TM4C129XKCZAD Datasheet, PDF (590/2188 Pages) Texas Instruments – Tiva Microcontroller

Hibernation Module
Bit/Field
30
29:20
19
18
17
16
590
Name
RETCLR
reserved
OSCSEL
reserved
OSCDRV
OSCBYP
Type
RW
RO
RW
RO
RW
RW
Reset
0
Description
GPIO Retention/Clear
This bit is used when the VDD3ON bit is set.This bit is must be set when
entering the hibernate state when the VDD3ON bit is set. This does not
affect behavior when VDD3ON is clear.
Note: This bit must be set when enabling VDD3ON mode.
Value Description
0 GPIO retention is released when power is reapplied. The GPIOs
are initialized to default values.
1 GPIO retention set until software clears this bit.
0
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
0
Oscillator Select
This bit is used to select between the use of an external 32.768-kHz
source or the HIB internal low frequency oscillator (HIB LFIOSC).
Note:
To enable the HIB LFIOSC, CLK32EN must be programmed
to 1 at the same time the OSCSEL bit is set. Thus the HIBCTL
register should be written with 0x0008.0040
Value Description
0 External 32.786-kHZ clock source is enabled.
1 HIB Low frequency oscillator (HIB LFIOSC) is enabled.
Note:
The HIB low-frequency oscillator has a wide frequency
variation, therefore the RTC is not accurate when using this
clock source.
0
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
0
Oscillator Drive Capability
This bit is used to compensate for larger or smaller filtering capacitors.
Note:
This bit is not meant to be changed once the Hibernation
oscillator has started. Oscillator stability is not guaranteed if
the user changes this value after the oscillator is running.
Value Description
0 Low drive strength is enabled, 12 pF.
1 High drive strength is enabled, 24 pF.
0
Oscillator Bypass
Value Description
0 The internal 32.768-kHz Hibernation oscillator is enabled. This
bit should be cleared when using an external 32.768-kHz crystal.
1 The internal 32.768-kHz Hibernation oscillator is disabled and
powered down. This bit should be set when using a single-ended
oscillator attached to XOSC0.
Texas Instruments-Production Data
June 18, 2014