HI-8581
LINE DRIVER OPERATION
REPEATER OPERATION
The line driver in the HI-8581 is designed to directly drive the ARINC
429 bus. The two ARINC outputs (TXA(OUT) and TXB(OUT))
provide a differential voltage to produce a +10 volt One, a -10 volt
Zero, and a 0 volt Null. Setting Control Register bit 13 to zero
causes a slope of 1.5 ms on the ARINC outputs; a one in Control
Register bit 13 causes a slope of 10 ms. Timing is set by on-chip
resistor and capacitor and tested to be within ARINC requirements.
No additional hardware is required to control the slope. The HI-8581
has 37.5 ohms in series with each line driver output.
Repeater mode of operation allows a data word that has been
received by the HI-8581 to be placed directly into its FIFO for
transmission. Repeater operation is similar to normal receiver
operation. In normal operation, either byte of a received data
word may be read from the receiver latches first by use of SEL
input. During repeater operation however, the lower byte of the
data word must be read first. This is necessary because, as the
data is being read, it is also being loaded into the FIFO and the
transmitter FIFO is always loaded with the lower byte of the data
word first. Signal flow for repeater operation is shown in the
Timing Diagrams section.
TXA(OUT)
ARINC BIT
TXB(OUT)
DATA
BIT 30
NULL
DATA
DATA
NULL
NULL
BIT 31
BIT 1
NEXT WORD
WORD GAP
BIT 32
DATA BUS
CWSTR
VALID
tCWSET
tCWHLD
tCWSTR
tEND/R
tEN
tD/R
tSELEN
tSELEN
tENSEL
tENSEL
tENEN
tDATAEN
tD/REN
tDATAEN
DATA BUS
tENDATA
tENDATA
HOLT INTEGRATED CIRCUITS
6
HOLTIC [ HOLT INTEGRATED CIRCUITS ]
