The CPU clock is determined by the PLL0 parameters in OPBT1. Factory default value is 0xBFFFC938, which cannot be used for Flash programming using UMI.
Similar limitation exists on P1L-C where the OPBT1 factory default value is 0xBFFFC939. Valid value is for example 0xBFFFC938.
P1x-C devices start at full speed from a PLL that's defined by OPBT1. Follow the User's Manual closely. An incorrect setting can make the device inoperable.
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