CHAPTER 1 INTRODUCTION
User’s Manual U14272EJ3V0UM
34
1.3.15 Programmable chip selects
The V
R
4181 provides support for 2 programmable chip selects (PCS) which are also available as general-purpose
I/O pins. Each PCS can decode either I/O or memory accesses and can optionally be qualified to read, write, or both
read and write.
1.3.16 LCD interface
The LCD controller of the V
R
4181 is Unified Memory Architecture (UMA) based in which the frame buffer is part of
system DRAM. The LCD controller supports monochrome STN LCD panels having 4-bit data bus interfaces and color
STN LCD panels having 8-bit data bus interface. When interfacing to a color LCD panel, general-purpose I/O pins
must be allocated to provide the upper nibble of the 8-bit LCD data bus.
In monochrome mode, the LCD controller supports 1-bpp mode (mono), 2-bpp mode (4 gray levels) and 4-bpp
mode (16 gray levels). In color mode, it supports 4-bpp mode (16 colors) and 8-bpp mode (256 colors).
The LCD controller includes a 256-entry x 18-bit color pallet. In 8-bpp color modes, the pallet is used to select 256
colors out of possible 262,144 colors.
The LCD controller supports LCD panels of up to 320 x 320 pixels. Typical LCD panel horizontal/vertical
resolutions are as follows.
Table 1-4. LCD Panel Resolutions (in Pixels, TYP.)
Horizontal resolution
Vertical resolution
320
320
320
240
320
160
240
320
240
240
240
160
160
320
160
240
160
160
The LCD controller also provides power-on and power-down sequence control for the LCD panel via the VPLCD
and VPBIAS pins. Power sequencing is provided to prevent latch-up damage to the panel.
The LCD controller can be disabled to allow connection of an external LCDC with integrated frame buffer RAM
such as NEC Electronics’
µ
PD16661. When the internal LCD controller is disabled, the SHCLK, LOCLK, VPLCD,
and VPBIAS pins are redefined as follows:
Table 1-5. Functions of LCD Interface Pins when LCD Controller Is Disabled
Redefined function
Default function
LCDCS#
SHCLK
MEMCS16#
LOCLK
VPGPIO1
VPLCD
VPGPIO0
VPBIAS