FIFO

LOAD

CONTROL

SEL

EN

CONTROL

BIT

/

R/W

CONTROL

32 TO 16 DRIVER

32 BIT SHIFT REGISTER

TO PINS

CONTROLBITS

CR0, CR14

CLOCK

OPTION

CLOCK

CLK

BIT

COUNTER

AND

END OF

SEQUENCE

PARITY

CHECK

32ND

BIT

DATA

BIT CLOCK

WORD GAP

WORD GAP

TIMER

BIT CLOCK

END

START

SEQUENCE

CONTROL

ERROR

CLOCK

ERROR

DETECTION

SHIFT REGISTER

SHIFT REGISTER

NULL

ZEROS

SHIFT REGISTER

ONES

EOS

FIGURE 2.

RECEIVER BLOCK DIAGRAM

LABEL /

DECODE

COMPARE

16 x 8

LABEL

MEMORY

32 X 32

FIFO

D/R

FF

MUX

CONTROL

BITS

HF

FUNCTIONAL DESCRIPTION (cont.)

HI-8582, HI-8583

RECEIVER PARITY

The 32nd bit of received ARINC words stored in the receive FIFO

is used as a Parity Flag indicating whether good Odd parity is

received from the incoming ARINC word.

Odd Parity Received

The parity bit is reset to indicate correct parity was received

and the resulting word is written to the receive FIFO.

Even Parity Received

The receiver sets the 32nd bit to a “1”, indicating a parity error

and the resulting word is then written to the receive FIFO.

Therefore, the 32nd bit retrieved from the receiver FIFO will always

be “0” when valid (odd parity) ARINC 429 words are received.

RETRIEVING DATA

Once 32 valid bits are recognized, the receiver logic generates an

End of Sequence (EOS). Depending upon the state of control

register bits CR2-CR11, the received ARINC 32-bit word is then

checked for correct decoding and label matching before being

loaded into the 32 x 32 receive FIFO.

CR2(3) ARINC word CR6(9) ARINC word

FIFO

matches

bits 9,10

label

match

CR7,8 (10,11)

0

X

0

X

Load FIFO

1

No

0

X

Ignore data

1

Yes

0

X

Load FIFO

0

X

1

No

Ignore data

0

X

1

Yes

Load FIFO

1

Yes

1

No

Ignore data

1

No

1

Yes

Ignore data

1

No

1

No

Ignore data

1

Yes

1

Yes

Load FIFO

ARINC words which do not meet the necessary 9th and 10th

ARINC bit or label matching are ignored and are not loaded into

the receive FIFO. The following table describes this operation.

HOLT INTEGRATED CIRCUITS

5