STLC5466 datasheet(25/130 Pages) STMICROELECTRONICS

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STLC5466

III.10 - Interrupt Controller

III.10.1 - Description

Three external pins are used to manage the inter-

rupts generated by the Multi-HDLC. The interrupts

have three main sources:

– The operating interrupts generated by the HDLC

receivers/transmitters, the CI receivers and the

monitor transmitters/receivers. INT0 Pin is re-

served for this use.

– The interrupt generated by an abnormal working

of the clock distribution. INT1 Pin is reserved for

this use.

– The non-activity of the microprocessor (Watch-

dog). WDO Pin is reserved for this use.

III.10.2 - Operating Interrupts (INT0 Pin)

There are five main sources of operating interrupts

in the Multi-HDLC circuit:

– The HDLC receiver,

– The HDLC transmitter,

– The CI receiver,

– The Monitor receiver,

– The Monitor transmitter.

When an interrupt is generated by one of these

functions, the interrupt controller:

– Collects all the information about the reasons of

this interrupt

– Stores them in external memory.

– Informs the microprocessor by positioning the

INT0 pin in the high level.

Three interrupt queues are built in external mem-

ory to store the information about the interrupts:

– A single queue for the HDLC receivers and

transmitter

– One for the CI receivers

– One for the monitor receiver

The microprocessor takes the interrupts into ac-

count by reading the Interrupt Register (IR) of the

interrupt controller.

This register informs the microprocessor of the in-

terrupt source. The microprocessor will have infor-

mation about the interrupt source by reading the

corresponding interrupt queue (see Paragraph “In-

terrupt Register IR(38)H” on Page 74).

On an overflow of the circular interrupt queues and

an overrun or underrun of the different FIFO, the

INT0Pin is activated and the origin of the interrupt

is stored in the Interrupt Register.

A 16 bits register is associated with the Tx Monitor

interrupt. It informs the microprocessor of which

transmitter has generated the interrupt (see Para-

graph

“Transmit

Monitor

Interrupt

TMIR(30)H” on Page 71).

III.10.3 - Time Base Interrupts (INT1 Pin)

The Time base interrupt is generated when an ab-

sence or an abnormal working of clock distribution

is detected. The INT1 Pin is activated.

III.10.4 - Emergency Interrupts (WDO Pin)

The WDO signal is activated by an overflow of the

watchdog register.

III.10.5 - Interrupt Queues

There are three different interrupt queues:

– Tx and Rx HDLC interrupt queue

– Rx C/I interrupt queue

– Rx Monitor interrupt queue.

Their length can be defined by software.

For debugging function, each interrupt word of the

CI interrupt queue and monitor interrupt queue

can be followed by a time stamped word. It is com-

posed of a counter which runs in the range of

250

µs. The counter is the same as the watchdog

counter. Consequently, the watchdog function

isn’t available at the same time.

III.11 - Watchdog

This function is used to control the activity of the

application. It is composed of a counter which

counts down from an initial value loaded in the

Timer register by the microprocessor.

If the microprocessor doesn’t reset this counter

before it is totally decremented, the external Pin

WDO is activated; this signal can be used to reset

the microprocessor and all the application.

The initial time value of the counter is programma-

ble from 0 to 15s in increments of 0.25ms.

At the reset of the component, the counter is auto-

matically initialized by the value corresponding to

512ms which are indicated in the Timer register.

The microprocessor must put WDR (IDCR Regis-

ter) to”1” to reset this counter and to confirm that

the application started correctly.

In the reverse case, the WDO signal could be used

to reset the board a second time.

III.12 - Reset

There are two possibilities to reset the circuit:

–by software,

– by hardware.

Each programmable register receives its default

value. After that, the default value of each data

for Time slot Assigner memory.

STLC5466 Datasheet(PDF) 25 Page - STMicroelectronics

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