VII LCD CONTROLLER BLOCK: LCD CONTROLLER

Controlling the GPIO Pins

The pins described below can be used as general-purpose output (GPO) pins or general-purpose input/output (GPIO) pins, through panel selection or other settings.

General-purpose output (GPO) pins

The FPDAT[3:0] signal output pins can be used as general-purpose output GPO[6:3] pins when a 4-bit LCD panel (LDDW[1:0] (D[1:0])/0x39FFE1) = "00") is used. The GPO output control bits are listed in Table 2.19.

Table 2.19 GOP Control Bits

Pin name

GPO signal name

Output control bit

FPDAT0

GPO3

GPO3D (D3)/GPIO status/control register(0x39FFF9)

FPDAT1

GPO4

GPO4D (D4)/GPIO status/control register(0x39FFF9)

FPDAT2

GPO5

GPO5D (D5)/GPIO status/control register(0x39FFF9)

FPDAT3

GPO6

GPO6D (D6)/GPIO status/control register(0x39FFF9)

Setting the GPOxD bit to 1 drives the GPOx output high, and setting the GPOxD bit to 0 drives the GPOx output low.

Note: In power-save or doze mode, these pins are fixed low.

General-purpose input/output (GPIO) pins

While the LCD controller is enabled (LCDCEN (D5)/LCDC mode register 2 = "1"), bus release requests (#BUSREQ) from outside the chip can be disabled. When the BREQEN (D2)/LCDC system control register (0x39FFFD) is set to "0" (default), bus release requests from outside will no longer be accepted while LCDCEN = "1". As a result, the pins listed below will not be used for bus-release purposes, and can therefore be used as general-purpose input/output (GPIO) pins. Because these pins are usable only while the LCD controller remains enabled, the control registers in the LCD controller block must be used to control their direction for input or output, as well as to read/write data to and from them.

Table 2.20 GPIO Control Bits

Pin name

GPIO signal

I/O control bit

I/O data

name

 

 

 

#BUSREQ/P34

GPIO0

GPIO0C (D0)/GPIO configuration

GPIO0D (D0)/GPIO status/control

 

 

register(0x39FFF8)

register(0x39FFF9)

#BUSACK/P35

GPIO1

GPIO1C (D1)/GPIO configuration

GPIO1D (D1)/GPIO status/control

 

 

register(0x39FFF8)

register(0x39FFF9)

#BUSGET/P31

GPIO2

GPIO2C (D2)/GPIO configuration

GPIO2D (D2)/GPIO status/control

 

 

register(0x39FFF8)

register(0x39FFF9)

Set the GPIOxC bits to "0" (default) when the GPIOx pins are used as input ports, or "1" when the GPIOx pins are used as output ports.

When the pins are set for input, it possible to determine their input-voltage level by reading GPIOxD. The value "1" is indicated when the input voltage is high, and "0" indicated when the input voltage is low. When the pins are set for output, write output data to GPIOxD. Setting the GPIOxD bit to "1" drives the GPIOx output high, and setting the GPIOxD bit to "0" drives the GPIOx output low.

B-VII-2-30

EPSON

S1C33L03 FUNCTION PART