SNL310

16-Bit LCD Controller

4. I/O PORT

SNL310 provides totally 64 I/O pins (P2.0~P2.15, P3.0~P3.15, P4.0~P4.15, and

P5.0~P5.15). The input pull high resistor of each pin can be programmed by Port

Pull-High Register and the direction of I/O port is selected by Port Direction Register.

The Port2 (P2.0~P2.15) and Port3 (P3.0~P3.15) can wake the chip up from the stop

mode and watch mode.

These 64 programmable I/O pins provides not only a simply input/output function but

also flexible configuration. It can be configured to be an 8-bit microprocessor interface

to drive external devices, such as mask ROM, Flash and SRAM and LCD driver.

Furthermore, the pins “TxD” and “RxD” are shared with P3.0 and P3.1.

The internal structure of I/O pins is showed in Figure-2.

Pull-Up

Resister

Latch

PAD

to internal bus

Pull-Up

Select

In/Out

Control

In/Out

Control

I/O Configuration of Port2 ~ Port5

Figure-2

In some applications (e.g., Infra Red, IR), an output port needs to be modulated a carry

signal. In the cases, the routine of modulation will occupy too many CPU computations.

Thus, a modulation circuit is built in chip to reduce CPU’s loading,

Timer2

overflow

P3.3

2

IREN

I/O Pad

Figure-3

Ver: 1.7

May 2, 2003

5