SNC21085

1-CH H.Q. Speech Controller

5.6

I/O Ports

There are three 4-bit I/O ports P1, P2 and P3. Any I/O can be individually

programmed as either input pull low or output. Any valid data transition (H

L or

L

H) of P1, P2 and P3 can reactivate the chip when it is in power-down stage.

I/O Port Configuration

Note:

Port Data

Port Status

To Internal Data Bus

Read Control

PAD

Weak

(1) Weak N-MOS can serve as pull-low resistor.

(2) The driving/sink current of P3.3 & P3.2 is up to 8mA/16mA

5.7

IR Function

Bit 3 of Mode Register is applied to control the IR function. P33 can be modulated with

controlled by Mode1.1. If Mode1.1 set 1 IR is use P2.3, set “0” is use P3.3. The IR

signal can be achieved by this modulated signal.

5.8

PWM IO control

SNC21085 have support 4 PWM IO (P30~P33). Each I/O has 8 bits independent duty

register.

5.9

Watch Dog Timer

SNC21085 built an internal WDT (Watch Dog Timer). This Watchdog timer would

issue resets signal to this chip if it is not cleared before reaching terminal count (1sec).

The watchdog timer is enabled at reset and cannot be disabled.

Ver: 1.0

November 08, 2006

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