How to configure for external HXT source?

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Posts: 3
Joined: 07 Jun 2019, 15:45

07 Jun 2019, 20:52


I need to clock my M484 with an external 12MHz clock source, instead of a 12MHz crystal. I tried the settings as in the RM: programmed '0' to CONIFIG0[27] (FMC) and SYS->GPF_MFPL &= ~(SYS_GPF_MFPL_PF2MFP_Msk | SYS_GPF_MFPL_PF3MFP_Msk) to set the GPIO mode. However, at the clock init stage the CLK->STATUS never indicates the HTX stable, also when trying to enable HSUSBD PHY (HSUSBD_Open()), it dead loops forever.

The 12MHz has been check clean with a DSO and if I bypass the CLK->STATUS the 192MHz PLL seems to work ok by an LED flashing test, although the HSUSBD still refuses to work.

Any clue? or better a sample code supporting the "external clock mode"?



Dylan Hsieh
Posts: 31
Joined: 22 Mar 2017, 09:54

10 Jun 2019, 10:13

Hi David,

Please enable the CKO (clock output) function to check the HXT is fine or not.

We have a sample code which shows how to use the external clock as HXT clock source, but the readme file is written by Chinese: ... 1219135320


Posts: 3
Joined: 07 Jun 2019, 15:45

13 Jun 2019, 06:39

I confirm that the problem has been solved with the instructions in the readme doc. Many thanks.

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