Texas Instruments Stellaris IDM-L35, Руководство пользователя

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Stellaris® Intelligent Display Module with 3.5" Display
August 7, 2009 15
The LCD panel incorporates a white LED backlight with 6 LEDs in series which requires a high
power serial driver (U7) for operation. The backlight power driver shutdown input is controlled by
microcontroller GPIO pin PH0/CCP6. For full brightness, set PH0 high. For dim control, a 1 kHz
PWM signal can be generated with CCP6.
For additional LCD panel information, refer to the data sheet on the RDK-IDM-L35 CD and LCD
driver source code in the Stellaris graphics library.
Touch Panel
Four ADC channels and four GPIO lines connect directly to the resistive touch panel, allowing the
microcontroller to manage all aspects of operation.
X and Y axis position measurements are made independently.
For X-axis measurement, GPIO pins PC4 and PC5 are set HIGH and LOW respectively to form a
resistor divider between 3 V and 0 V. The voltage on ADC4 and ADC5 indicates the X-axis
position.
To measure the Y-axis position, PD2 and PD3 are set HIGH and LOW respectively and the voltage
on ADC6 or ADC7 is measured.
Software controls calibration and finger press detection functions.
High Power LED Driver
The LCD panel backlight has 6 LEDs in series and requires a high power LED driver (U7) for
operation, providing 20 mA at 20 V. The LCD_BL signal driven from a microcontroller GPIO is
used to turn the backlight on and off. A 1 kHZ PWM signal can be used instead for dim control.
3.3 V DC Regulator
The IDM-L35 operates with 5 V DC, which can be applied via DC jack J7, terminal block J1, or
header J8. The RDK includes a USB to TTL serial cable that connects to J8 and receives 5 V from
the USB port. DC regulator U3 generates 3.3 V for powering the board circuits and includes power
indicator LED D1.
UART, microSD Card Slot, Speaker, Analog Inputs, Digital I/O (Schematic
page 3)
The third schematic page contains the UART RS-232 transceiver, microSD card slot, speaker,
terminal blocks, and headers.
RS232 Serial Port
The MAX3221 (U2) line transceiver interfaces between UART2 and the RS232 port pins on J3.
UART2 uses ports PG0 and PG1.
microSD Card Slot
Standard microSD media may be used for image or data storage. The SD card is wired for use in
SPI mode, rather than the 1-bit or 4-bit SD modes.
Speaker
Speaker SPK1 is a small magnetic audio transducer which is driven by PC7/CCP4 through a small
transistor. CCP4 can be configured to generate a free-running tone at the required frequency.