.
When the failure happens, the processor seems still working because the LCD is refreshing every a certain period.
Note :
- The UART0 port is disabled when there is no activity over 2mins
- When the cable plugs in, the RX signal goes high and it wakes up the processor by an interrupt.
Question :
- One possibility is signal overshoots when the FTDI cable plugs in, then a lot of interrupts happens on the UART input port and it causes interrupt buffer overflow.
- In this case, how can the processor detects the UART error and resolve the error condition by firmware?
