EM78451AP datasheet(34/54 Pages) EMC

34 / 54 page

EM78451

8-Bit Microcontroller

•

Product Specification (V1.2) 05.27.2004

(This specification is subject to change without further notice)

BC 0x0C,1

NOP

JMP SPI

DELAY:

; (User’s program)

EOP

ORG 0XFFF

JMP INITI

4.6 Timer 1

4.6.1

Overview

Timer1(TMR1) is an eight-bit clock counter with a programmable prescaler. It is

designed for the SPI module as a baud rate clock generator. TMR1 can be read,

written, and cleared on any reset conditions. If employed, it can be turned down for

power saving by setting TMR1EN bit [T1CON<2>] to 0.

4.6.2

Function description

Fig. 15 shows TIMER1 block diagram. Each signal and block is described as follows:

Fig. 15 TIMER1 Block Diagram

OSC/4:Input clock.

Prescaler: Option of 1:1, 1:4, 1:8, and 1:16 defined by T1P1 and T1P02(T1CON<1,

0>). It is cleared when a value is written to TMR1 or T1CON, and during any kind of

reset as well.

PWP: Pulse width preset register; the desired width of baud clock is written in

advance.

TMR1: Timer 1 register; TMR1 increases until it matches with PWP, and then

resets to 0. If it is chosen optionally in the SPI mode, its output is fed as a shifting

clock.

EM78451AP Datasheet(PDF) 34 Page - ELAN Microelectronics Corp