Device Database®

Peripheral Simulation

For NXP (founded by Philips) P89LPC9331 — CPU Clock Output

Simulation support for this peripheral or feature is comprised of:

• VTREGs (Virtual Target Registers) which support I/O with the peripheral.

These simulation capabilities are described below.

CLOCK VTREG
Data Type: unsigned long

The CLOCK VTREG contains the speed of the microcontroller instruction clock (in Hertz). This is effectively the number of 1-cycle instructions that the simulated microcontroller can execute each second. This number is derived by dividing the oscillator frequency (specified by the XTAL VTREG) by a fixed number (12 on standard 8051 devices). The CLOCK VTREG can only be read. It can be changed directly. It can only be changed by changing the value of the XTAL VTREG or by changing the clock divisor (which is not available on all devices).

XTAL VTREG
Data Type: unsigned long

The XTAL VTREG contains 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 using the command window. For example:

XTAL=12000000

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

XTAL

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