Datasheet

User manual Rev. 12.3 — 10 June 2014 67 of 547

NXP Semiconductors

UM10398

Chapter 5: LPC111x/LPC11Cxx Power profiles

For a simplified clock configuration scheme see Figure 12. For more details see Figure 8.

5.7.1.1 Param0: main clock

The main clock is the clock rate the microcontroller uses to source the system’s and the

peripherals’ clock. It is configured by either a successful execution of the clocking routine

call or a similar code provided by the user. This operand must be an integer between 1 to

50 MHz inclusive. If a value out of this range is supplied, set_power returns

PWR_INVALID_FREQ and does not change the power control system.

5.7.1.2 Param1: mode

The input parameter mode (Param1) specifies one of four available power settings. If an

illegal selection is provided, set_power returns PWR_INVALID_MODE and does not

change the power control system.

PWR_DEFAULT keeps the device in a baseline power setting similar to its reset state.

PWR_CPU_PERFORMANCE configures the microcontroller so that it can provide more

processing capability to the application. CPU performance is 30% better than the default

option.

PWR_EFFICIENCY setting was designed to find a balance between active current and

the CPU’s ability to execute code and process data. In this mode the device outperforms

the default mode both in terms of providing higher CPU performance and lowering active

current.

PWR_LOW_CURRENT is intended for those solutions that focus on lowering power

consumption rather than CPU performance.

5.7.1.3 Param2: system clock

The system clock is the clock rate at which the microcontroller core is running when

set_power is called. This parameter is an integer between from 1 and 50 MHz inclusive.

5.7.1.4 Code examples

The following examples illustrate some of the set_power features discussed above.

5.7.1.4.1 Invalid frequency (device maximum clock rate exceeded)

command[0] = 60;

command[1] = PWR_CPU_PERFORMANCE;

command[2] = 60;

(*rom)->pWRD->set_power(command, result);

The above setup would be used in a system running at the main and system clock of

60 MHz, with a need for maximum CPU processing power. Since the specified 60 MHz

clock is above the 50 MHz maximum, set_power returns PWR_INVALID_FREQ in

result[0] without changing anything in the existing power setup.

5.7.1.4.2 An applicable power setup

command[0] = 24;

command[1] = PWR_CPU_EFFICIENCY;

command[2] = 24;