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I am writing a program to send data from one microcontroller and receive the data using on another PIC32 microcontroller and display the received data on LCD.

I am using UART2 of both PIC32MX to send and receive data and I am using UART interrupt at receiver side. I am not getting any data on receiving side and the LCD display shows nothing. The code is as follows:

The buffer size is 20.

Function to Initialise UART:

void UARTinitialization(void)
{
    PPSUnLock;
    PPSOutput(2, RPC13, U2TX);   // Assign U2TX to pin RPC13
    PPSInput(1, U2RX, RPC14);  // Assign U2RX to pin RPC14
    PPSLock;
    TRISCbits.TRISC14 = 1;
    TRISCbits.TRISC13 = 0;
    U2MODE = 0;

    // enable TX and RX
    U2STA = 0x1400;
    U2BRG = Baud2BRG(115200, pbclk);

    // enable UART2
    IFS1bits.U2RXIF = 0;
    IPC9bits.U2IP = 2;
    IPC9bits.U2IS = 1;
    IEC1bits.U2RXIE = 1;
    U2MODESET = 0x8000;
    rxIndex = 0;

    // RS485                 = READ;
} // END of UART Initialization

Function to display received char:

void Display(void)
{
    if (UART_Flag == 1)         // check whether the program enters into the ISR
    {
      int i;
      for (i=0; i<BUFFER_SIZE; i++)
      {
        LCDinitWriteChar(rxBuffer[i]);
        if (rxBuffer[i] == '\0')
          break;
      }
    UART_Flag = 0;
  }
}

Function to send the data (used at transmitter side):

void writeUART(char *string, size_t size)
{
  while(size > 0)
  {
    while (U2STAbits.UTXBF);

    // put data in to transmit register
    U2TXREG = *string;
    string++;
    size--;
  }
  // wait for complete transmission of data
while(!U2STAbits.TRMT); 
}

ISR code:

void __ISR(_UART_2_VECTOR, IPL6SRS) _U2Interrupt(void)
{
  //Receive Buffer Overrun Error Status bit.
  if (U2STAbits.OERR)
    U2STAbits.OERR = 0;
  else if (IFS1bits.U2RXIF)
  {
    rxBuffer[rxIndex] = U2RXREG;
    // rxIndex++;
    if (rxBuffer[0] != '*')
    {
      rxIndex = 0;
    }
    else
    {
      rxIndex++;
    }
    UART_Flag = 1;
  }
  IFS1bits.U2RXIF = 0;
}

Main function at receiver side:

int main(int argc, char** argv) 
{
  pbclk = SYSTEMConfigPerformance(80000000);
  UARTinitialization();
  LCDInit(); // LCD Intialization
  clearScreen();
  while(1)
  {
    if (U2STAbits.OERR) U2STAbits.OERR = 0;
    if (U2STAbits.PERR) U2STAbits.PERR = 0;
    if (U2STAbits.FERR) U2STAbits.FERR = 0;
    Display();              // function to display received data
    LCDinitClear();
  }
  return (EXIT_SUCCESS);
}
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  • \$\begingroup\$ Are you two in the same class? \$\endgroup\$
    – JRE
    Jan 4, 2019 at 12:31
  • \$\begingroup\$ Specify which chip exactly you are using \$\endgroup\$
    – Damien
    Jan 4, 2019 at 12:41
  • \$\begingroup\$ @JRE thought the same but they are not using the same chip, this one has pin mapping feature and not the other one. \$\endgroup\$
    – Damien
    Jan 4, 2019 at 12:52

1 Answer 1

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Make sure to keep clearing the UART errors from the main while as it can stop the uart:

if (U2STAbits.OERR) U2STAbits.OERR = 0;
if (U2STAbits.PERR) U2STAbits.PERR = 0;
if (U2STAbits.FERR) U2STAbits.FERR = 0;

Where do you call void Display(void) method from ?

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  • \$\begingroup\$ Thanks for your suggestion! Actually i am calling the display function from main() to print the received characters on LCD! \$\endgroup\$ Jan 5, 2019 at 4:10
  • \$\begingroup\$ I have posted main program of receiver in my post! \$\endgroup\$ Jan 5, 2019 at 8:21

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