Clocks and Power Control
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
14-19
This register is affected by HRESET but is not affected by SRESET.
Table 14-8
describes SCCR fields.
Table 14-8. SCCR Field Descriptions
Bits Name
Description
0
—
Reserved, should be cleared.
1–2
COM
Clock output module. This field controls the output buffer of the CLKOUT pin. When both bits are
set, the CLKOUT pin is held in the high state. These bits can be dynamically changed without
generating spikes on the CLKOUT pin. If the CLKOUT pin is not connected to external circuits,
clock output should be disabled to minimize noise and power dissipation. The COM field is cleared
by hard reset.
00 Clock output enabled full-strength buffer.
01 Reserved.
10 Reserved.
11 Clock output disabled.
3–5
—
Reserved, should be cleared.
6
TBS
Timebase source. Determines the clock source that drives the timebase and decrementer.
0 Timebase frequency source is the OSCLK divided by 4 or 16.
1 Timebase frequency source is GCLK2 divided by 16.
7
PTDIV
Periodic interrupt timer clock divide. Determines if the clock, the crystal oscillator, or main clock
oscillator to the periodic interrupt timer is divided by 4 or 512. At power-on reset this bit is cleared
if the MODCK1 and MODCK2 signals are low.
0 The clock is divided by 4.
1 The clock is divided by 512.
8
PTSEL
Periodic interrupt timer select. Selects the crystal oscillator or main clock oscillator as the input
source to PITCLK. At power-on reset, it reflects the value of MODCK1.
0 OSCM (crystal oscillator) is selected.
1 EXTCLK is selected.
9
CRQEN
CPM request enable. Cleared by power-on or hard reset. In low-power modes, specifies if the
general system clock returns to high frequency while the CP is active.
0 The system remains in low frequency even if the communication processor module is active.
1 The system switches to high frequency when the communication processor module is active.
10
–
Reserved, should be cleared
11–12
—
Reserved, should be cleared.
13–14
EBDF
External bus division factor. This field defines the frequency division factor between GCLK
x and
GCLK
x_50. CLKOUT is similar to GCLK2_50. The GCLKx_50 is used by the bus interface and
memory controller to interface with an external system. This field is initialized during hard reset
using the hard reset configuration word in
Section 11.3.1.1, “Hard Reset Configuration Word
.”
00 CLKOUT is GCLK2 divided by 1.
01 CLKOUT is GCLK2 divided by 2.
10 Reserved.
11 Reserved.
15–16
—
Reserved, should be cleared.
Summary of Contents for PowerQUICC MPC870
Page 98: ...MPC885 PowerQUICC Family Reference Manual Rev 2 I 4 Freescale Semiconductor ...
Page 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Page 288: ...MPC885 PowerQUICC Family Reference Manual Rev 2 III 4 Freescale Semiconductor ...
Page 554: ...MPC885 PowerQUICC Family Reference Manual Rev 2 V 6 Freescale Semiconductor ...
Page 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
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Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Page 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...