
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] to 1 for a IRCS clock derived from the 4 MHz IRC source.
25.5.2 Using a 32.768 kHz reference
In FEE and FBE modes, if using a 32.768 kHz external reference, at the default FLL
multiplication factor of 640, the DCO output (MCGFLLCLK) frequency is 20.97 MHz at
low-range.
If C4[DRST_DRS] bits are set to 2'b01, the multiplication factor is doubled to 1280, and
the resulting DCO output frequency is 41.94 MHz at mid-low-range. If C4[DRST_DRS]
bits are set to 2'b10, the multiplication factor is set to 1920, and the resulting DCO output
frequency is 62.91 MHz at mid high-range. If C4[DRST_DRS] bits are set to 2'b11, the
multiplication factor is set to 2560, and the resulting DCO output frequency is 83.89
MHz at high-range.
In FBI and FEI modes, setting C4[DMX32] bit is not recommended. If the internal
reference is trimmed to a frequency above 32.768 kHz, the greater FLL multiplication
factor could potentially push the microcontroller system clock out of specification and
damage the part.
25.5.3 MCG mode switching
When switching between operational modes of the MCG, certain configuration bits must
be changed in order to properly move from one mode to another.
Each time any of these bits are changed (C6[PLLS], C1[IREFS], C1[CLKS], C2[IRCS],
or C2[EREFS], the corresponding bits in the MCG status register (PLLST, IREFST,
CLKST, IRCST, or OSCINIT) must be checked before moving on in the application
software.
Chapter 25 Multipurpose Clock Generator (MCG)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors
567
Содержание K22F series
Страница 2: ...K22F Sub Family Reference Manual Rev 4 08 2016 2 NXP Semiconductors...
Страница 150: ...Private Peripheral Bus PPB memory map K22F Sub Family Reference Manual Rev 4 08 2016 150 NXP Semiconductors...
Страница 168: ...Module clocks K22F Sub Family Reference Manual Rev 4 08 2016 168 NXP Semiconductors...
Страница 198: ...Security Interactions with other Modules K22F Sub Family Reference Manual Rev 4 08 2016 198 NXP Semiconductors...
Страница 258: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 258 NXP Semiconductors...
Страница 292: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 292 NXP Semiconductors...
Страница 398: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 398 NXP Semiconductors...
Страница 628: ...Initialization and application information K22F Sub Family Reference Manual Rev 4 08 2016 628 NXP Semiconductors...
Страница 740: ...Initialization Application Information K22F Sub Family Reference Manual Rev 4 08 2016 740 NXP Semiconductors...
Страница 750: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 750 NXP Semiconductors...
Страница 816: ...Application information K22F Sub Family Reference Manual Rev 4 08 2016 816 NXP Semiconductors...
Страница 866: ...Initialization Application Information K22F Sub Family Reference Manual Rev 4 08 2016 866 NXP Semiconductors...
Страница 890: ...Application information K22F Sub Family Reference Manual Rev 4 08 2016 890 NXP Semiconductors...
Страница 1028: ...Initialization Procedure K22F Sub Family Reference Manual Rev 4 08 2016 1028 NXP Semiconductors...
Страница 1040: ...Example configuration for chained timers K22F Sub Family Reference Manual Rev 4 08 2016 1040 NXP Semiconductors...
Страница 1118: ...Device mode IRC48 operation K22F Sub Family Reference Manual Rev 4 08 2016 1118 NXP Semiconductors...
Страница 1122: ...USB Voltage Regulator Module Signal Descriptions K22F Sub Family Reference Manual Rev 4 08 2016 1122 NXP Semiconductors...
Страница 1180: ...Initialization application information K22F Sub Family Reference Manual Rev 4 08 2016 1180 NXP Semiconductors...
Страница 1302: ...Application information K22F Sub Family Reference Manual Rev 4 08 2016 1302 NXP Semiconductors...
Страница 1374: ...Functional description K22F Sub Family Reference Manual Rev 4 08 2016 1374 NXP Semiconductors...