CT2553 Aeroflex Circuit Technology, CT2553 Datasheet - Page 16

• Manufacturer Part Number: CT2553
• Description: CT2553 / 2554 / 2555 / 2556 Advanced Integrated MUX (AIM) Hybrid FOR MIL-STD-1553
• Manufacturer: Aeroflex Circuit Technology

Aeroflex Circuit Technology
RTU OPERATION
The RTU mode is selected by resetting the
CT2553 and setting the appropriate bits in the
Configuration Register.
RTU MEMORY CONFIGURATION. The user
configures the memory by:
1. Writing the start address of the Descriptor
2. Setting up the Look-Up Table as described
If both map areas (A and B) are utilized, this
procedure must be performed for each area. Note
that the Stack Pointer and Look-Up Table
locations are fixed; Data Block(s) locations are
user-defined. Message blocks may be loaded
anywhere in the non-fixed areas of the shared
RAM. However, each data block may not cross a
256 word boundary (i.e., bit 8 of the starting
address of the message block must match bit 8 of
the address of the last word of the message
block). An example of a typical RTU Memory Map
is given in Table 4. Figure 19 shows the RTU
Initialization steps.
0100
0101
0104
0105
0108-013F
0140-017F
01C0-01FF
0180-019F
01A0-01BF
0200-021F
0EE0-0EFF
0000-00FF
0F00-0FFF
Stack into the Stack Pointer location and
below.
HEX ADDRESS
Table 4 – Typical RTU Memory Map
•
•
User Defined Areas
Fixed Areas
Descriptor Stack Pointer A
Reserved
Descriptor Stack Pointer B
Reserved
Spare
Look-Up Table A
Look-Up Table B
Data Block 1
Data Block 2
Data Block 3
Data Block 107
Descriptor Stack A
Descriptor Stack B
•
•
FUNCTION
16
RTU LOOK-UP TABLE. The RTU mode uses a
Look-Up Table in order to map the Data Blocks
based upon incoming 1553 Command Words.
The CT2553 uses the T/R and Subaddress fields
to address the Look-Up Table. Each Look-Up
Table (A and B) location contains a user-defined
Data Block Pointer to an associated Data Block
(See Figures 20 and 21).
The first 32 words of the Look-Up Table are
reserved for Data Blocks associated with Receive
Commands (T/R bit = 0). The remaining 32 words
are reserved for Data Blocks associated with
Transmit Commands (T/R bit = 1).
Mode Commands with data are mapped in the
same manner as non-mode commands. A
Synchronize With Data command maps to the
first or thirty-second Table entry (depending upon
subaddress: all 0's or all 1's), while a Transmit
Vector Word command points to the thirty-third or
sixty-fourth entry.
Note: The Data Block and Stack Pointers are
maintained
8-BIT-REGISTER for the HIGH BYTE and an
8-BIT COUNTER for the LOW BYTE; the high
byte remains constant (user value) while the low
byte will wrap around from FF(H) to 00(H). For
example: a current Pointer value of 10 FF(H)
will increment to 10 00(H) and not 11 00(H).
Figure 19 – RTU Initialization
DATA BLOCK ASSIGNMENTS
INITIALIZE STACK POINTER
SET UP LOOK-UP TABLE(S)
WAIT FOR 1553 COMMAND
REGISTER TO RTU MODE
ISSUE RESET COMMAND
INITIALIZE INTERRUPT
SET UP DATA BLOCKS
SET CONFIGURATION
START REGISTER
MASK REGISTER
internally
SCDCT2553 REV B 8/6/99 Plainview NY [phone]
START
using
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