HT9480 datasheet(25/47 Pages) HOLTEK

25 / 47 page

HT9480

Rev. 1.20

July 31, 2002

Error indication

After error correction, any code-word containing more

than two bits random error or four bits burst error (op-

tion) in address or message code-word may be indi-

cated from the error flag position.

Data transfer

Data transfer is initiated once the code-word is already

received. When the HT9480 is ready to transfer the re-

ceived call data, an external interrupt will be generated

via output INT. Any message data can be read by ac-

cessing the 1FH address of the MCU RAM map via the

MCU internal bus.

The address word indicates call address, function 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 ter-

mination word is transferred.

Address word format

Bit 7

Bit 6 Bit 5 Bit 4

Bit 3

Bit 2 Bit 1 Bit 0

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 termination and

address word format

Bit 3=1 if a duplicate code-word.

Bit 6

Bit 5

Bit 4

Call Address

000

001

010

011

100

101

110

111

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 internal data ready inter-

rupt and battery fail interrupt share the same pin con-

nection. Checking the battery fail interrupt bit (BF; bit 4

of 1EH) and the data ready interrupt bit (DR;bit7of1

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 inter-

val defined by SPF06, SPF07 does not receive any pre-

amble or sync code word. This signal will be used as

²loss of RF signal² indicator.

Duplicate call suppression

The HT9480 provides a Duplicate Call Suppression with

time-out facility, to identify duplicate call reception. In

display pager mode, duplicate call indication is achieved

only via the MCU interface. A call is assumed to be du-

plicate if its address and function bit setting is equal to

the latest received call, which initialized the call address

and function bit reference. The Duplicate Call suppres-

sion time-out is selected by programming SPF06,

SPF07.

Configuration RAM organization

The decoder contains a 21-byte RAM to store 6 user ad-

dresses, 6 independently programmable frame num-

bers and specially programmed function bits

(SPF00~SPF23) for the decoder application configura-

tion. The data memory is mapped to the addresses

40H~54H of bank 27.

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