I have written a program to transmit some data from serial port 0 in mode 0 and another serial port 1 to recieve in mode 0. I conected two ports so, that the same transmited data can be recieved at another port, but here I observed different data with some symetry input and output like for example

input -03; output - 1f
input 01; output - 0f
input -05; output - 2f
input -09; output - 4f

the above input and output are examples but one thing observed is the output will be same for one particular input.

and here iam not using interrupts but i am doing polling

if (TI != 0)
{
if(RI1 != 0)
{
RI1 =0;
TI = 0;
SBUF0 = EXTAUTODAT1;
EXTAUTODAT2 = SBUF1 ;
}
}

and iam working on cypress ez-usb fx2

Madhu