Peripheral Simulation

For Synopsys DW-8051 — Clock, Timer Rate & External Memory Stretch Control

Simulation support for this peripheral or feature is comprised of:

• Accurate simulation of special on-chip features.
• 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.

MOVX Duration

The feature allows the programmer to adjust the speed of external memory accesses by adding machine cycles the MOVX instruction. Increasing machine cycles lengthens the RD and WR strobe signals for each MOVX instruction executed, thereby allowing access to slower memory or peripherals. The MOVX Duration setting affects the speed of the MOVX instruction only.

Clock Control Dialog

The Clock Generation dialog displays and allows you to specify the configuration for the MCU clock.

Control Register

• CKCON contains the MOVX duration selection setting, as well as the Watchdog Timer mode setting and Timer/Counter Clock selection bits.

Timer Rate Control

• T2M if set, the Timer 2 clock frequency equals the system clock divided by 4. If reset, it equals the system clock divided by 12.
• T1M if set, the Timer 1 clock frequency equals the system clock divided by 4. If reset, it equals the system clock divided by 12.
• T0M if set, the Timer 0 clock frequency equals the system clock divided by 4. If reset, it equals the system clock divided by 12.

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 from the selected oscillator frequency and clock prescaler and PLL settings (if present). The CLOCK VTREG can only be read. It can not be changed directly. It can only be changed by changing the value of the selected oscillator frequency or by changing the clock prescaler or PLL settings (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.