BL4S200 RS232 port F crashed

I had a problem with the PORT F after a surtension on a lcd display.
The port E is used so i need an other port RS232
There is an extension for the BL4s200 for new port RS232

Thanck you for the help

The BL4S200 only has two RS232 serial ports (E and F), but looking at the BLxS2xx schematic, it appears that you can use serial port B in SPI mode over the same lines (TXE, TXF, RXE). Doing so would interfere with using serial port E on those pins.

How did you damage serial port F? It seems odd that serial port E works when both ports use the same transceiver (U20) for I/O. Maybe you could replace U20 to restore functionality to serial port F?

Serial port C is RS485. Serial port D is (I believe) RS422 signaling (or some sort of differential SPI) running on J6 and J8.

Thanks for your response

I replace with this BL4S200 an BL2665 very old ( 2007)
On this BL2665 i have problem for load the program.

On the BL4S200 i use the port E for a GSM modem and the port F for a lcd display.
The dispay is supply at 5Vcc by a 7805 regulator.
So the regulator crashed and the port F don’t work.

I don’t see the U20 on the card but i suspect it’s a CMS and it’s difficult to change.

So i look for the SPI mode .

Thanck you Alain Rizzo