Datasheet

WVGA/LCD EI3 Extender Board Manual 2-13
WVGA/LCD EI3 Extender Board Hardware Reference
LCD SPI Chip Select
The LCD SPICS switch connects the chip select pin of the serial peripheral
interconnect interface (SPI) of the LCD to one of three SPI select pins of
the processor. U10 ports GPE3, GPE4, and GPE5 select the connection to the
appropriate SPICS signal via the U31 bus switch.
PPICLK_DIR Select
The PPICLK_DIR select switch determines whether the LCD clock is gener-
ated by an on-board oscillator or by the processor. By driving the
PPICLK_DIR signal (U10 port GPE7) high, the on-board oscillator is enabled
and driven to the LCD and processor via the U1 dual-supply bus trans-
ceiver. By driving the PPICLK_DIR signal low, the on-board oscillator is
disabled, and the clock from the processor is driven to the LCD via the U1
dual-supply bus transceiver.
LCD Mode Select
The LCD mode select switch determines whether the interface to the pro-
cessor’s PPI is 16, 18, or 24 bits. In 16-bit mode, RGB565 is supported.
In 18-bit mode, RGB666 is supported. In 24-bit mode, RGB888 is sup-
ported. The LCD mode is selected by driving low the 24_BIT_LCD_MODE
(U10 port GPF5), 18_BIT_LCD_MODE (U10 port GPF6), or 16_BIT_LCD_MODE
(U10 port GPF7) signal. Driving one of these signals low enables the appro-
priate bus switch (U14–16).
AD7879 PENIRQ Signal
The AD7879 PENIRQ switch connects the interrupt signal of the AD7879
touch screen controller to one of eight GPIO pins of the processor. U10
ports GPA0–7 select the connection to the appropriate GPIO signal via the
U40 and U41 bus switches.