LM3S1G21 Datasheet, PDF(400/955 Page) Texas Instruments – Stellaris® LM3S1G21 Microcontroller

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LM3S1G21 Datasheet, PDF (400/955 Pages) Texas Instruments – Stellaris® LM3S1G21 Microcontroller

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General-Purpose Input/Outputs (GPIOs)

signals are 5-V tolerant and are connected directly to their circuitry (C0-, C0+, C1-, C1+). These

signals are configured by clearing the DEN bit in the GPIO Digital Enable (GPIODEN) register. All

GPIO signals are 5-V tolerant when configured as inputs except for PB0 and PB1, which are limited

to 3.6 V. The digital alternate hardware functions are enabled by setting the appropriate bit in the

GPIO Alternate Function Select (GPIOAFSEL) and GPIODEN registers and configuring the PMCx

bit field in the GPIO Port Control (GPIOPCTL) register to the numeric encoding shown in the table

below. Note that each pin must be programmed individually; no type of grouping is implied by the

columns in the table. Table entries that are shaded gray are the default values for the corresponding

GPIO pin.

Important: All GPIO pins are configured as GPIOs and tri-stated by default (GPIOAFSEL=0,

GPIODEN=0, GPIOPDR=0, GPIOPUR=0, and GPIOPCTL=0, with the exception of the

pins shown in the table below. A Power-On-Reset (POR) or asserting RST puts the pins

back to their default state.

Table 9-1. GPIO Pins With Non-Zero Reset Values

GPIO Pins

PA[1:0]

PA[5:2]

PB[3:2]

PC[3:0]

Default State

UART0

SSI0

I2C0

JTAG/SWD

GPIOAFSEL GPIODEN GPIOPDR GPIOPUR

0

0

0

0

0

0

0

0

0

0

0

0

1

1

0

1

GPIOPCTL

0x1

0x2

0x3

0x1

Table 9-2. GPIO Pins and Alternate Functions (100LQFP)

IO

Pin

Analog

Function

1

2

Digital Function (GPIOPCTL PMCx Bit Field Encoding)a

3

4

5

6

7

8

9

10

11

PA0 26

-

U0Rx

-

-

-

-

-

- I2C1SCL U1Rx

-

-

PA1 27

-

U0Tx

-

-

-

-

-

- I2C1SDA U1Tx

-

-

PA2 28

- SSI0Clk -

-

-

-

-

-

-

-

-

-

PA3 29

- SSI0Fss -

-

-

-

-

-

-

-

-

-

PA4 30

- SSI0Rx -

-

-

-

-

-

-

-

-

-

PA5 31

- SSI0Tx -

-

-

-

-

-

-

-

-

-

PA6 34

- I2C1SCL CCP1

-

-

-

-

-

-

U1CTS

-

-

PA7 35

- I2C1SDA CCP4

-

-

-

-

CCP3

-

U1DCD

-

-

PB0 66

-

CCP0

-

-

-

U1Rx

-

-

-

-

-

-

PB1 67

-

CCP2

-

-

CCP1 U1Tx

-

-

-

-

-

-

PB2 72

- I2C0SCL -

-

CCP3 CCP0

-

-

-

-

-

-

PB3 65

- I2C0SDA -

-

-

-

-

-

-

-

-

-

PB4 92 C0-

-

-

-

U2Rx

-

-

U1Rx EPI0S23 -

-

-

PB5 91 C1-

C0o CCP5 CCP6 CCP0

-

CCP2 U1Tx EPI0S22 -

-

-

PB6 90 VREFA CCP1 CCP7 C0o

-

-

CCP5

-

-

-

-

-

C0+

PB7 89

-

-

-

-

NMI

-

-

-

-

-

-

-

PC0 80

-

-

-

TCK

-

-

-

-

-

-

-

-

SWCLK

PC1 79

-

-

-

TMS

-

-

-

-

-

-

-

-

SWDIO

400

January 22, 2012

Texas Instruments-Production Data

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