CT1995-20-2 - Aeroflex Incorporated

SCDCT1999 Rev C

DESCRIPTION

The Aeroflex-Plainview CT1999 design incorporates an ASIC and five Octal Buffers that accomplish the

dual redundant MIL-STD1553B Remote Terminal and/or Bus Controller Protocol Functions.

Buffering has been added to the most commonly used output signals on the CT1999, minimizing

external hardware requirements. The CT1999 connects directly to all Aeroflex-Plainview

Driver/Receiver Units.

FEATURES

❑Performs the Complete Dual-Redundant Remote Terminal and Bus Controller Protocol Functions of MIL-STD-1553B

❑Automatic Switchover to Superseding Input Commands

❑750mW Typical Power Consumption

❑+5V DC Operation

❑Full Military (-55°C to +125°C) Temperature Range

❑Direct Replacement for CT1602

❑Advanced Low Power VLSI Technology

❑Compatible with all Aeroflex-Plainview Driver/Receiver Units

❑Designed for Commercial, Industrial and Aerospace Applications

❑MIL-PRF-38534 compliant devices available

❑Aeroflex-Plainview is a Class H & K MIL-PRF-38534 Manufacturer

❑Packaging – Hermetic Ceramic

- Plug-In - 90 Pin, 2.4"L x 1.6"W x .225"Ht

- Flat Pack - 88 Lead, 2.4"L x 1.6"W x .225"Ht

CT1999

Remote Terminal and/or BUS Controller

www.aeroflex.com/Avionics

June 16, 2005

Figure 1 – BLOCK DIAGRAM (WITH TRANSFORMERS)

for MIL-STD-1553B

Encoder

Decoder

"0"

Decoder

"1"

Driver

Select

Enable

BUS "0"

BUS "1"

T/R

Hybrid

T/R

Hybrid

Internal

Highway

Control

Discrete

Output

Buffers

Internal

Highway

Buffer

SA & WC

Buffers

Interface

Unit

Control

Data I/O

Sub Address

Word Count

Outputs

Buffered

Descrete

Outputs

Unbuffered

Outputs

Control

Inputs

Terminal

Address

Inputs ASIC

CT1999

SCDCT1999 Rev C

ABSOLUTE MAXIMUM RATINGS

Parameter Min Max Units

VCC -0.3 7.0 V

Input or Output Voltage at any Pin -0.3 7.0 V

Operating (Free-Air) Temperature -55 +125 °C

Storage Case Temperature -65 +150 °C

RECOMMENDED DC OPERATING CONDITIONS

Parameter Test Conditions Min Typ Max Unit

VCC (Logic) 4.5 5.0 5.5 V

VIH High Level Input Voltage VCC = 5.0V 2.2 - - V

VIL Low Level Input Voltage VCC = 5.0V - - 0.7 V

ELECTRICAL CHARACTERISTICS

(TA = -55°C to +125°C)

Parameter Test Conditions Min Typ Max Unit Notes

VOH High Level Output Voltage VCC = 4.5V 2.4 - - V 4

VOL Low Level Output Voltage VCC = 4.5V - - 0.4 V 4

IIH High Level Input Current VCC = 5.5V,

VIN = 2.7V

-200

-25

-700

-400

µA

IIL Low Level Input Current VCC = 5.5V,

VIN = 0.4V

-400

-25

-900

-400

µA

ICC Supply Current VCC = 5.5V - - 20 mA 4

NOTES:

1/ RTAD 0/1/2/3/4 and RTADPAR ONLY.

2/ ALL Inputs and Bidirectionals other than those in Note 1.

3/ IOL max = 3mA / IOH max = -2mA TX INHIBIT 0/1 and TX DATA/DATA ONLY.

IOL max = 2mA / IOH max = -1mA – ALL remaining Outputs and Bidirectionals.

4/ Input Clock (running) = 6MHz, ALL remaining Inputs are Open and ALL Outputs and Bidirectionals have no load

5/ -20-3 only. RTAD0,1,3 and RTADPAR Input Threshold equals 1/2 Vcc ±5%.

CLOCK REQUIREMENTS

Parameter Range

Frequency: 6.0 MHz

Stability -55°C to +125°C: ±0.01% (100ppm)

Maximum Asymmetry: 48 - 52%

Rise/Fall Time: 10ns MAX

Output Level: Logic "0" 0.4V MAX

Logic "1" 2.4V MIN

SCDCT1999 Rev C

REMOTE TERMINAL OPERATION

Receive Data Operation

All valid data words associated with a valid receive data command word for the RT are passed to the subsystem.

