7profy

SOLVED!
 
Here is solution (for H3):
 
1. Convert script.bin to FEX:
cd /boot bin2fex script.bin script.fex 2. Edit script.fex to enable UART3:
sudo nano script.fex Find section [uart0] and set the next to disable uart0-2 and enable uart3 only with 2-pin mode on pin 8/10:
[uart0] uart_used = 0 uart_port = 0 uart_type = 2 uart_tx = port:PA04<2><1><default><default> uart_rx = port:PA05<2><1><default><default> [uart1] uart_used = 0 uart_port = 1 uart_type = 4 uart_tx = port:PG06<2><1><default><default> uart_rx = port:PG07<2><1><default><default> uart_rts = port:PG08<2><1><default><default> uart_cts = port:PG09<2><1><default><default> [uart2] uart_used = 0 uart_port = 2 uart_type = 4 uart_tx = port:PA00<2><1><default><default> uart_rx = port:PA01<2><1><default><default> uart_rts = port:PA02<2><1><default><default> uart_cts = port:PA03<2><1><default><default> [uart3] uart_used = 1 uart_port = 3 uart_type = 2 uart_tx = port:PA13<2><1><default><default> uart_rx = port:PA14<2><1><default><default> ;uart_rts = port:PA15<3><1><default><default> ;uart_cts = port:PA16<3><1><default><default> Remark: I don't find description for value <2> in PA13<2> but it works as expected.
 
3. Save changes.
 
4. Convert FEX to bin
fex2bin script.fex script.bin 5. Reboot.
 
6. Device name is ttyS3. Default speed = 57600. To test it type "echo TEST > /dev/ttyS3"
 
 
PS. Some times after 
apt-get upgrade script.bin replaces to default values, so it need to repeat all steps.