How to avoid garbage values received in UART communication

Question

I am new to the embedded programming. I am doing a UART communication in PIC32MX795F512L MCU. I have somehow managed to transmit and receive data but not able to receive complete string.

I am doing something like this:

char Rx[5] ; //variable to store rx data
int i;
for(i=0;i<=4;i++) 
{
 while(!DataRdyUART1()); //This check if data is ready to be received
 Rx[i] = getcUART1(); //This get one character from UART
 }
 putsUART1(Rx); //Putting all the Rx data on UART

But whats happening is If I type 12345 then I get 123452345&+ its taking the last values. Again if I type asdfg then I get asdfg2345&+. After the 5th character, its showing some garbage values.

This should not happen. I don't know why its taking up 2345&+. How can I remove this. Please help. Thanks.!

• Paebbels: This is a classic buffer overflow...
• Lundin: @Paebbels No, it is a classic "the programmer has not grasped string null termination" beginner bug...

Answer 1

The string needs to be zero terminated so that the sending function, putsUART1, knows when it's reached the end. So make your array one character larger and add a null (zero) at the end.

Something like this:

char Rx[6] ; //variable to store rx data
int i;
for(i=0;i<=4;i++) 
{
 while(!DataRdyUART1()); //This check if data is ready to be received
 Rx[i] = getcUART1(); //This get one character from UART
 }
Rx[5] = 0; // add null terminator
putsUART1(Rx); //Putting all the Rx data on UART