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8 years, 11 months ago.
ClockFrequency LPC4088 QSB
How do you change the clock frequency from 12MHz to 120MHz? I tried the example from the LPC1768 but that is asking for LPCxx.h and I cannot find the LPC40xxh to change the type of board.
Does anyone know how to change it?
1 Answer
8 years, 11 months ago.
The NXP ARM devices (and also those from other vendors) use a phase locked loop (PLL) to generate the internal clockfrequency from either an internal RC oscillator or from an external clock crystal. The configuration of the PLL has many settings and options which are descibed in the user manual. Many other clocks (eg serial port) are derived from the systemcoreclock. Don't play around with the PLL until you understand how it works cause things could break... The mbed lib calls CMSIS functions to take care of all this for you. Use the following code to check what the current systemclock is.
pc.printf("CPU SystemCoreClock is %d Hz\r\n", SystemCoreClock);