The RT examines all command words from the bus and will respond to valid (i.e. correct Manchester, parity

coding etc.) commands which have the correct RT address (or broadcast address if the RT broadcast option is

enabled). When the data words are received, they are decoded and checked by the RT and, if valid, passed to the

subsystem on a word by word basis at 20µs intervals. This applies to receive data words in both Bus Controller to

RT and RT to RT messages. When the RT detects that the message has finished, it checks that the correct number

of words have been received and if the message is fully valid, then a Good Block Received signal is sent to the

subsystem, which must be used by the subsystem as permission to use the data just received.

The subsystem must therefore have a temporary buffer store up to 32 words long into which these data words can

be placed. The Good Block Received signal will allow use of the buffer store data once the message has been

validated.

If a block of data is not validated, then Good Block Received will not be generated. This may be caused by any

sort of message error or by a new valid command for the RT being received on another bus to which the RT must

switch.

Transmit Data Operation

If the RT receives a valid transmit data command addressed to the RT, then the RT will request the data words

from the subsystem for transmission on a word by word basis. To allow maximum time for the subsystem to

collect each data word, the next word is requested by the RT as soon as the transmission of the current word has

commenced.

It is essential that the subsystem should provide all the data words requested by the RT once a transmit sequence

has been accepted. Failure to do so will be classed by the RT as a subsystem failure and reported as such to the Bus

Controller.

Control of Data Transfers

This section describes the detailed operation of the data transfer mechanism between RT and subsystems. It covers

the operations of the signals

DTRQ

DTAK

, IUSTB, H/

GBR

NBGT

, TX/

during receive data and transmit

data transfers.

Figure 7 shows the operation of the data handshaking signals during a receive command with two data words.

When the RT has fully checked the command word,

NBGT

is pulsed low, which can be used by the subsystem as

an initialization signal. TX/

will be set low indicating a receive command. When the first data word has been

fully validated,

DTRQ

is set low. The subsystem must then reply within approximately 1.5µs by setting

DTAK

low. This indicates to the RT that the subsystem is ready to accept data. The data word is then passed to the

subsystem on the internal highway IH08-IH715 in two bytes using IUSTB as a strobe signal and H/

as the byte

indicator (high byte first followed by low byte). Data is valid about both edges of IUSTB. Signal timing for this

handshaking is shown in Figure 12.

If the subsystem does not declare itself busy, then it must respond to

DTRQ

going low by setting

DTAK

low

within approximately 1.5µs. Failure to do so will be classed by the RT as a subsystem failure and reported as such

to the Bus Controller.

It should be noted that IUSTB is also used for internal working in the RT.

DTRQ

being low should be used as an

enable for clocking data to the subsystem with IUSTB.

Once the receive data block has finished and been checked by the RT,

GBR

is pulsed low if the block is entirely

correct and valid. This is used by the subsystem as permission to make use of the data block if no

GBR

signal is

generated, then an error has been detected by the RT and the entire data block is invalid and no data words in it

may be used.

SCDCT1999 Rev C

If the RT is receiving data in an RT to RT transfer, the data handshaking signals will operate in an identical fashion

but there will be a delay of approx 70µs between

NBGT

going low and

DTRQ

first going low. See Figure 10.

Figure 6 shows the operation of the data handshaking signals during transmit command with three data words. As

with the receive command discussed previously,

NBGT

is pulsed low if the command is valid and for the RT.

TX/

will be set high indicating a transmit data command. While the RT is transmitting its status word, it

requests the first data word from the subsystem by setting

DTRQ

low. The subsystem must then reply within

approximately 13.5µs by setting

DTAK

low. By setting

DTAK

low, the subsystem is indicating that it has the data

word ready to pass to the RT. Once

DTAK

is set low by the subsystem,

DTRQ

should be used together with H/

and TX/

to enable first the high byte and then the low byte of the data word onto the internal highway

IH08-IH715. The RT will latch the data bytes during IUSTB, and will then return

DTRQ

high. Data for each byte

must remain stable until IUSTB has returned low. Signal timing for this handshaking is shown in Figure 11.

Additional Data Information Signals

At the same time as data transfers take place, a number of information signals are made available to the

subsystem. These are

INCMD

, the subaddress lines SA0-SA4, the word count lines WC0-WC4 and current word

count lines CWC0-CWC4. Use of these signals is optional.

INCMD

will go active low while the RT is servicing a valid command for the RT. The subaddress,

transmit/receive bit, and word count from the command word are all made available to the subsystem as

SA0-SA4, TX/

and WC0-WC4 respectively. They may be sampled when

INCMD

goes low and will remain

valid while

INCMD

is low.

The subaddress is intended to be used by the subsystem as an address pointer for the data block. Subaddress 0 and

31 are mode commands, and there can be no receive or transmit data blocks associated with these. (Any data word

associated with a mode command uses different handshaking operations. If the subsystem does not use all the

subaddresses available, then some of the subaddress lines may be ignored.

