Datasheet

5 System Control
System control determines the overall operation of the device. It provides information about the
device, controls the clocking to the core and individual peripherals, and handles reset detection and
reporting.
5.1 Signal Description
Table 5-1 on page 175 and Table 5-2 on page 175 list the external signals of the System Control
module and describe the function of each. The NMI signal is the alternate function for and functions
as a GPIO after reset. 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 297. The column in the table below titled "Pin Assignment" lists the GPIO pin
placement for the NMI signal. The AFSEL bit in the GPIO Alternate Function Select (GPIOAFSEL)
register (page 311) should be set to choose the NMI function. For more information on configuring
GPIOs, see “General-Purpose Input/Outputs (GPIOs)” on page 289. The remaining signals (with the
word "fixed" in the Pin Assignment column) have a fixed pin assignment and function.
Table 5-1. System Control & Clocks Signals (100LQFP)
DescriptionBuffer Type
a
Pin TypePin NumberPin Name
CPU Mode bit 0. Input must be set to logic 0 (grounded); other
encodings reserved.
TTLI65CMOD0
CPU Mode bit 1. Input must be set to logic 0 (grounded); other
encodings reserved.
TTLI76CMOD1
Main oscillator crystal input or an external clock reference
input.
AnalogI48OSC0
Main oscillator crystal output. Leave unconnected when using
a single-ended clock source.
AnalogO49OSC1
System reset input.TTLI64RST
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
Table 5-2. System Control & Clocks Signals (108BGA)
DescriptionBuffer Type
a
Pin TypePin NumberPin Name
CPU Mode bit 0. Input must be set to logic 0 (grounded); other
encodings reserved.
TTLIE11CMOD0
CPU Mode bit 1. Input must be set to logic 0 (grounded); other
encodings reserved.
TTLIB10CMOD1
Main oscillator crystal input or an external clock reference
input.
AnalogIL11OSC0
Main oscillator crystal output. Leave unconnected when using
a single-ended clock source.
AnalogOM11OSC1
System reset input.TTLIH11RST
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 176)
175June 18, 2012
Texas Instruments-Production Data
Stellaris
®
LM3S8962 Microcontroller
NRND: Not recommended for new designs.