hi-6131pqtf QuickLogic Corp, hi-6131pqtf Datasheet - Page 193

• Manufacturer Part Number: hi-6131pqtf
• Description: Mil-std-1553 / Mil-std-1760 3.3v Bc / Mt / Rt Multi-terminal Device
• Manufacturer: QuickLogic Corp

20.3.3. Broadcast Message Handling in Ping-
For MIL-STD-1553B Notice II compliance, a remote ter-
minal should be capable of storing data from broadcast
messages separately from non-broadcast message
data. Some applications may not include this require-
ment. The standard does not stipulate where data sepa-
ration should occur (e.g., within the RT or within the ex-
ternal host) so the device provides alternative strategies.
When the NOTICE2 bit in Configuration Register
1 is 1 and the BCSTINV bit is 0, ping-pong mode
subaddresses (or mode codes) will buffer data
words from broadcast and non-broadcast messages
separately. Broadcast message information and data
are stored in the broadcast data buffer; non-broadcast
message information and data are stored in ping-pong
buffers A and B. Since there is just one broadcast data
buffer, the NOTICE2 option treats broadcast messages
as exceptions to normal ping-pong mode. When using
the NOTICE2 option, broadcast data buffer servicing
should have high priority, because a closely following
broadcast message will overwrite the broadcast buffer.
Every mode command and subaddress (including
transmit subaddresses) must have an assigned val-
id broadcast data pointer when NOTICE2 is assert-
ed. When the NOTICE2 bit in Configuration Register 1
is 1 and the BCSTINV bit is 0, reception of a broadcast-
transmit message updates the Message Information
and Time-Tag Words for the assigned broadcast buffer,
but no data is transmitted on the bus. Since broadcast-
transmit is not allowed, multiple transmit subaddresses
may share a common “bit bucket” broadcast buffer. A
two word buffer is sufficient for storing the MIW and
Time-Tag Word.
When using ping-pong mode, there are two ways to han-
dle broadcast messages, when broadcast is enabled:
Option 1 for Ping-Pong Mode Broadcast Messages:
This option isolates broadcast message information
in the broadcast data buffer. If the descriptor Control
Word IBR bit and Interrupt Enable Register IBR bit are
both set, reception of broadcast messages generates
an INTMES host interrupt. To prevent data loss, the
broadcast data buffer must be serviced before the next
broadcast message occurs. Broadcast messages do not
affect non-broadcast message ping-pong; the Control
Word DPB bit does not toggle after broadcast message
completion.
Option 1 Setup:
NOTICE2 bit in Configuration Register 1 and sets the
IBR (Interrupt Broadcast Received) bit in descriptor
Pong Mode
At initialization, host asserts the
HOLT INTEGRATED CIRCUITS
HI-6130, HI-6131
193
Control Word(s). The IBR bit is asserted in the Interrupt
Enable Register.
When a broadcast command is received, message in-
formation and data is stored in the broadcast data buffer
and an INTMES interrupt is generated. The host must
read the Interrupt Log to determine the originating sub-
address (or mode code), then service the broadcast
data buffer for that subaddress (or mode code) before
another broadcast message to the same subaddress (or
mode code) arrives.
Option 2 for Ping-Pong Mode Broadcast Messages:
The second alternative stores both broadcast and non-
broadcast message information in the ping-pong data
buffers A and B. IWA interrupts can signal arrival of any
new message. The RT handles broadcast messages
just like non-broadcast messages, except the Mes-
sage Information Word BCAST bit is asserted to iden-
tify broadcast messages during host buffer servicing. All
messages toggle the Control Word DPB bit in message
post-processing. For Notice II compliance, separation
of broadcast and non-broadcast data occurs within the
host.
Option 2 Setup: At initialization, host negates the NO-
TICE2 bit in Configuration Register 1. If IWA interrupts
are used, the host asserts the descriptor Control Word
IWA (Interrupt When Accessed) bit 14 and the corre-
sponding bit is asserted in the Interrupt Enable Register.
Using this option, the IBR interrupt is probably not used.
The host typically services the ping-pong data buffers
A and B whenever a message is transacted. Using the
setup above, this occurs whenever the subaddress IWA
interrupt generates an INTMES interrupt output for the
host. The host must read the Interrupt Log to determine
the originating subaddress or mode code. The applica-
ble data buffer is indicated by the DPB bit in the Receive
Control Word. The Message Information Word BCAST
bit is asserted if the message was broadcast.