The TX/

signal indicates the direction of data transfer across the RT - subsystem interface. Its use is described

in the previous section.

The word count tells the subsystem the number of words to expect to receive or transmit in a message, up to 32

words. A word count of all 0s indicates a count of 32 words.

The current word count is set to 0 at the beginning of a new message and is incremented following each data word

transfer across the RT - subsystem interface. (It is clocked on the falling edge of the second IUSTB pulse in each

word transfer). It should be noted that there is no need for the subsystem to compare the word count and current

word count to validate the number of words in a message. This is done by the RT.

Subsystem Use Of Status Bits And Mode Commands

General Description

Use of the status bits and the mode commands is one of the most confusing aspects of MIL-STD-1553B. This is

because much of their use is optional, and also because some involve only the RT while others involve both the RT

and the subsystem.

The CT1999 allows full use to be made of all the Status Bits, and also implements all the Mode Commands. The

subsystem is given the opportunity to make use of Status Bits, and is only involved in Mode Commands which

have a direct impact on the subsystem.

The mode commands in which the subsystem may be involved are Synchronize, Sychronize with data word,

Transmit Vector Word, Reset and Dynamic Bus Control allocation. The Status Bits to which the subsystem has

access are Service Request, Busy, Dynamic Bus Control Acceptance, Terminal Flag, Subsystem Flag, and

Message Error Bit. Operation of each of these Mode Commands and of the Status Bits is described in the

following sections.

All other Mode Commands are serviced internally by the RT. The Terminal Flag and Message Error Status Bits

SCDCT1999 Rev C

and BIT Word contents are controlled by the RT; however the subsystem has the option to set the Message Error

Bit and to control the reset conditions for the Terminal Flag and Subsystem Flag Bits in the Status Word, and the

Transmitter Timeout, Subsystem Handshake, and Loop Test Fail Bits in the BIT Word.

Synchronize Mode Commands

Once the RT has validated the command word and checked for the correct address, the

SYNC

line is set low. The

signal WC4 will be set low for a Synchronize mode command (See Figure 16), and high for a Synchronize with

data word mode command (See Figure 15). In a Synchronize with data word mode command,

SYNC

remains low

during the time that the data word is received. Once the data word has been validated, it is passed to the subsystem

on the internal highway IH08-IH715 in two bytes using IUSTB as a strobe signal and H/

as the byte indicator

(high byte first followed by low byte).

SYNC

being low should be used on the enable to allow IUSTB to clock

synchronize mode data to the subsystem.

If the subsystem does not need to implement either of these mode commands, the

SYNC

signal can be ignored,

since the RT requires no response from the subsystem.

Transmit Vector Word Mode Command

Figure 14 illustrates the relevant signal timings for an RT receiving a valid Transmit Vector Word mode command.

The RT requests data by setting

VECTEN

low. The subsystem should use H/

to enable first the high byte and

then the low byte of the Vector word onto the internal highway IH08-IH715.

It should be noted that the RT expects the Vector word contents to be already prepared in a latch ready for enabling

onto the internal highway when

VECTEN

goes low. If the subsystem has not been designed to handle the Vector

word mode command, it will be the fault of the Bus Controller if the RT receives such a command. Since the

subsystem is not required to acknowledge the mode command, the RT will not be affected in any way by Vector

word circuitry not being implemented in the subsystem. It will however transmit a data word as the Vector word,

but this word will have no meaning.

Reset Mode Command

Figure 8 shows the relevant signal timings for an RT receiving a valid reset mode command. Once the command

word has been fully validated and serviced, the

RESET

signal is pulsed low. This signal may be used as a reset

function for subsystem interface

circuitry

Dynamic Bus Allocation

This mode command is intended for use with a terminal which has the capability of configuring itself into a bus

controller on command from the bus. The line

DBCREQ

cannot go true unless the

DBCACC

line was true at the

time of the valid command, i.e. tied low. For terminals acting only as RTs, the signal

DBCACC

should be tied

high (inactive), and the signal

DBCREQ

should be ignored and left unconnected.

Use of the Busy Status Bit

The Busy Bit is used by the subsystem to indicate that it is not ready to handle data transfers either to or from the

RT.

The RT sets the bit to logic one if the

BUSY

line from the subsystem is active low at the time of the second falling

edge of INCLK after

INCMD

goes low. This is shown in Figure 13. Once the Busy bit is set, the RT will stop all

receive and transmit data word transfers to and from the subsystem. The data transfers in the Synchronize with

data word and Transmit Vector word mode commands are not affected by the Busy bit and will take place even if

it has been set.

