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LPC4357: how to setting M4 core frequency at most 204MHz?

Question asked by Daniele Fingolo on Mar 6, 2019
Latest reply on Mar 8, 2019 by Daniele Fingolo

I'm trying to implement PLL1 to set the main clock frequency for the M4 core at most 204MHz.
To set the PLL1 with the PLL1_CTRL register there are no problems. I perform the following instructions:
1) Set AUTOBLOCK
2) Set M and N
3) wait LOCK
4) Set DIRECT
5) wait LOCK
6) clear BYPASS
7) wait LOCK

Each setting is set and the LOCK in PLL1_STAT is always 0.
Unfortunately, when I finally select the CLK_SEL of BASE_M4_CLK at 0x9, the next instruction is no longer executed.
Even if I do this last setting before setting up the PLL1, it does the same problem.

What could be the reason?

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