What is the maximum number of bytes that UART can send at one time?

Is there a maximum number of bytes that Serial.print() can send out at one time through the UART? If yes, what is the maximum? Does it matter whether the UART is hardware or software serial? I am using Atmega328.

Do you mean like this: Serial.print ("just what exactly are the limits of how big of a message I can send out at one time without something or failing to send things out correctly?");

Try it and see.

at any one time the UART can only send 1 byte - in fact one bit :slight_smile:

The internal buffer is default 64 bytes, but during sending you can add more bytes to the buffer as long as you do not exceed 64 bytes in buffer.

robtillaart: ...but during sending you can add more bytes to the buffer as long as you do not exceed 64 bytes in buffer.

... and then it waits (i.e., blocks). It does not return from serial.print until there is room in the buffer.