LM3S9B81 Datasheet, PDF (97/1155 Pages) Texas Instruments – Stellaris® LM3S9B81 Microcontroller

Stellaris® LM3S9B81 Microcontroller
6 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.
6.1 Signal Description
Table 6-1 on page 97 and Table 6-2 on page 97 list the external signals of the System Control
module and describe the function of each. The NMI signal is the alternate function for the GPIO PB7
signal and functions as a GPIO after reset. PB7 is under commit protection and requires a special
process to be configured as the NMI signal or to subsequently return to the GPIO function, see
“Commit Control” on page 302. 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 318) 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 336) 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 294. The
remaining signals (with the word "fixed" in the Pin Mux/Pin Assignment column) have a fixed pin
assignment and function.
Table 6-1. Signals for System Control & Clocks (100LQFP)
Pin Name
Pin Number Pin Mux / Pin Pin Type Buffer Type^a Description
Assignment
NMI
89
PB7 (4)
I
TTL
Non-maskable interrupt.
OSC0
48
fixed
I
Analog Main oscillator crystal input or an external clock
reference input.
OSC1
49
fixed
O
Analog Main oscillator crystal output. Leave unconnected
when using a single-ended clock source.
RST
64
fixed
I
TTL
System reset input.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
Table 6-2. Signals for System Control & Clocks (108BGA)
Pin Name
Pin Number Pin Mux / Pin Pin Type Buffer Type^a Description
Assignment
NMI
A8
PB7 (4)
I
TTL
Non-maskable interrupt.
OSC0
L11
fixed
I
Analog Main oscillator crystal input or an external clock
reference input.
OSC1
M11
fixed
O
Analog Main oscillator crystal output. Leave unconnected
when using a single-ended clock source.
RST
H11
fixed
I
TTL
System reset input.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
6.2 Functional Description
The System Control module provides the following capabilities:
■ Device identification, see “Device Identification” on page 98
June 29, 2010
97
Texas Instruments-Advance Information