It should be noted that a minimum of 0.5µs subaddress decoding time is given to the subsystem before setting of

status bits. This allows the subsystem to selectively set the Busy bit if for instance one subaddress is busy but

others are ready. This option will prove useful when an RT is interfacing with multiple subsystems.

SCDCT1999 Rev C

Use of the Service Request Status Bit

The Service Request bit is used by the subsystem to indicate to the Bus Controller that an asynchronous service is

requested.

The timing of the setting of this bit is the same as the Busy bit and is shown in Figure 13. Use of

SERVREQ

has

no effect on the RT apart from setting the Service Request bit.

It should be noted that certain mode commands require that the last status word be transmitted by the RT instead

of the current one, and therefore a currently set status bit will not be seen by the Bus Controller. Therefore the user

is advised to hold

SERVREQ

low until the requested service takes place.

Use of the Subsystem Status Bit

This status bit is used by the RT to indicate a subsystem fault condition. If the subsystem sets

SSERR

low at any

time, the subsystem fault condition in the RT will be set, and the Subsystem Flag status bit will subsequently be

set. The fault condition will also be set if a handshaking failure takes place during a data transfer to or from the

subsystem. The fault condition is cleared on power-up or by a Reset mode command.

Dynamic Bus Control Acceptance Status Bit

DBCACC

, when set true, enables an RT to configure itself into a Bus Controller, if the subsystem has the

capability, by allowing

DBCREQ

to pulse true and BIT TIME 18 to be set in the status response. If Dynamic Bus

Control is not required then

DBCACC

must be tied high.

DBCACC

tied high inhibits

DBCREQ

and clears BIT

TIME 18 in the status response.

Bus Driver/Receiver Interface

Receive Data

The decoder chip requires two TTL signals, RXDATA and

RXDATA

, to represent the data coming in from the

bus. PDIN should be driven to a logic level ‘1’ when the bus waveform exceeds a specified positive threshold and

NDIN should be driven to a logic level ‘1’ when a specified negative threshold is exceeded. During the quiet

period on the bus both signals should be at the same logic level. All the bus receivers must be permanently

enabled, the selection of the bus in use is controlled within the ASIC.

Transmit Data

The signals generated by the encoder chip, TXDATA and

TXDATA

, are of the same format as the receive data.

The only difference is that the TTL signals are negative logic, e.g. the signal is active when on logic level "0". This

means that when the encoder is quiet both TXDATA and

TXDATA

are at logic level "1". Both the signals should

be used in conjunction with

TXINHIBIT 0

and

TXINHIBIT 1

. TX INHIBIT 0 and TX INHIBIT 1 enable the

appropriate driver when it should be transmitting. Figure 5 shows an example of a typical interface circuit between

the CT1995 and a driver/receiver unit.

SCDCT1999 Rev C

BUS CONTROL OPERATION

To enable its use in a bus controller the ASIC has additional logic within it. This logic can be enabled by pulling

the pin labelled RT/

low. Once the ASIC is in bus control mode, all data transfers must be initiated by the bus

control processor correctly commanding the ASIC via the subsystem interface. In bus control mode six inputs are

activated which in RT mode are inoperative and four signals with dual functions exercise the second function (the

first being for the RT operation).

To use the CT1995 as a 1553B bus control interface, the bus control processor must be able to carry out four basic

bus-related functions. Two inputs, BCOPA and BCOPB allow these four options to be selected. The option is then

initiated by sending a negative-going strobe on the

BCOPSTB

input.

BCOPSTB

must only be strobed low when

NDRQ

is high. This is particularly important when two options are required during a single transfer.

With these options all message types and lengths can be handled. Normal BC/RT exchanges are carried out in

ASIC option zero. This is selected by setting BCOPA and BCOPB to a zero and strobing

BCOPSTB

. On receipt

of the strobe, the CT1995 loads the command word from an external latch using

CWEN

and H/

. The command

word is transmitted down the bus. The TX/

bit is, however, considered by the ASIC as being its inverse and so

if a transmit command is sent to a RT (Figure 17), the ASIC in BC mode believes it has been given a receive

command. As the RT returns the requested number of data words plus its status, the BC carries out a full

validation check and passes the data into the subsystem using

DTRQ

DTAK

, H/

, IUSTB and CWC as in RT

operation. It also supplies

GBR

at the end of a valid transmission. Conversely, a receive command sent down the

bus is interpreted by the BC as a transmit command, and so the requisite data words are added to the command

word. See Figure 18.

For mode commands, where a single command word is required, option one is selected by strobing

BCOPSTB

when BCOPA is high and BCOPB is low. On receiving the strobe, the command word is loaded from the external

latch using

CWEN

and H/

, the correct sync and parity bits are added and the word transmitted (See Figure 20).

