MC9S08DN60_08 Datasheet, PDF (134/356 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 8 Multi-Purpose Clock Generator (S08MCGV1)
8.3 Register Definition
8.3.1 MCG Control Register 1 (MCGC1)
R
W
Reset:
7
6
CLKS
5
4
3
2
1
0
RDIV
IREFS IRCLKEN IREFSTEN
0
0
0
0
0
1
0
0
Figure 8-3. MCG Control Register 1 (MCGC1)
Table 8-1. MCG Control Register 1 Field Descriptions
Field
Description
7:6
CLKS
Clock Source Select — Selects the system clock source.
00 Encoding 0 — Output of FLL or PLL is selected.
01 Encoding 1 — Internal reference clock is selected.
10 Encoding 2 — External reference clock is selected.
11 Encoding 3 — Reserved, defaults to 00.
5:3
RDIV
Reference Divider — Selects the amount to divide down the reference clock selected by the IREFS bit. If the
FLL is selected, the resulting frequency must be in the range 31.25 kHz to 39.0625 kHz. If the PLL is selected,
the resulting frequency must be in the range 1 MHz to 2 MHz.
000 Encoding 0 — Divides reference clock by 1 (reset default)
001 Encoding 1 — Divides reference clock by 2
010 Encoding 2 — Divides reference clock by 4
011 Encoding 3 — Divides reference clock by 8
100 Encoding 4 — Divides reference clock by 16
101 Encoding 5 — Divides reference clock by 32
110 Encoding 6 — Divides reference clock by 64
111 Encoding 7 — Divides reference clock by 128
2
IREFS
Internal Reference Select — Selects the reference clock source.
1 Internal reference clock selected
0 External reference clock selected
1
Internal Reference Clock Enable — Enables the internal reference clock for use as MCGIRCLK.
IRCLKEN 1 MCGIRCLK active
0 MCGIRCLK inactive
0
IREFSTEN
Internal Reference Stop Enable — Controls whether or not the internal reference clock remains enabled when
the MCG enters stop mode.
1 Internal reference clock stays enabled in stop if IRCLKEN is set or if MCG is in FEI, FBI, or BLPI mode before
entering stop
0 Internal reference clock is disabled in stop
MC9S08DN60 Series Data Sheet, Rev 3
134
Freescale Semiconductor