NXP Semiconductors LPC84x, Руководство пользователя

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User manual Rev. 1.0 — 16 June 2017 125 of 515
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Chapter 9: LPC84x FRO API ROM routine
9.4 API description
The FRO API provides a function to configure the fro_oscout. The FRO API can be called
in the application code through a simple API call. An example is provided with the code
bundle software package on nxp.com.
The following function prototypes are used:
9.4.1 set_fro_frequency
This routine sets up the required fro_oscout (30 MHz/24 MHz/18 MHz). The requested
frequency is set up and the appropriate factory trim value is used.
See Figure 8 “Clock generation (continued)” and Section 6.5.77 “FRO Control register” .
for more details to select fro_oscout (30/24/18 MHz) or select divided fro_oscout
(1.125 MHz, 1.5 MHz, 1.875 MHz, 9 MHz, 12 MHz, or 15 MHz) based on FAIM low power
boot value.
Table 177 shows the set_fro_frequency routine.
9.4.1.1 Param0: frequency
The frequency is the required fro_oscout, 30 MHz, 24 MHz or 18 MHz.
Table 176. FRO API call
Function prototype API description Reference
void set_fro_frequency(uint32_t iFreq);
Setup the fro_oscout to either 30 MHz, 24 MHz or 18 MHz. 9.4.1
Table 177. set_fro_frequency routine
Routine sidiv
Prototype void set_fro_frequency(uint32_t iFreq);
Input parameter
Param0 —
Required frequency (in kHz). Example: parameter 1: 18000 =>
18MHz, 24000=>24Mhz, 30000=>30Mhz.
Return None.
Description Setup the fro_oscout to either 30 MHz, 24 MHz or 18 MHz.