7005 데이터 시트보기 (PDF) - Aeroflex Corporation

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7005

ACT7005/7006 Single Package Solution Dual Transceiver, Protocol, Subsystem

Aeroflex Corporation 

described below are available and are essentially

independent. Any, all, or none may be selected.

Also, reporting of faults by the subsystem requires

that SSERR be latched (not pulsed) low until the

fault is cleared.

Resetting SSF and TF on Receipt of Valid

Commands

If ENABLE is selected and the other three option

lines are held high, then the Status Word Register

will be reset on receipt of any valid command with

the exception of Transmit Status and Transmit Last

Command. Note that in this mode, the TF will never

be seen in the Status Word, and the SSF will only be

seen if SSERR is latched low. Also note that the SSF

will not be seen in response to Transmit Status or

Transmit Last Command if the preceding Status

Word was clear, regardless of actions taken on the

SSERR line after the clear status transmission.

Status Register Update at Fault Occurrence

If STATUS UPDATE is selected (held low), then the

TF or SSF will appear in response to a Transmit

Status or Transmit Last Command issued as the first

command after the fault occurs. Any other command

(except as noted in the Preserving the BIT Word

section) will reset the TF and SSF. Repeated

Transmit Status or Transmit Last Command

immediately following the fault will continue to show

the TF and/or SSF in the Status Word. Note that this

behavior may not meet the "letter-of-the-spec" as

described in MIL-STD-1553B, but is considered the

"preferred" behavior by some users.

TF and SSF Reporting in the Next Status

Word – After the Fault

If NEXT STATUS is selected (held low), then the TF

or SSF will appear in response to the very next valid

command after the fault except for Transmit Status

or Transmit Last Command. The flag(s) will be reset

on receipt of any valid command following the status

transmission with the flag(s) set except for Transmit

Status, Transmit Last Command, or as noted in the

following section on Preserving the BIT Word.

Preserving the BIT Word

In order to preserve the Transmitter Timeout Flag,

Subsystem Handshake Failure, and Loop Test

Failure Bits in the BIT Word, it is necessary to select

BIT DECODE (hold it low). This will prevent resetting

those bits if the Transmit Bit Word Mode Command

immediately follows the fault or follows a Transmit

Last Command or Transmit Status immediately

following the fault. It will also prevent resetting the TF

and SSF Bits in the Status Word. Any other valid

commands will cause those BIT Word Bits and the

Status Word Bits to be reset.

Aeroflex Circuit Technology

12

SCD7005 REV B 8/2/01 Plainview NY (516) 694-6700

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