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, which default to GPIO after
reset. The
NMI
pins 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 752 for more information. The column in the table below titled "Pin Mux/Pin
Assignment" lists the GPIO pin placement for the
NMI
signal. The number in parentheses next to
the pin placement listed is the encoding that must be programmed into the
PMCn
field in the
GPIO
Port Control (GPIOPCTL)
register (page 787) to assign the
NMI
signal to the specified GPIO port
pin. In addition, the
AFSEL
bit in the
GPIO Alternate Function Select (GPIOAFSEL)
register
(page 770) should be set to choose the NMI function. For more information on configuring GPIOs,
see “General-Purpose Input/Outputs (GPIOs)” on page 742. The remaining signals listed in the table
(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 (128TQFP)
Description
Buffer Type
Pin Type
Pin Mux / Pin
Assignment
Pin Number
Pin Name
An optionally divided reference clock output based
on a selected clock source. Note that this signal is
not synchronized to the System Clock.
TTL
O
PQ4 (7)
102
DIVSCLK
Non-maskable interrupt.
TTL
I
PD7 (8)
128
NMI
Main oscillator crystal input or an external clock
reference input.
Analog
I
fixed
88
OSC0
Main oscillator crystal output. Leave unconnected
when using a single-ended clock source.
Analog
O
fixed
89
OSC1
System reset input.
TTL
I
fixed
70
RST
5.2
Functional Description
The System Control module provides the following capabilities:
■ Device identification, see “Device Identification” on page 220
■ Configurable control of reset, power, and clock sources.
■ System control (Run, Sleep, and Deep-Sleep modes), see “System Control” on page 239
5.2.1
Device Identification
Read-only registers in the system control module provide information about the microcontroller,
such as version, part number, pin count, operating temperature range and available peripherals on
the device. The
Device Identification 0 (DID0)
(page 255) and
Device Identification 1 (DID1)
(page 257) 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
June 18, 2014
220
Texas Instruments-Production Data
System Control
