3.
The internal reset is released and the microcontroller fetches and loads the initial stack pointer,
the initial program counter, the first instruction designated by the program counter, and begins
execution.
The result of a brown-out reset is equivalent to that of an assertion of the external
RST
input, and
the reset is held active until the proper voltage level is restored. The
RESC
register can be examined
in the reset interrupt handler to determine if a Brown-Out condition was the cause of the reset, thus
allowing software to determine what actions are required to recover.
The internal Brown-Out Reset timing is shown in “Power and Brown-Out” on page 1826.
5.2.2.6
Software Reset
Software can reset a specific peripheral or generate a reset to the entire microcontroller.
Peripherals can be individually reset by software via peripheral-specific reset registers available
beginning at System Control offset 0x500 (for example the
Watchdog Timer Software Reset
(SRWD)
register page 354). If the bit position corresponding to a peripheral is set and subsequently
cleared, the peripheral is reset.
The entire microcontroller, including the core, can be reset by software by setting the
SYSRESREQ
bit in the
Application Interrupt and Reset Control (APINT)
register in the core peripheral memory
map space. The software-initiated system reset sequence is as follows:
1.
A software microcontroller reset is initiated by setting the
SYSRESREQ
bit.
2.
An internal reset is asserted.
3.
The internal reset is deasserted and the microcontroller loads from memory the initial stack
pointer, the initial program counter, and the first instruction designated by the program counter,
and then begins execution.
The core only can be reset by software by setting the
VECTRESET
bit in the
APINT
register. The
software-initiated core reset sequence is as follows:
1.
A core reset is initiated by setting the
VECTRESET
bit.
2.
An internal reset is asserted.
3.
The internal reset is deasserted and the microcontroller loads from memory the initial stack
pointer, the initial program counter, and the first instruction designated by the program counter,
and then begins execution.
The software-initiated system reset timing is shown in Figure 27-12 on page 1832.
5.2.2.7
Watchdog Timer Reset
The Watchdog Timer module's function is to prevent system hangs. The TM4C1294NCPDT
microcontroller has two Watchdog Timer modules in case one watchdog clock source fails. One
watchdog is run off the system clock and the other is run off the Precision Internal Oscillator (PIOSC).
The watchdog timer can be configured to generate an interrupt or a non-maskable interrupt to the
microcontroller on its first time-out and to generate a system reset or power-on reset on its second
time-out.
After the watchdog's first time-out event, the 32-bit watchdog counter is reloaded with the value of
the
Watchdog Timer Load (WDTLOAD)
register and resumes counting down from that value. If
the timer counts down to zero again before the first time-out interrupt is cleared, and watchdog reset
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System Control