MCG_S field descriptions (continued)Field Description4IREFSTInternal Reference StatusThis bit indicates the current source for the FLL reference clock. The IREFST bit does not updateimmediately after a write to the IREFS bit due to internal synchronization between clock domains.0 Source of FLL reference clock is the external reference clock.1 Source of FLL reference clock is the internal reference clock.3–2CLKSTClock Mode StatusThese bits indicate the current clock mode. The CLKST bits do not update immediately after a write to theCLKS bits due to internal synchronization between clock domains.00 Encoding 0 — Output of the FLL is selected (reset default).01 Encoding 1 — Internal reference clock is selected.10 Encoding 2 — External reference clock is selected.11 Reserved.1OSCINIT0OSC InitializationThis bit, which resets to 0, is set to 1 after the initialization cycles of the crystal oscillator clock havecompleted. After being set, the bit is cleared to 0 if the OSC is subsequently disabled. See the OSCmodule's detailed description for more information.0IRCSTInternal Reference Clock StatusThe IRCST bit indicates the current source for the internal reference clock select clock (IRCSCLK). TheIRCST bit does not update immediately after a write to the IRCS bit due to internal synchronizationbetween clock domains. The IRCST bit will only be updated if the internal reference clock is enabled,either by the MCG being in a mode that uses the IRC or by setting the C1[IRCLKEN] bit .0 Source of internal reference clock is the slow clock (32 kHz IRC).1 Source of internal reference clock is the fast clock (4 MHz IRC).24.3.7 MCG Status and Control Register (MCG_SC)Address: 4006_4000h base + 8h offset = 4006_4008hBit 7 6 5 4 3 2 1 0ReadATME ATMSATMFFLTPRSRV FCRDIVLOCS0WriteReset 0 0 0 0 0 0 1 0MCG_SC field descriptionsField Description7ATMEAutomatic Trim Machine EnableEnables the Auto Trim Machine to start automatically trimming the selected Internal Reference Clock.NOTE: ATME deasserts after the Auto Trim Machine has completed trimming all trim bits of the IRCSclock selected by the ATMS bit.Table continues on the next page...Memory Map/Register DefinitionKL04 Sub-Family Reference Manual, Rev. 3.1, November 2012346 Freescale Semiconductor, Inc.
