ISD51 User's Guide

Troubleshooting

If the µVision Debugger does not connect to the ISD51 hardware, you should first verify that the target system's serial interface is correctly configured. You may check this with the µVision Simulator as follows:

1. Select Project - Options for Target - Debug: Use Simulator.
2. Start program simulation with Debug - Start/Stop Debug Session. This loads the user program in simulation mode.
3. Start running the user program (Debug - Go).
4. Verify the settings of the UART with the Serial Port Dialog (Peripherals - Serial). The baud rate is displayed correctly if you have entered the correct XTAL frequency in Project - Options for Target - Target - XTAL. Typically, the baud rate does not match the PC baud rate 100%, but it should be within 2%.
5. Check serial communications:
   • Open the serial communication window (View - Serial Window).
   • Right-click in the Serial Window and select Hex Mode from the context menu.
   • Enter sin=0xA5 in the Command Window to Input a 0xA5 character in the serial input stream. This is the debugger signature that ISD51 recognizes as the beginning of a debugger command.
   The µVision Simulator should then simulate the IDS51 interrupt and display 0xF7 followed by six more hex values in the serial window.

If everything is correctly configured and you are still unable to connect to the IDS51 hardware, try invoking the following function after initializing the serial interface.

/*
* Test Function:
* Verify serial communication with HyperTerminal
*/

void TestSerial (void) {
  char c = 'A';

  TI = 1;
  while (1) {
    if (RI) {
      c = SBUF;
      RI = 0;
    }

  while (!TI);

  TI = 0;
  SBUF = c;
  }
}

This function outputs a character via the 8051 on-chip serial port. The character A is transmitted initially. If a character is received on the 8051's serial port, that character is then transmitted.

You may use a terminal program like HyperTerminal to verify that the 8051 transmits the letter A and that other characters you type are echoed.