Mode commands followed by a data word requires option two. Option two, selected by strobing

BCOPSTB

while

BCOPA is low and BCOPB is high, loads a data word via

DWEN

and H/

, adds sync and parity and transmits

them to the bus (See Figure 21). If the mode code transmitted required the RT to return a data word, then selecting

option three by strobing

BCOPSTB

when BCOPA and BCOPB are both high will identify that data word and if

validated, output it to the subsystem interface using RMDSTB and H/

This allows data words resulting from

mode codes to be identified differently from ordinary data words and routed accordingly (See Figure 22). All

received status words are output to the subsystem interface using STATSTB and H/

In BC option three, if the signal

PASMON

is active, then all data appearing on the selected bus is output to the

subsystem using STATSTB for command and status words or RMDSTB for data words.

RT to RT transfers require the transmission of two command words. A receive command to one RT is

contiguously followed by a transmit command to the other RT. This can be achieved by selecting option one

followed by option zero for the second command. The strobe (

BCOPSTB

) for option zero must be delayed until

NDRQ

has gone low and returned high following the strobe for option one. The RT transmissions are checked and

transferred in the subsystem interface to the bus control processor (See Figure 19).

Note: For all BC operations, BCOPA and BCOPB must remain valid and stable for a minimum of 1µs following

the leading (negative going) edge of

BCOPSTB

PASSIVE MONITOR

The Monitor Mode may be utilized to analyze or collect all activities which occur on a selected bus. This is

initiated by selecting a bus, placing the unit in BC option three and setting

PASMON

low. All data appearing on

the selected bus is output to the subsystem using STATSTB for Command and Status Words or RMDSTB for Data

Words.

The Loop Test Enable signal must remain in the low state throughout the diagnostic cycle.

SCDCT1999 Rev C

PIN DESCRIPTION

Signal Hybrid

Sink or Source Signal Description

RX DATA 0/1 SINK Positive Date In - This should be a TTL description of the positive,

half of the Manchester code data on the bus. It should be driven to a

logic level "1" when a predetermined positive threshold is exceeded

on the bus.

RX DATA 0/1 SINK Negative Data In - This should be a TTL description of the negative

half of the Manchester code data on the bus. It should be driven to a

logic level "1" when a predetermined negative threshold is exceeded

on the bus.

TX INHIBIT 0/1 SOURCE Transmitter Enable - Goes low when the transmitter is transmitting.

Should be used to enable the bus drivers.

TX DATA SOURCE Positive Data Out - When this signal goes high the bus should be

driven positive.

TX DATA SOURCE Negative Data Out - When this signal goes high the bus should be

driven negative.

RTAD 0-4 SINK RT address lines - These should be hardwired by the user. RTAD4 is

the most significant bit.

RTADPAR SINK RT address parity line - This must be hardwired by the user to give

odd parity.

BCSTEN 0/1 SINK Recognition of Broadcast command enable - When low the

recognition of broadcast command is prevented on the specified bus.

6MCK SINK 6 Megahertz master clock.

IH 08

IH 19

IH 210

IH 311

IH 412

IH 513

IH614

IH715

SINK/SOURCE Internal Highway - Bi-directional 8 bit highway on which 16 bit

words are passed in two bytes. IH 715 is the most significant bit of

each byte, the most significant byte being transferred first. The

highway should only be driven by the subsystem when data is to be

transferred to the RT.

DTRQ SOURCE Data Transfer Request - Goes low to request a data transfer

between the ASIC and subsystem. Goes high at the end of the

transfer.

DTAK SINK Data Transfer Acknowledge - Goes low to indicate that the

subsystem is ready for the data transfer.

IUSTB SOURCE Interface Unit Strobe - This is a double pulse strobe used to transfer

the two bytes of data.

H/L SOURCE High/Low - Indicates which byte of data is on the internal highway.

Logic level "0" for least significant byte.

GBR SOURCE Good Block Received - Pulses low for 500ns when a block of data

has been received by the ASIC and has passed all the validity and

error checks.

SCDCT1999 Rev C

NBGT SOURCE New Bus Grant - Pulses low whenever a new command is accepted

by the ASIC.

TX/RX SOURCE Transmit/Receive - The state of this line informs the subsystem

whether it is to transmit or receive data The signal is valid while

INCMD is low.

INCMD SOURCE In Command - Goes low when the RT is servicing a valid command.

The subaddress and word count lines are valid while the signal is

low.

WC 0-4 SOURCE Word Count - These five lines specify the requested number of data

words to be received or transmitted. Valid when INCMD is low.

SA 0-4 SOURCE Sub Address - These five lines are a label for the data being

transferred. Valid when INCMD is low.

