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Functional Description

2.1.11 Temperature Sensor

The ambient temperature is measured by the Texas Instruments TMP100 temperature sensor (U4), which

is connected to the TM4C129X by I2C.

I2C module 6 is used to interface with the temperature sensor, which has a maximum resolution of 12 bits.

The TMP100 is accurate to +/- 2 °C within the range of -25 to +85 °C.

The initial value of the I2C slave address is 0b1001010 or 0x4A, code required to configure them. If the

default address conflicts with another device you have added to the I2C bus, the address can be changed

by populating or unpopulating resistors R29, R30, R24 and/or R25. Refer to the "Serial Bus Address"

section of the TMP100 datasheet for the various address settings.

There are 2.2-kΩ pull-up resistors on the SDA and SCL lines as required by the I2C specification. Refer to

the following table for connections to I2C temperature sensor:

Port Function Jumper to shunt

PB6 I2C6 SCL J18

PB7 I2C6 SDA J20

2.1.12 LCD

The DK-TM4C129X is equipped with a Kentec K350QVG-V2-F 320x240 RGB resistive touch screen that

is controlled by the LCD Controller of the TM4C129X MCU using the LCD Interface Display Driver (LIDD)

in 8-bit mode.

The backlight of the LCD is driven by a TI TPS61042 constant current supply (U9). The control line of U9

has multiple settings that are set by moving the shunt on J35.

Shunt Across Effect

Pins 1 and 2 (default) Always on

Backlight control is handled by PF1

Pins 2 and 3

(This pin is also used as an Ethernet LED; remove the shunt on pin 5 and 6 for jumper J33)

None Always off

CAUTION

If the LCD is disconnected, remove the shunt, otherwise the U9 current

supply will get very hot and may be damaged.

The resistive touch screen works by reading one axis at a time. For example, to read the X-axis, set PE7

to high, PT2 to ground, and tri-state PT3. Then read the analog value of PP7. The higher the voltage, the

farther left the user is on the touch screen. To read the Y-axis, set PT3 to high, PP7 to ground, and tri-

state PT2. Then read the analog value of PE7. The higher the voltage, the higher the user is on the touch

screen. Refer to Figure 2-5.

SPMU360–October 2013 Hardware Description

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