MC68HC908AP16CFB datasheet(208/440 Pages) MOTOROLA

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Timebase Module (TBM)

Data Sheet

MC68HC908AP Family — Rev. 2.5

208

MOTOROLA

NOTE:

Do not change TBR[2:0] bits while the timebase is enabled

(TBON = 1).

TACK — Timebase ACKnowledge

The TACK bit is a write-only bit and always reads as 0. Writing a logic

1 to this bit clears TBIF, the timebase interrupt flag bit. Writing a logic

0 to this bit has no effect.

1 = Clear timebase interrupt flag

0 = No effect

TBIE — Timebase Interrupt Enabled

This read/write bit enables the timebase interrupt when the TBIF bit

becomes set. Reset clears the TBIE bit.

1 = Timebase interrupt enabled

0 = Timebase interrupt disabled

TBON — Timebase Enabled

This read/write bit enables the timebase. Timebase may be turned off

to reduce power consumption when its function is not necessary. The

counter can be initialized by clearing and then setting this bit. Reset

clears the TBON bit.

1 = Timebase enabled

0 = Timebase disabled and the counter initialized to 0’s

12.5 Interrupts

The timebase module can interrupt the CPU on a regular basis with a

rate defined by TBR[2:0]. When the timebase counter chain rolls over,

the TBIF flag is set. If the TBIE bit is set, enabling the timebase interrupt,

the counter chain overflow will generate a CPU interrupt request. The

interrupt vector is defined in Table 2-1 . Vector Addresses.

Interrupts must be acknowledged by writing a logic 1 to the TACK bit.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

MC68HC908AP16CFB Datasheet(PDF) 208 Page - Motorola, Inc