CWC 0-4 SOURCE Current Word Count - These five lines define which data word in

the message is currently being transferred.

SYNC SOURCE Synchronize - Goes low when a synchronize mode code is being

serviced.

VECTEN/DWEN SOURCE Vector Word Enable/DataWord Enable - In the RT mode, this

signal is provided to enable the contents of the vector word latch

(which is situated in the subsystem) onto the ASIC’s internal

highway. This signal, when in the Bus Controller mode, is used to

enable mode code data from the subsystem onto the internal

highway.

RESET SOURCE Reset - This line pulses low for 500ns on completion of the servicing

of a valid and legal mode command to reset remote terminal.

SSERR SINK Subsystem Error - By taking this line low, the subsystem can set the

Subsystem Flag in the Status Word.

BUSY SINK Busy - This signal should be driven low if the subsystem is not ready

to perform a data transfer to or from the ASIC.

SERVREQ SINK Service Request - This signal should be driven low to request an

asynchronous transfer and left low until the transfer has taken place.

INCLK SOURCE Internal Clock (2 MHz) - This is made available for

synchronization use by the subsystem if required. However, many of

the outputs to the subsystem are asynchronous.

EOT SOURCE End of Transmission - Goes low if a valid sync plus two data bits do

not appear in time to be contiguous with preceding word.

RTADER SOURCE Remote Terminal Address Error - This line goes low if an error is

detected in the RT address parity of the selected receiver. Any

receiver detecting an error in the RT address will turn itself off.

HSFAIL SOURCE Handshake Failure - This line pulses low if the allowable time for

DTAK response has been exceeded during the ASIC/subsystem data

transfer handshaking.

PIN DESCRIPTION (con’t)

Signal Hybrid

Sink or Source Signal Description

SCDCT1999 Rev C

LSTCMD/CWEN SOURCE Last Command/Command Word Enable - This line pulses low

when servicing a valid and legal mode command to transmit last

command. When in RT mode this line must not be used to enable

data from the subsystem. This line also pulses low, when in the Bus

Control mode, when a command word is required for transmission.

STATEN/STATSTB SOURCE Status Enable/Status Strobe - This line pulses low to enable the

status word onto the internal highway for transmission. When in RT

mode this line must not be used to enable data from the subsystem.

This line also pulses high, when in the Bus Control mode, to strobe

received status words into the subsystem. When PASMON is true

this line pulses high for Command and Status words.

BITEN/RMDSTB SOURCE Built In Test Enable/Receive Mode Data Strobe - This line pulses

low when servicing a valid and legal mode command to transmit the

internal BIT word. This signal is for information only and must not

be used to enable data from the subsystem. This line also pulses high

when in the Bus Control mode when mode data is received to be

passed to the subsystem and when data is passed to the subsystem

during PASMON.

DWSYNC SOURCE Data Word Sync - This line goes low if a data word sync and two

Manchester biphase bits are valid.

CMSYNC SOURCE Command Word Sync - This line goes low if a command word sync

and two Manchester biphase bits are valid.

NDRQ SOURCE No Data Required - This line goes low if the encoder transmit buffer

is full i.e. another word is going to be transmitted. This signal is for

information only and must not be used to enable data from the

subsystem.

PASMON SINK Passive Monitor - When functioning as a Bus Controller this line

acts as a passive monitor select. The active going edge of this line

will cause the REQBUS lines to be latched and that bus, now

selected will be monitored so long as PASMON remains low. All

traffic on the bus will be handed, after validation, to the subsystem

via STATSTB for status and commands words, and RMDSTB for

data words.

BCOPSTB SINK Bus Controller Operation Strobe - When functioning as a Bus

Controller a low going pulse on this line will initiate the selected bus

controller operation on the requested bus, using BCOPA&B and

REQBUSA&B.

BCOP A SINK Bus Control Operation A - Least significant bit of the bus

controller operation select lines.

BCOP B SINK Bus Control Operation B - Most significant bit of the bus controller

operation select lines.

REQBUS A SINK/SOURCE Request Bus A - This line, when in RT mode, is the least significant

bit of the bus request lines which specify the origin of the command,

ie. they are sources. When in BC mode these lines are sinks and

specify which bus is to be used for the next command.

PIN DESCRIPTION (con’t)

Signal Hybrid

Sink or Source Signal Description

SCDCT1999 Rev C

REQBUS B SINK/SOURCE Request Bus B - Most significant bit of the bus request lines (See

REQBUS A above for description).

RT/BC SINK Remote Terminal/Bus Control - This line when high causes the

ASIC to function as a remote terminal. When low the ASIC

functions as a bus controller or passive monitor.

DBCACC SINK Dynamic Bus Control Accept - This line should be permanently

tied low if a subsystem is able to accept control of the bus if offered.

