Combining Atmega microcontroller with other circuit elements

Hi dear enthusiasts :),
I am transmitting serial data from an external device to one of the serial ports (Serial port 1) of an Arduino Mega. The data goes through a MAX232 chip to convert RS-232 voltage levels to TTL. I have an Xbee connected to another serial port (Serial port 0) of the Mega using an Xbee shield. The serial data transmitted from the external device is wirelessly transmitted to a monitoring station through the Xbee. The Mega here basically works as an intermediate device just for sending the serial data using the following code:

void setup()
  // Initiate serial ports


void loop()
  // Check and if any data is available in the serial buffer, write it to the serial port



I was wondering if I want to put all of that circuitry together and form on circuit, do I still need an Atmega microcontroller. I am asking this because what I using the Mega for is really basic and I was wondering if I am to design a circuit board and put everything together, I could use a chip(s) just to transmit the serial data. Is there more to what the microcontroller doing when transmitting data that cannot be accomplished by something with a more limited functionality? I hope I have clarified myself enough, otherwise please let me know to clarify further. :smiley:

You can connect an XBee directly to the MAX232.
I'm not sure that all XBee work without the need to initialize it at power on, but the normal ones do.

Thanks a lot. I will have a go at it. :smiley: