Datasheet

User manual Rev. 12.3 — 10 June 2014 65 of 547

NXP Semiconductors

UM10398

Chapter 5: LPC111x/LPC11Cxx Power profiles

5.6.1.4.4 System clock less than or equal to the expected value

command[0] = 12000;

command[1] = 25000;

command[2] = CPU_FREQ_LTE;

command[3] = 0;

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

The above code specifies a 12 MHz PLL input clock, a system clock of no more than

25 MHz and no locking time-out. set_pll returns PLL_CMD_SUCCESS in result[0] and

24000 in result[1]. The new system clock is 24 MHz.

5.6.1.4.5 System clock greater than or equal to the expected value

command[0] = 12000;

command[1] = 25000;

command[2] = CPU_FREQ_GTE;

command[3] = 0;

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

The above code specifies a 12 MHz PLL input clock, a system clock of at least 25 MHz

and no locking time-out. set_pll returns PLL_CMD_SUCCESS in result[0] and 36000 in

result[1]. The new system clock is 36 MHz.

5.6.1.4.6 System clock approximately equal to the expected value

command[0] = 12000;

command[1] = 16500;

command[2] = CPU_FREQ_APPROX;

command[3] = 0;

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

The above code specifies a 12 MHz PLL input clock, a system clock of approximately

16.5 MHz and no locking time-out. set_pll returns PLL_CMD_SUCCESS in result[0] and

16000 in result[1]. The new system clock is 16 MHz.

5.7 Power routine

5.7.1 set_power

This routine configures the device’s internal power control settings according to the calling

arguments. The goal is to reduce active power consumption while maintaining the feature

of interest to the application close to its optimum.

Remark: The set_power routine was designed for systems employing the configuration of

SYSAHBCLKDIV = 1 (System clock divider register, see Table 20

and Figure 12). Using

this routine in an application with the system clock divider not equal to 1 might not improve

microcontroller’s performance as much as in setups when the main clock and the system

clock are running at the same rate.

set_power returns a result code that reports whether the power setting was successfully

changed or not.