CT2554 Просмотр технического описания (PDF) - Aeroflex Corporation

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CT2554

CT2553 / 2554 / 2555 / 2556 Advanced Integrated MUX (AIM) Hybrid

Aeroflex Corporation 

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

Stack into the Stack Pointer location and

2. Setting up the Look-Up Table as described

below.

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

HEX ADDRESS

FUNCTION

0100

0101

0104

0105

0108-013F

0140-017F

01C0-01FF

0180-019F

01A0-01BF

0200-021F

•

•

0EE0-0EFF

0000-00FF

0F00-0FFF

Fixed Areas

Descriptor Stack Pointer A

Reserved

Descriptor Stack Pointer B

Reserved

Spare

Look-Up Table A

Look-Up Table B

User Defined Areas

Data Block 1

Data Block 2

Data Block 3

•

•

Data Block 107

Descriptor Stack A

Descriptor Stack B

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).

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).

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.

START

ISSUE RESET COMMAND

INITIALIZE STACK POINTER

SET UP LOOK-UP TABLE(S)

DATA BLOCK ASSIGNMENTS

SET UP DATA BLOCKS

INITIALIZE INTERRUPT

MASK REGISTER

SET CONFIGURATION

REGISTER TO RTU MODE

START REGISTER

WAIT FOR 1553 COMMAND

Figure 19 – RTU Initialization

Aeroflex Circuit Technology

16

SCDCT2553 REV B 8/6/99 Plainview NY (516) 694-6700

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