Peripheral Simulation

For NXP (founded by Philips) LPC2470 — Clock Source & Dividers

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 Dividers Dialog

The Clock Dividers dialog displays the registers and settings for the CPU and Peripheral clock supported by this device. The Peripheral Clock list allows you to specify a different clock divider for each peripheral.

CPU Clock Configuration

• CCLKCFG (CPU Clock Configuration Register) contains the 8-bit divisor used to create the CCLK signal from the PLL output.
• CCLKSEL (CPU Clock Configuration Selection) holds the 8-bit divisor value used to create the CCLK signal from the PLL output.
• CCLK (CPU Clock) displays the resulting CPU clock value in MHz.

USB Clock Configuration

• USBCLKCFG (USB Clock Configuration Register) contains the 4-bit divisor used to create the USBCLK signal from the PLL output.
• USBSEL (USB Clock Configuration Selection) holds the 4-bit divisor value used to create the USBCLK signal from the PLL output.
• USBCLK (USB Clock) displays the resulting USB clock value in MHz.

Clock Source Dialog

The Clock Source dialog selects the source of the input clocking to the PLL.

Clock Source Select

• CLKSRCSEL (Clock Source Select Register) contains the 2-bit selectiong value.
• CLKSRC (Clock Source Selection) reflects the setting the the CLKSRCSEL register.
• Oscillators (XTAL, IRC and RTCX) text boxes allow you to change the frequency of a clock source.

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. CLOCK is a read-only VTREG. It may not be changed directly. It changes when the value of the XTAL VTREG or the clock divisor (which is not available on all devices) changes.

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=33000000

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.