After UART send the bytes from the buffer, \0 is also received.

[RPG]

Why I get \0 at the end of the transmission?

I imaging the \0 is a NUL termination character but I have seen from the terminal that sometimes is not received or arrives with a big delay.

Could somebody tell me anything about it?

Thanks in advance.

[gbm]

The UART sends exactly what you order it to send. Check your code.

[Tesla DeLorean]

Hard to say, use strlen() not sizeof() for strings passed to the output routines, the latter with describe/include the trailing NUL too.

The TX pin should normally be HIGH between transmissions.

[RPG]

The code I saw from the previous developer is using the registers to send the content of the buffer. In the buffer there is no \0.

[Piranha]

Probably the receiver has no pull-up on it's Rx line and, when the MCU releases the Tx pin, the whole line is floating. If the line goes low, such a situation could be interpreted as a start bit + 0x00 data byte. You can test/solve it by enabling a pull-up on MCU's Tx pin.

And yes - you need to understand why the original code disabled the transmitter at all.

[RPG]

Thank you Piranha. This made it work. I have learnt A lot fro this issue.

I changed the TX pin to pull-up and now is working fine.