LTFAIL SOURCE Loop Test Fail - This line goes low if any error in the transmitted

waveform is detected or if any parity error in the hardwired RT

address is detected.

ERROR SOURCE Error - This line latches low if a Manchester or parity error is

detected. It is reset by the next CMSYNC (RT mode) and also by

RTO in the BC mode.

RTO SOURCE Reply Time Out - This signal will pulse low whenever the reply

time for a transmitting terminal has been exceeded. This line is

intended for the bus controller use.

TXTO SOURCE Transmitter Time Out - This line goes true if the transmitter time

out limits are exceeded.

PARER SOURCE Parity Error - This line will pulse low if a parity error is detected by

the decoder.

MANER SOURCE Manchester Error - This line will pulse low if a Manchester error is

detected by the decoder.

DBCREQ SOURCE Dynamic Bus Control Request - This line will pulse low when the

status reply for a mode code Dynamic Bus Control has finished

where the accept bit was set.

VA L D SOURCE Valid Data - This line will pulse low when a valid data word is

received.

PIN DESCRIPTION (con’t)

Signal Hybrid

Sink or Source Signal Description

SCDCT1999 Rev C

Controller to

RT Transfer

Receive

Command

Data

Word

Data

Word . . . . Data

Word . . Status

Word

§Command

Word

RT to

Controller

Transfer

Transmit

Command . . Status

Word

Data

Word

Data

Word . . . . Data

Word

§Command

Word

RT to RT

Transfer

Receive

Command

Transmit

Command . . Status

Word

Data

Word

Data

Word . . . . Data

Word . . Status

Word

§Command

Word

Mode Command

Without Data

Word

Mode

Command . . Status

Word

§Command

Word

Mode Command

With Data

Word

(Transmit)

Mode

Command . . Status

Word

Data

Word

§Command

Word

Mode Command

With Data

Word

(Receive)

Mode

Command

Data

Word . . Status

Word

§Command

Word

NOTE: § = Intermessage Gap

. . = Response Time

Figure 1 – TYPICAL MESSAGE FORMATS

T/R

Bit Mode Code Function Associated

Data Word

Broadcast Command

Allowed

1 00000 Dynamic Bus Control No No

1 00001 Synchronize No Yes

1 00010 Transmit Status Word No No

1 00011 Initiate Self Test No Yes

1 00100 Transmitter Shutdown No Yes

1 00101 Override Transmitter Shutdown No Yes

1 00110 Inhibit Terminal Flag Bit No Yes

1 00111 Override lnhibit Terminal Flag Bit No Yes

1 01000 Reset Remote Terminal No Yes

1 01001 Reserved No TBD

↓ ↓ ↓ ↓

1 01111 Reserved No TBD

1 10000 Transmit Vector Word Yes No

0 10001 Synchronize Yes Yes

1 10010 Transmit Last Command Yes No

1 10011 Transmit BlTWord Yes No

0 10100 Selected Transmitter Shutdown Yes Yes

0 10101 Override Selected Transmitter

Shutdown

Ye s Ye s

1 or 0 10110 Reserved Yes TBD

↓ ↓ ↓ ↓

1 or 0 11111 Reserved Yes TBD

Figure 2 – ASSIGNED MODE CODES

SCDCT1999 Rev C

BIT TIMES 1234567891011121314151617181920

COMMAND

WORD 515 5 1

SYNC REMOTE TERMINAL

ADDRESS T/R SUBADDRESS/MODE DATA WORD

COUNT/MODE CODE P

DATA WORD 16 1

SYNC DATA P

1LSB 20

BIT WORD 1514131211109876543210 P

SYNC

STATUS

WORD 5 111 3 11111 1

SYNC REMOTE TERMINAL

ADDRESS

RESERVED

Note: T/R – Transmit/Receive

P – Parity

Figure 3 – WORD FORMAT

Transmitter Timeout on Bus 3

Transmitter Timeout on Bus 2

Transmitter Timeout on Bus 1

Transmitter Timeout on Bus 0

Bus 3 Shutdown

Bus 2 Shutdown

Bus 1 Shutdown

Bus 0 Shutdown

Broadcast Transmit Data Received

Word Count High

Word Count Low

Illegal Mode Command

Mode T/R Bit Wrong

Loop Test Failure

Subsystem Handshake Failure

Transmitter Timeout Flag

Message Error

Instrumentation

Service Request

Broadcast Command Received

Busy

Subsystem Flag

Dynamic Bus Control Acceptance

Terminal Flag

Parity

SCDCT1999 Rev C

1553B

BUS "B"

1553B

BUS "A"

