HI-6130_16 Datasheet, PDF (24/296 Pages) Holt Integrated Circuits – 3.3V BC / MT / RT Multi-Terminal Device

HI-6130, HI-6131
resulting in a total of 4,096 possible combinations.
Terminal response to an illegal command sets “Message
Error” status and transmits Status Word only. If illegal
command detection is not used (that is, no “illegal”
entries in Illegalization Table), the terminal responds “in
form” to all valid commands.
5.11. RT1 and RT2 Descriptor Tables
For each RT, a host-initialized Descriptor Table in RAM
defines how the terminal responds to valid commands.
The table is comprised of 128 four-word descriptor
blocks. Each of 32 subaddresses and 32 mode code
values has one descriptor block for transmit and another
for receive. The descriptor table defines message
options (interrupt selections, data buffer mode, etc.) and
contains pointers to allocated data storage in RAM.
5.12. RT1 and RT2 Temporary Receive
Buffers
Remote Terminals RT1 and RT2 temporarily store
command and data words during message transaction.
At successful message completion, all data is transferred
to assigned subaddress buffers. This strategy prevents
valid data from being overwritten by incomplete or bad
data from a later message ending in error.
5.13. RT Message Data Buffers
Ordinary transmit and receive commands transact from
1 to 32 data words. The host allocates space in RAM
for storing transacted message data words as well as
message information words.
5.14. RT Storage for Mode Code
Commands
In addition to commands used for data transmit and
receive, MIL-STD-1553 also defines “mode code
commands” for command and control. These “mode
commands” transfer a single data word, or no data word
at all. The user has the option for storing mode command
data in RAM buffers assigned in the Descriptor Table, or
stored within the RT Descriptor Table itself. The second
option is often preferred for its simplicity.
6. HARDWARE FEATURES
6.1. Remote Terminal Address Inputs
The 5-bit Remote Terminal address is set using pins
RTA4:0. The RTAP input pin should be set or reset to
present matching odd parity. The state of the RT address
and parity pins is latched into the RT Operational Status
register upon rising edge on the MR master reset
input. The state of the LOCK input is latched into the
RT Operational Status register at the same time, and
controls whether or not the active terminal address
and parity in the RT Operational Status register can
be overwritten by host writes into the register. When
the LOCK input pin is high, autoinitialization cannot
overwrite the RT address value latched from the input
pins. Between Master Reset assertions, the state of the
RTA and RTAP input pins is “don’t care”. If the value
of RT address and parity in the RT Operational Status
register has parity error, terminal operation is disabled.
6.2. Dual Transceivers for MIL-STD-1553
Bus
Built-in bus transceivers provide direct interface
between the device and MIL-STD-1553 bus isolation
transformers. The transceivers convert digital data to
and from differential Manchester II encoded bus signals.
A pair of “transmit inhibit” input pins exercises direct
control over transmission for both buses.
6.3. Encoder and Decoders
The device uses separate Manchester II encoders and
decoders for each bus. Decoders check for proper
sync pulse and Manchester waveform, edge skew,
correct number of bits and parity. Encoders are used
for transmission. During transmit, each encoded word is
looped back through the bus decoder for error checking.
Receiver bus sampling is clocked at 50 MHz, providing
excellent tolerance to zero-crossing distortion.
6.4. Auto-Initialization Serial EEPROM
Interface
The device has an automatic self-initialization feature.
If self-initialization is enabled after MR master reset,
the device reads configuration settings from an external
serial EEPROM to initialize registers and RAM structures.
A method is provided to initially program or later modify
the external serial EEPROM by copying host-loaded
tables and register values to the serial EEPROM.
HOLT INTEGRATED CIRCUITS
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