M68ICS08GR datasheet(330/408 Pages) FREESCALE

No. de pieza	M68ICS08GR

Descripción Electrónicos	M68HC08 Microcontrollers

PDF	408 Pages

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Fabricante Electrónico	FREESCALE [Freescale Semiconductor, Inc]

Página de inicio	http://www.freescale.com

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330 / 408 page

Timebase Module (TBM)

Technical Data

MC68HC908GR8 — Rev 4.0

330

Timebase Module (TBM)

MOTOROLA

21.4 Functional Description

NOTE:

This module is designed for a 32.768 kHz oscillator.

This module can generate a periodic interrupt by dividing the crystal

frequency, CGMXCLK. The counter is initialized to all 0s when TBON bit

is cleared. The counter, shown in Figure 21-1, starts counting when the

TBON bit is set. When the counter overflows at the tap selected by

TBR2:TBR0, the TBIF bit gets set. If the TBIE bit is set, an interrupt

request is sent to the CPU. The TBIF flag is cleared by writing a 1 to the

TACK bit. The first time the TBIF flag is set after enabling the timebase

module, the interrupt is generated at approximately half of the overflow

period. Subsequent events occur at the exact period.

Figure 21-1. Timebase Block Diagram

÷2

CGMXCLK

0 0 0

0 0 1

0 1 0

0 1 1

TBIF

TBIE

TBMINT

TBON

÷2

1 0 0

1 0 1

1 1 0

1 1 1

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M68ICS08GR Datasheet(PDF) 330 Page - Freescale Semiconductor, Inc