Core1553BRT-EBR Enhanced Bit Rate 1553 Remote Terminal
mapping and interrupt vector extension functions
(Table 4).
Command Legalization Interface
The core checks the validity of all 1553EBR command
words. In RTL and netlist versions of the core, the logic
may be implemented externally to the core. The
command word is provided, and the logic must generate
the command valid input. The command legalization
interface also provides two strobes that are used to latch
the command value to enable it to be used for address
Backend Interface
The backend interface supports both synchronous
operation (to the core clock) and asynchronous
operation to backend devices (Table 5 on page 9).
Table 4 • Command Legalization Interface
Port Name
Type
Description
USEEXTOK
In
When '0', the core uses its own internal command valid logic, enabling all legal supported
mode codes and all sub-addresses.
When '1', the core disables its internal logic and uses the external CMDOKAY input for
command legality.
CMDVAL[11:0]
Out
Active Command
11
0: Non-broadcast
1: Broadcast
10
0: Receive
1: Transmit
[9:5]
[4:0]
Sub-address
Word count / mode code
These outputs are valid throughout the complete 1553EBR message. They can also be used to
steer data to particular backend devices. In particular, bit 11 allows non-broadcast and
broadcast messages to be differentiated.
CMDSTB
Out
In
Single clock cycle pulse that indicates CMDVAL has changed
CMDOKAY
Command word is okay (active high). The external logic must set this within 2 µs from the
CMDVAL output changing.
CMDOKOUT
ADDRLAT
Out
Out
Command word is okay output. When USEEXTOK = '0', the core outputs its internal
command word okay validation signal.
CMDVAL address latch enable output (active high) is used to latch the CMDVAL when it is
being used for an address mapping function. ADDRLAT should be connected to the enable of
a rising edge clock flip-flop.
INTLAT
Out
CMDVAL interrupt vector latch enable output (active high) is used to latch the CMDVAL when
it is being used for an extended interrupt vector function. INTLAT should be connected to the
enable of a rising edge clock flip-flop.
8
Advanced v1.1
ACTEL [ Actel Corporation ]
