A/D Converter Simulation

The µVision Debugger simulates the on-chip A/D Converter of most devices. All registers are fully simulated and the analog inputs may be viewed and changed in real-time.

The Analog/Digital Converter dialog box displays and allows you to adjust special function registers as well as the virtual registers associated with the A/D Converter.

The µVision Debugger defines special variables (called virtual target registers) for the analog voltage inputs. You may change the values of these registers to simulate different input voltages—either in the dialog box or on the command line.

For example, the following line:

AN2 = 2.5

when entered in the Command Window sets the Analog Input 0 to 2.5000 volts.

You can create C scripts for the the µVision Debugger that will run in the background while you debug your program. Scripts may be used to change the analog input values and simulate real-world input signals. It is easy to simulate a sine wave input, a triangle wave, and even complex waveforms.

Following is the C script for the triangle wave displayed on the left.

SIGNAL void analog1 (float limit)  {
  float volts;

  printf ("ANALOG0 (%f) ENTERED\n", limit);
  while (1)  {          /* forever */
    volts = 0;
    while (volts <= limit)  {
      an1 = volts;      /* analog input-0 */
      twatch (30000);   /* 30000 Cycles Time-Break */
      volts += 0.05;    /* increase voltage */
    }
    volts = limit - 0.05;
    while (volts >= 0.05)  {
      an1 = volts;
      twatch (30000);   /* 30000 Cycles Time-Break */
      volts -= 0.05;    /* decrease voltage */
    }
  }
}