K60P100M100SF2RM Datasheet, PDF (562/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Initialization / Application Information
• When using a 32.768 kHz external reference, if the maximum low-range DCO
frequency that can be achieved with a 32.768 kHz reference is desired, set
C4[DRST_DRS] bits to 2'b00 and set C4[DMX32] bit to 1. The resulting DCO
output (MCGOUTCLK) frequency with the new multiplier of 732 will be 24
MHz.
• When using a 32.768 kHz external reference, if the maximum mid-range DCO
frequency that can be achieved with a 32.768 kHz reference is desired, set
C4[DRST_DRS] bits to 2'b01 and set C4[DMX32] bit to 1. The resulting DCO
output (MCGOUTCLK) frequency with the new multiplier of 1464 will be 48
MHz.
• When using a 32.768 kHz external reference, if the maximum mid high-range
DCO frequency that can be achieved with a 32.768 kHz reference is desired, set
C4[DRST_DRS] bits to 2'b10 and set C4[DMX32] bit to 1. The resulting DCO
output (MCGOUTCLK) frequency with the new multiplier of 2197 will be 72
MHz.
• When using a 32.768 kHz external reference, if the maximum high-range DCO
frequency that can be achieved with a 32.768 kHz reference is desired, set
C4[DRST_DRS] bits to 2'b11 and set C4[DMX32] bit to 1. The resulting DCO
output (MCGOUTCLK) frequency with the new multiplier of 2929 will be 96
MHz.
5. Wait for the FLL lock time to guarantee FLL is running at new C4[DRST_DRS] and
C4[DMX32] programmed frequency.
To change from FEI clock mode to FBI clock mode, follow this procedure:
1. Change C1[CLKS] bits in C1 register to 2'b01 so that the internal reference clock is
selected as the system clock source.
2. Wait for S[CLKST] bits in the MCG status register to change to 2'b01, indicating
that the internal reference clock has been appropriately selected.
3. Write to the C2 register to determine the IRCS output (IRCSCLK) frequency range.
• By default, with C2[IRCS] cleared to 0, the IRCS selected output clock is the
slow internal reference clock (32 kHz IRC). If the faster IRC is desired, set
C2[IRCS] bit to 1 for a IRCS clock derived from the 4 MHz IRC source.
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
562
Freescale Semiconductor, Inc.