Peripheral Simulation

For Atmel AT8xC5122 — X2 mode for CPU and each peripheral with Clock Prescaler & PLL Control

Simulation support for this peripheral or feature is comprised of:

• Dialog boxes which display and allow you to change peripheral configuration.
• VTREGs (Virtual Target Registers) which support I/O with the peripheral.

These simulation capabilities are described below.

Clock Control Dialog

PORTx VTREG
Data Type: unsigned char

The PORTx VTREGs represent the I/O pins of the simulated MCU for Port 0, Port 1, and so on. PORT0 represents Port 0, PORT1 represents Port 1, etc. You may read PORTx to determine the state of the output pins of that port. For example, in the command window, you may type,

PORT0

to obtain value corresponding to the set pins of Port 0. You may also change the input values of port pins by changing the value of the VTREG. For example,

PORT1=0xF0

sets the upper four port pins of Port 1 to a value of 1 and the lower 4 port pins to a value of 0. You may use the bitwise operators AND(&), OR(|) and XOR(^) to change individual bits of the PORTx VTREGs. For example:

PORT1 |=  0x01;  /* Set P1.0 Pin */
PORT3 &= ~0x02;  /* Clr P3.1 Pin */
PORT1 ^=  0x80;  /* Toggle P1.7 Pin */

X2 VTREG
Data Type: unsigned char

XTAL_x VTREG
Data Type: unsigned long

The XTAL_x VTREGs (XTAL_A, XTAL_B, XTAL_C) contain the frequency of the oscillator (in Hertz) used to drive the microcontroller. The value is automatically set from the value specified in Project Options - Options for Target. However, you may change the value of XTAL_x using the command window. For example:

XTAL_x = 12000000

You may also output the current value of XTAL_x using the following:

XTAL_x

XTAL_x may be used in calculations to synchronize external scripts with the simulated microcontroller.