If it is necessary to keep the MOSC powered on during automatic (deep-sleep) or accidental power
down, then the
MOSCDPD
bit should be set to 0x1. Otherwise, if the
MOSCDPD
bit is set to 0x0, the
MOSC is powered off when deep-sleep is entered or automatic power down occurs. The following
table describes the relationship between the
PWRDN
bit in the
MOSCCTL
register and the
MOSCDPD
bit in the
DSCLKCFG
register:
Table 5-10. MOSC Configurations
Result
MOSCDPD
field
PWRDN
bit
MOSC is powered ON in run and sleep modes, but is disabled in accidental power down,
when the
PWRDN
bit is set in the
MOSCCTL
register, or in deep-sleep mode only if it is not
the deep-sleep clock source (
DSOSCSRC
!==0x3).
0
0
MOSC is powered and running in run, sleep and deep-sleep modes.
1
0
MOSC is powered off, and does not run in any mode. Please note, that in this configuration,
when the MOSC is disabled, the MOSC must not be chosen as a clock source or indeterminate
results occur.
0
1
MOSC runs and does not disable itself in run, sleep, and deep-sleep modes regardless of
the fact that the
PWRDN
bit is set.
1
1
Note:
The
MOSCDPD
bit has an effect in all modes of operation
To change the system clock frequency by changing its corresponding PSYSDIV or OSYSDIV value,
a user must ensure timing parameters to memory are within range through the following steps:
1.
If the change in system clock frequency changes the operational range of the timing parameters,
the
MEMTIM0
register must be updated. If so, write the timing configuration register,
MEMTIM0
,
setting the value to correspond to the final SYSCLK frequency (f
VCO
/new SYSDIV or f
OSC
).
Otherwise the
MEMTIM0
register should not be changed.
2.
Write the
RSCLKCFG
register's
PSYSDIV
value and
MEMTIMU
bit if the
MEMTIM0
register is
updated in the first step. The new SYSDIV is now in effect.
5.4
Register Map
Table 5-11 on page 247 lists the System Control registers, grouped by function. The offset listed is
a hexadecimal increment to the register's address, relative to the System Control base address of
0x400F.E000.
Note:
Spaces in the System Control register space that are not used are reserved for future or
internal use. Software should not modify any reserved memory address.
Additional Flash and ROM registers defined in the System Control register space are
described in the “Internal Memory” on page 600.
Table 5-11. System Control Register Map
See
page
Description
Reset
Type
Name
Offset
Device Identification 0
-
RO
DID0
0x000
Device Identification 1
0x101F.C06E
RO
DID1
0x004
Power-Temp Brown Out Control
0x0000.0003
RW
PTBOCTL
0x038
Raw Interrupt Status
0x0000.0000
RO
RIS
0x050
247
June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller