CT2553-PCB Aeroflex Circuit Technology, CT2553-PCB Datasheet - Page 16

• Manufacturer Part Number: CT2553-PCB
• Description: Advanced Integrated Mux Aim Hybrid For Mil-std-1553 / Sae-as15531 In Pcb Style
• Manufacturer: Aeroflex Circuit Technology

RTU OPERATION
The RTU mode is selected by resetting the CT2553-PCB
and setting the appropriate bits in the Configuration
Register.
RTU MEMORY CONFIGURATION.
configures the memory by:
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.
TABLE 4 – TYPICAL RTU MEMORY MAP
SCDCT2553PCB Rev A Preliminary 7/13/06
0100
0101
0104
0105
0108-013F
0140-017F
01C0-01FF
0180-019F
01A0-01BF
0200-021F
0EE0-0EFF
0000-00FF
0F00-0FFF
HEX ADDRESS
1. Writing the start address of the Descriptor
2. Setting up the Look-Up Table as described
•
•
Stack into the Stack Pointer location and
below.
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
The user
16
RTU LOOK-UP TABLE.
Look-Up Table in order to map the Data Blocks based
upon
CT2553-PCB uses the T/
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/
= 0). The remaining 32 words are reserved for Data
Blocks associated with Transmit Commands (T/
= 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 internally using an 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
incoming
DATA BLOCK ASSIGNMENTS
INITIALIZE STACK POINTER
SET UP LOOK-UP TABLE(S)
WAIT FOR 1553 COMMAND
REGISTER TO RTU MODE
ISSUE RESET COMMAND
SET UP DATA BLOCKS
INITIALIZE INTERRUPT
SET CONFIGURATION
START REGISTER
1553
MASK REGISTER
START
R
Command
and Subaddress fields to
The RTU mode uses a
Aeroflex Plainview
Words.
R
R
The
bit
bit