TM4C1231D5PZ Datasheet, PDF (200/1161 Pages) Texas Instruments – Universal Asynchronous Receiver/Transmitter Run Mode Clock

System Control
5 System Control
System control configures the overall operation of the device and provides information about the
device. Configurable features include reset control, NMI operation, power control, clock control, and
low-power modes.
5.1 Signal Description
The following table lists the external signals of the System Control module and describes the function
of each. The NMI signal is the alternate function for two GPIO signals and functions as a GPIO after
reset. PD7 and PF0 are under commit protection and require a special process to be configured as
any alternate function or to subsequently return to the GPIO function, see “Commit
Control” on page 624. The column in the table below titled "Pin Mux/Pin Assignment" lists the GPIO
pin placement for the NMI signal. The AFSEL bit in the GPIO Alternate Function Select
(GPIOAFSEL) register (page 639) should be set to choose the NMI function. The number in
parentheses is the encoding that must be programmed into the PMCn field in the GPIO Port Control
(GPIOPCTL) register (page 657) to assign the NMI signal to the specified GPIO port pin. For more
information on configuring GPIOs, see “General-Purpose Input/Outputs (GPIOs)” on page 616. The
remaining signals (with the word "fixed" in the Pin Mux/Pin Assignment column) have a fixed pin
assignment and function.
Table 5-1. System Control & Clocks Signals (100LQFP)
Pin Name
Pin Number Pin Mux / Pin Pin Type Buffer Type^a Description
Assignment
NMI
40
PF0 (8)
I
TTL
Non-maskable interrupt.
100
PD7 (8)
OSC0
65
fixed
I
Analog Main oscillator crystal input or an external clock
reference input.
OSC1
66
fixed
O
Analog Main oscillator crystal output. Leave unconnected
when using a single-ended clock source.
RST
63
fixed
I
TTL
System reset input.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
5.2 Functional Description
The System Control module provides the following capabilities:
■ Device identification, see “Device Identification” on page 200
■ Local control, such as reset (see “Reset Control” on page 201), power (see “Power
Control” on page 206) and clock control (see “Clock Control” on page 207)
5.2.1
■ System control (Run, Sleep, and Deep-Sleep modes), see “System Control” on page 213
Device Identification
Several read-only registers provide software with information on the microcontroller, such as version,
part number, memory sizes, and peripherals present on the device. The Device Identification 0
(DID0) (page 224) and Device Identification 1 (DID1) (page 226) registers provide details about the
device's version, package, temperature range, and so on. The Peripheral Present registers starting
at System Control offset 0x300, such as the Watchdog Timer Peripheral Present (PPWD) register,
provide information on how many of each type of module are included on the device. Finally,
200
July 16, 2013
Texas Instruments-Production Data