The MCUXpresso SDK provides a peripheral clock driver for the SYSCON module of MCUXpresso SDK devices.

Function description

Clock driver provides these functions:

Functions to initialize the Core clock to given frequency
Functions to configure the clock selection muxes.
Functions to setup peripheral clock dividers
Functions to set the flash wait states for the input freuqency
Functions to get the frequency of the selected clock
Functions to set PLL frequency

SYSCON Clock frequency functions

SYSCON clock module provides clocks, such as MCLKCLK, ADCCLK, DMICCLK, MCGFLLCLK, FXCOMCLK, WDTOSC, RTCOSC, USBCLK, and SYSPLL. The functions CLOCK_EnableClock() and CLOCK_DisableClock() enables and disables the various clocks. CLOCK_SetupFROClocking() initializes the FRO to 12 MHz, 48 MHz, or 96 MHz frequency. CLOCK_SetupPLLData(), CLOCK_SetupSystemPLLPrec(), and CLOCK_SetPLLFreq() functions are used to setup the PLL. The SYSCON clock driver provides functions to get the frequency of these clocks, such as CLOCK_GetFreq(), CLOCK_GetFro12MFreq(), CLOCK_GetExtClkFreq(), CLOCK_GetWdtOscFreq(), CLOCK_GetFroHfFreq(), CLOCK_GetPllOutFreq(), CLOCK_GetOsc32KFreq(), CLOCK_GetCoreSysClkFreq(), CLOCK_GetI2SMClkFreq(), CLOCK_GetFlexCommClkFreq, and CLOCK_GetAsyncApbClkFreq.

SYSCON clock Selection Muxes

The SYSCON clock driver provides the function to configure the clock selected. The function CLOCK_AttachClk() is implemented for this. The function selects the clock source for a particular peripheral like MAINCLK, DMIC, FLEXCOMM, USB, ADC, and PLL.

SYSCON clock dividers

The SYSCON clock module provides the function to setup the peripheral clock dividers. The function CLOCK_SetClkDiv() configures the CLKDIV registers for various periperals like USB, DMIC, I2S, SYSTICK, AHB, ADC, and also CLKOUT and TRACE functions.

SYSCON flash wait states

The SYSCON clock driver provides the function CLOCK_SetFLASHAccessCyclesForFreq() that configures FLASHCFG register with a selected FLASHTIM value.

Typical use case

POWER_DisablePD(kPDRUNCFG_PD_FRO_EN); /*!< Ensure FRO is on so that we can switch to its 12MHz mode temporarily