µVISION DEBUGGER: Using the AINx VTRegs

Information in this article applies to:

• C166 Version 4 and later
• C251 Version 3 and later
• C51 Version 6 and later
• µVision Version 2 and later

QUESTION

What are the AINx VTReg and how do I use it?

ANSWER

When simulating a target microcontroller, the Keil µVision Debugger provides Virtual Target Registers (VTRegs) to allow you to provide input to the pins of the simulated device.

The AINx VTRegs represent the inputs to the analog input pins of the MCU for analog input 0, 1, 2, and so on.

So, if you have configured the analog inputs, the following commands (typed in the debugger Command Window) input the voltages specified.

AIN0 = 0.000  /* Analog Input 0 = 0.000 volts */
AIN1 = 2.500  /* Analog Input 0 = 2.500 volts */
AIN2 = 4.999  /* Analog Input 0 = 4.999 volts */

You may create signal functions that inject waveforms into the analog inputs. For example:

signal void analog0_sine (float limit)  {
  float i;
  float sine;

  printf ("Analog0_sine (%f) entered.\n", limit);

  while (1)  {          /* forever */

    /* SIN swings from -1 to 1 so... adjust it to scale from 0 to 1 */
    /* This is a Taylor series that calculates SIN */
    /* i is the angle where -1.0 = -pi/2 and 1.0 = +pi/2 */

    for (i = -1.0; i < 1.0; i += 0.01) {
      sine = i * (1.570796329
           - i * i * (0.6459640960
           - i * i * (0.07969262599
           - i * i * (0.004681754102
           - i * i * (0.0001604411842)))));
/*      printf ("SIN(%4f) = %6f\n", i * 90.0, sine); */
      ain0 = ((sine + 1.0) / 2.0) * limit;
      twatch (2000000);
    }

    for (i = 1.0; i > -1.0; i -= 0.01) {
      sine = i * (1.570796329
           - i * i * (0.6459640960
           - i * i * (0.07969262599
           - i * i * (0.004681754102
           - i * i * (0.0001604411842)))));
/*      printf ("SIN(%4f) = %6f\n", i * 90.0, sine); */
      ain0 = ((sine + 1.0) / 2.0) * limit;
      twatch (2000000);
    }
  }
}

SEE ALSO

• µVision DEBUGGER: Using the PORTx VTREGs
• µVision DEBUGGER: Using the STIME VTReg
• µVision DEBUGGER: Using The SIN VTREG

Last Reviewed: Thursday, January 7, 2021