HC705JB2GRSSLASHH datasheet(57/128 Pages) NXP

57 / 128 page

August 28, 1998

GENERAL RELEASE SPECIFICATION

MULTI-FUNCTION TIMER

REV 1.1

8-3

8.1.2 Timer Control/Status Register (TCSR) $08

The TCSR contains the timer interrupt ﬂag bits, the timer interrupt enable bits, and

the real time interrupt rate select bits. Bit 2 and bit 3 are write-only bits which will

read as logical zeros. Figure 8-3 shows the value of each bit in the TCSR

following reset.

Figure 8-3. Timer Control/Status Register (TCSR)

TOF - Timer Overﬂow Flag

The TOF is a read-only ﬂag bit.

1 =

Set when the 8-bit ripple counter rolls over from $FF to $00. A

TIMER Interrupt request will be generated if TOFE is also set.

0 =

Reset by writing a logical one to the TOF acknowledge bit, TOFR.

Writing to the TOF ﬂag bit has no effect on its value. This bit is

cleared by reset.

RTIF - Real Time Interrupt Flag

The RTIF is a read-only ﬂag bit.

1 =

Set when the output of the chosen (1 of 4 selections) Real Time

Interrupt stage goes active. A TIMER Interrupt request will be

generated if RTIE is also set.

0 =

Reset by writing a logical one to the RTIF acknowledge bit, RTIFR.

Writing to the RTIF ﬂag bit has no effect on its value. This bit is

cleared by reset.

TOFE - Timer Overﬂow Enable

The TOFE is an enable bit that allows generation of a TIMER Interrupt upon

overﬂow of the Timer Counter Register.

1 =

When set, the TIMER Interrupt is generated when the TOF ﬂag bit is

set.

0 =

When cleared, no TIMER interrupt caused by TOF bit set will be

generated. This bit is cleared by reset.

RTIE - Real Time Interrupt Enable

The RTIE is an enable bit that allows generation of a TIMER Interrupt by the

RTIF bit.

1 =

When set, the TIMER Interrupt is generated when the RTIF ﬂag bit is

set.

0 =

When cleared, no TIMER interrupt caused by RTIF bit set will be

generated. This bit is cleared by reset.

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

TCSR

TOF

RTIF

TOFE

RTIE

RT1

RT0

$0008

TOFR

RTIFR

reset:

00000011

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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