MCXA153 SystemCoreClock default value

HugoArends — Sun, 15 Mar 2026 09:15:19 GMT

Intro

After a reset, he MCXA153 microcontroller runs ate 48MHz, because:

After reset, SCS bits in SCG->CSR = [011] : FIRC
After reset, FIRC (fro_hf) = 48 MHz, as stated in Reference Manual paragraph 21.2 (Rev. 7, 2024-10-22)
After reset, DIV bits in AHBCLKDIV = [00000000] : prescaler = 1

Problem

In the MCUXpresso SDK (26_03_00_pvw1), the SystemCoreClock global variable is configured in the function SystemCoreClockUpdate() in the file system_MCXA153.c. This is correct if the fsl_clock driver is used. If this driver is not used, the SystemCoreClock variable is set to 12MHz, which is not correct.

As a suggestion, update the following

In the file system_MCXA153.h, update the define:

#define DEFAULT_SYSTEM_CLOCK 12000000u /* Default System clock value */

#define DEFAULT_SYSTEM_CLOCK 48000000u /* Default System clock value */

In the file system_MCXA153.c, update the function SystemCoreClockUpdate() so it does not depend on the fsl_clock driver anymore and uses direct register access.

Re: MCXA153 SystemCoreClock default value

Alice_Yang — Mon, 16 Mar 2026 10:37:54 GMT

Hello @HugoArends

Thanks for your suggestion. I will report it to your internal team.

Thank you.

Alice

topic MCXA153 SystemCoreClock default value in MCX Microcontrollers

MCXA153 SystemCoreClock default value

Re: MCXA153 SystemCoreClock default value