HI-8582, HI-8583
FUNCTIONAL DESCRIPTION (cont.)
DATA TRANSMISSION
When ENTX goes high, enabling transmission, the FIFO
positions are incremented with the top register loading into the
data transmission shift register. Within 2.5 data clocks the first
data bit appears at TXAOUT and TXBOUT. The 31 or 32 bits in
the data transmission shift register are presented sequentially to
the outputs in the ARINC 429 format with the following timing:
HIGH SPEED
10 Clocks
5 Clocks
5 Clocks
40 Clocks
LOW SPEED
80 Clocks
40 Clocks
40 Clocks
320 Clocks
The HI-8582 has 37.5 ohms in series with each line driver output.
The HI-8583 has 10 ohms in series. The HI-8583 is for applications
where external series resistance is needed, typically for lightning
protection devices.
REPEATER OPERATION
Repeater mode of operation allows a data word that has been
received by the HI-8582/HI-8583 to be placed directly into the
transmitter FIFO. 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 transmitter FIFO which is always
loaded with the lower byte of the data word first. Signal flow for
repeater operation is shown in the Timing Diagrams section.
ARINC DATA BIT TIME
DATA BIT TIME
NULL BIT TIME
WORD GAP TIME
The word counter detects when all loaded positions have been
transmitted and sets the transmitter ready flag, TX/R, high.
HI-8582-10 and HI-8583-10
TRANSMITTER PARITY
The parity generator counts the Ones in the 31-bit word. If
control register bit CR12 is set low, the 32nd bit transmitted will
make parity odd. If the control bit is high, the parity is even.
Setting CR4 to a Zero bypasses the parity generator, and allows
32 bits of data to be transmitted.
The HI-8582-10/HI-8583-10 options are similar to the HI-8582/
HI-8583 with the exception that they allow an external 10 Kohm re-
sistor to be added in series with each ARINC input without affect-
ing the ARINC input thresholds. This option is especially useful in
applications where lightning protection circuitry is also required.
Each side of the ARINC bus must be connected through a
10 Kohm series resistor in order for the chip to detect the correct
ARINC levels. The typical 10 volt differential signal is translated
and input to a window comparator and latch. The comparator lev-
els are set so that with the external 10 Kohm resistors, they are
just below the standard 6.5 volt minimum ARINC data threshold
and just above the standard 2.5 volt maximum ARINC null thresh-
old.
Please refer to the Holt AN-300 Application Note for additional
information and recommendations on lightning protection of Holt
line drivers and line receivers.
SELF TEST
If control register bit CR5 is set low, the transmitter serial output
data are internally connected to each of the two receivers,
bypassing the analog interface circuitry. Data is passed
unmodified to receiver 1 and inverted to receiver 2. Taking TEST
high forces TXAOUT and TXBOUT into the null state regardless
of the state of CR5.
SYSTEM OPERATION
The two receivers are independent of the transmitter.
Therefore, control of data exchanges is strictly at the option of
the user. The only restrictions are:
1. The received data will be overwritten if the receiver FIFO
is full and at least one location is not retrieved before the next
complete ARINC word is received.
2. The transmitter FIFO can store 32 words maximum and
ignores attempts to load additional data if full.
HIGH SPEED OPERATION
The HI-8582 and HI-8583 may be operated at clock frequencies
beyond that required for ARINC compliant operation. For operation
at Master Clock (CLK) frequencies up to 5MHz, please contact
Holt applications engineering.
POWER SUPPLY SEQUENCING
The power supplies should be controlled to prevent large currents
during supply turn-on and turn-off. The recommended sequence is
V+ followed by V
DD
, always ensuring that V+ is the most positive
supply. The V- supply is not critical and can be asserted at any time.
LINE DRIVER OPERATION
The line driver in the HI-8582/HI-8583 are designed to directly
drive the ARINC 429 bus. The two ARINC outputs (TXAOUT
and TXBOUT) provide a differential voltage to produce a +10 volt
One, a -10 volt Zero, and a 0 volt Null. Control register bit CR13
controls both the transmitter data rate, and the slope of the
differential output signal. No additional hardware is required to
control the slope. Programming CR13 to Zero causes a
100 kbits/s data rate and a slope of 1.5 µs on the ARINC outputs;
a One on CR13 causes a 12.5 kbit/s data rate and a slope of
10 µs. Timing is set by on-chip resistor and capacitor and tested
to be within ARINC requirements.
MASTER RESET (MR)
On a Master Reset data transmission and reception are immedi-
ately terminated, all three FIFOs are cleared as are the FIFO flags
at the device pins and in the Status Register. The Control
Register is not affected by a Master Reset.
HOLT INTEGRATED CIRCUITS
7
HOLTIC [ HOLT INTEGRATED CIRCUITS ]
