68HC705JB4 datasheet(36/134 Pages) FREESCALE

36 / 134 page

GENERAL RELEASE SPECIFICATION

February 24, 1999

MOTOROLA

INTERRUPTS

MC68HC05JB4

4-6

REV 2

Figure 4-4. External Interrupt (IRQ2) Logic

4.5.3 IRQ Control/Status Register (ICSR) - $0A

The IRQ interrupt function is controlled by the ICSR located at $000A. All unused

bits in the ICSR will read as logic zeros. The IRQF bit is cleared and IRQE bit is

set by reset.

IRQR — IRQ Interrupt Acknowledge

The IRQR acknowledge bit clears an IRQ interrupt by clearing the IRQ latch.

The IRQR acknowledge bit will always read as a logic zero.

1 =

Writing a logic one to the IRQR acknowledge bit will clear the IRQ

latch.

0 =

Writing a logic zero to the IRQR acknowledge bit will have no effect

on the IRQ latch.

IRQF — IRQ Interrupt Request Flag

Writing to the IRQF ﬂag bit will have no effect on it. If the additional setting of

IRQF ﬂag bit is not cleared in the IRQ service routine and the IRQE enable bit

remains set the CPU will re-enter the IRQ interrupt sequence continuously until

either the IRQF ﬂag bit or the IRQE enable bit is clear. The IRQF latch is

cleared by reset.

1 =

Indicates that an IRQ request is pending.

0 =

Indicates that no IRQ request triggered by pins PA0-3 or IRQ is

pending. The IRQF ﬂag bit can be cleared by writing a logic one to

the IRQR acknowledge bit to clear the IRQ latch and also

conditioning the external IRQ sources to be inactive (if the level

sensitive interrupts are enabled via mask option). Doing so before

exiting the service routine will mask out additional occurrences of

the IRQF.

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

ICSR

IRQE

IRQ2E

IRQF

IRQ2F

$000A

IRQR

IRQ2R

reset:

10000000

Figure 4-5. IRQ Control and Status Register (ICSR)

IRQ2

LATCH

VDD

IRQ2

INTERRUPT

IRQ2E

IRQ2R

ICSR ($0A)

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

68HC705JB4 Datasheet(PDF) 36 Page - Freescale Semiconductor, Inc

68HC705JB4 Datasheet(HTML) 36 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL