(jessie 3.4.112-sun8i)

How to use debug TTL UART(three pins next to the power jack )?

 

 

if you do "cat /proc/cmdline", you will probably see that serial debug is attached as /dev/ttyS0.

if you do "cat /proc/cmdline", you will probably see that serial debug is attached as /dev/ttyS0.

Yes you are right (as I understand it is configured). Now how can I use it using C language or Python.

cat /dev/ttyS0|tee my-data Will it work?

What do you mean ?

 

Do you wish to send something from your C or Python application to this serial output ?

 

Or you wish to see the debug output from the kernel without using a USB-Serial dongle ?

 

For the first case, simply use normal open()/read()/write()/close() APIs, for Python, you need to install python-serial.

 

For the second case, no need to talk to serial, simply look at dmesg and/or /var/log/syslog.