MCG_S field descriptions (continued)
Field
Description
4
IREFST
Internal Reference Status
This bit indicates the current source for the FLL reference clock. The IREFST bit does not update
immediately 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.
3–2
CLKST
Clock Mode Status
These bits indicate the current clock mode. The CLKST bits do not update immediately after a write to the
CLKS 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.
1
OSCINIT0
OSC Initialization
This bit, which resets to 0, is set to 1 after the initialization cycles of the crystal oscillator clock have
completed. After being set, the bit is cleared to 0 if the OSC is subsequently disabled. See the OSC
module's detailed description for more information.
0
IRCST
Internal Reference Clock Status
The IRCST bit indicates the current source for the internal reference clock select clock (IRCSCLK). The
IRCST bit does not update immediately after a write to the IRCS bit due to internal synchronization
between 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).
21.3.7 MCG Status and Control Register (MCG_SC)
Address: 4006_4000h base + 8h offset = 4006_4008h
Bit
7
6
5
4
3
2
1
0
Read
Write
Reset
0
0
0
0
0
0
1
0
MCG_SC field descriptions
Field
Description
7
ATME
Automatic Trim Machine Enable
Enables 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 IRCS
clock selected by the ATMS bit.
Table continues on the next page...
Memory Map/Register Definition
KL02 Sub-Family Reference Manual, Rev. 2.1, July 2013
272
Freescale Semiconductor, Inc.