XRT79L71IB datasheet(81/109 Pages) EXAR

81 / 109 page

XRT79L71

REV. 1.0.0

1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC - HARDWARE

These Operation Block Interrupt Enable registers permit the user to individually enable or disable the interrupt

requesting capability of the functional blocks within the XRT79L71. If a particular bit-field, within this register

contains the value "0", then the corresponding functional block has been disabled for generating any interrupt

requests. Conversely, if that bit-field contains the value "1", then the corresponding functional block has been

enabled for interrupt generation (e.g., those potential interrupts, within the enabled functional block that are

enabled at the source level are now enabled). The user should be aware of the fact that each functional block,

within the XRT79L71 contains multiple potential interrupt sources. Each of these lower lever interrupt sources

contain their own set of interrupt enable bits and interrupt status bits, existing in various on-chip registers.

STEP 2 - Interrupt Service Routing Branching: After reading the Operation Block Interrupt Status

Registers

The contents of the Operation Block Interrupt Status Registers permit the user to identify which of the seven (7)

functional blocks (within the XRT79L71 IC) have requested interrupt service. The µC/µP should use this

information in order to determine where, within the Interrupt Service Routine, program control should branch

to. The following table can be viewed as an interrupt service routine guide. It lists each of the Functional

Blocks that contain bit-fields in the Operation Block Interrupt Status and Enable registers. Additionally, this

table also presents a list and addresses of the corresponding on-chip Registers that the Interrupt Service

Routine should branch to and read, based upon the Interrupting Functional Block.

Operation Interrupt Enable Register - Byte 1 (Address = 0x0116)

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

Unused

DS3/E3 LIU/

JA Block

Interrupt

Enable

DS3/E3

Framer

Block Inter-

rupt Enable

Unused

R/O

R/W

R/O

Operation Interrupt Enable Register - Byte 0 (Address = 0x0117)

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

Unused

Receive

ATM Cell/

PPP Proces-

sor BlockIn-

terrupt

Enable

Unused

Transmit

ATM Cell/

PPP Proces-

sor Block

Interrupt

Enable

R/O

R/W

R/O

R/W

TABLE 5: INTERRUPT SERVICE ROUTINE GUIDE FOR THE XRT79L71

INTERRUPT FUNCTIONAL

BLOCK

THE NEXT REGISTER TO BE READ DURING THE INTERRUPT SERVICE ROUTINE

ADDRESS

LOCATION

DS3/E3 Framer Block

Framer Block Interrupt Status Register

0x1105

DS3/E3 LIU/JA Block

LIU Interrupt Status Register

0x1302

XRT79L71IB Datasheet(PDF) 81 Page - Exar Corporation

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