HT9480 datasheet(31/57 Pages) HOLTEK

31 / 57 page

Error indication

After error correction, any code-word contain-

ing more than two bits random error or four bits

burst error (option) in address or message code-

word may be indicated from the error flag posi-

tion.

Data transfer

Data transfer is initiated once the code-word is

already received. When the HT9480 is ready to

transfer the received call data, an external in-

terrupt will be generated via output INT. Any

message data can be read by accessing the 1FH

address of the

µC RAM map via the µC internal

bus.

The address word indicates call address, func-

tion bit setting, and decoder flags. The message

code-words are received and concatenated to a

valid call address word. The message words

derived from un-corrected message code-words.

Data transfer for a received call ends right after

the termination word is transferred.

Address word format

Bit

Sync.

State

Call

address

Dup.

Call

Function

code

Bit 0: Bit 21 of the address code-word

Bit 1: Bit 20 of the address code-word

Bit 2=0 is to tell the difference between termi-

nation and address word format

Bit 3=1 if a duplicate code-word.

Bit 6

Bit 5

Bit 4

Call Address

RIC A

RIC B

RIC C

RIC D

RIC E

RIC F

—

Bit 7= 1 if an address code-word is received in

the data fail mode.

Interrupt indication

The HT9480 provides an internal data ready

interrupt and a battery fail interrupt. The in-

ternal data ready interrupt and battery fail

interrupt share the same pin connection.

Checking the battery fail interrupt bit (BF; bit

4 of 1EH) and the data ready interrupt bit (DR;

bit 7 of 1 EH) will tell which type of interrupt

has

occurred. Both interrupt bits are active

low.

Out-of-range indication

The out-of-range condition occurs when the

time interval defined by SPF06, SPF07 does not

receive any preamble or sync code word. This

signal will be used as “loss of RF signal” indica-

tor.

HT9480

23th Feb ’98

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