ACT4453

Driver/

Receiver 1

ACT4453

Driver/

Receiver 0

TX DATA OUT

RX DATA IN

TX DATA OUT

RX DATA IN

XFR0

XFR1

TX DATA OUT

RX DATA IN

TX DATA OUT

RX DATA IN

RX DATA OUT

TX DATA IN

RX DATA OUT

TX DATA IN

RX DATA OUT

TX INHIBIT "1"

CT1995

RX DATA 0

TX DATA

TX INHIBIT "0"

TX INHIBIT "1"

TX INHIBIT "0"

1MHz

NRZ

Manchester

Data

Bi-Phase

Clock

(+) -

(0) -

(+) -

(0) -

(+) -

(0) -

(-) -

One Bit Time

RX DATA 1

Figure 4 – DATA ENCODING

Figure 5 – EXAMPLE OF AN INTERFACE BETWEEN THE CT1995 AND DRIVER/RECEIVER

SCDCT1999 Rev C

Figure 6 – TRANSFER OF THREE DATA WORDS FROM RT 03 TO BC

Figure 7 – TRANSFER OF TWO DATA WORDS FROM BC TO RT 03

Figure 8 – MODE COMMAND RESET REMOTE TERMINAL

PDIN

NBGT

INCMD

DTRQ

IUSTB

H/L

GBR

EOT

PDIN

NBGT

INCMD

DTRQ

IUSTB

H/L

GBR

EOT

PDIN

NBGT

INCMD

DTRQ

IUSTB

H/L

RESET

EOT

SCDCT1999 Rev C

Figure 9 – RT TO RT TRANSFER OF FOUR DATA WORDS (THIS RT SENDING THE DATA)

Figure 10 – RT TO RT TRANSFER OF FOUR DATA WORDS (THIS RT RECEIVING THE DATA)

PDIN

NBGT

INCMD

DTRQ

IUSTB

H/L

GBR

EOT

PDIN

NBGT

INCMD

DTRQ

IUSTB

H/L

GBR

EOT

SCDCT1999 Rev C

DTAK

IUSTB

H/L

CWC0-CWC4

DTRQ

Subsystem Reply Time < 13.5µs

Don’t Care

250 nsec 250 nsec

500 nsec

Valid Incremented

Enable High Byte of TX

Data on Internal

Highway

Enable Low Byte of

TX Data on Internal

Highway

DTAK

IUSTB

H/L

CWC0-CWC4

DTRQ

Subsystem Reply Time < 1.5µs

Don’t Care

250 nsec 250 nsec

500 nsec

IncrementedValid

Low Byte Valid

High Byte Valid

Internal

Highway

Figure 11 – HANDSHAKING FOR TX DATA TRANSFERS

Figure 12 – HANDSHAKING FOR RX DATA TRANSFERS

SCDCT1999 Rev C

SA4-SA0

NBGT

1.0µs Minimum

Valid

Previous command value

BUSY Latch here

TX/RX

WC4-WC0

CWC4-CWC0

INCMD

INCLK

NBGT

INCMD

VECTEN

H/L

Enable high byte of

vector word onto

internal highway

Enable low byte of

vector word onto

internal highway

}

1.5µs

approx.

}

Figure 14 – TRANSMIT VECTOR WORD COMMAND

Figure 13 – NEW COMMAND INITIALIZATION

SCDCT1999 Rev C

Figure 15 – SYNCHRONIZE (WITH DATA) MODE COMMAND

Figure 16 – SYNCHRONIZE (NO DATA) MODE COMMAND

PDIN

NBGT

INCMD

SYNC

ILUSTB

EOT

WC4

H/L

0 0

PDIN

NBGT

INCMD

SYNC

EOT

WC0

0 0

IUSTB

SCDCT1999 Rev C

Figure 17 – BUS CONTROLLER SENDING COMMAND TO RT 10001 TO TRANSMIT TWO DATA WORDS

BCOPSTB

NDRG

CWEN

H/L

IUSTB

C/D

NBGT

INCMD

VALC

VALD

STATSTB

DTRG

GBR

EOT

RTO

PDIN

SCDCT1999 Rev C

Figure 18 – BUS CONTROLLER SENDING COMMAND TO RT 10001 TO RECEIVE TWO DATA WORDS

BCOPSTB

NDRG

CWEN

H/L

IUSTB

C/D

NBGT

INCMD

VALC

VALD

STATSTB

DTRG

GBR

EOT

RTO

PDIN

SCDCT1999 Rev C

BCOPSTB

BCOPA

BCOPB

NDRG

CWEN

H/L

IUSTB

C/D

TxSTB

NBGT

INCMD

VALC

VALD

STATSTB

DTRG

CWC0

CWC1

TREQ

GBR

EOT

TXEN

PDOUT

RTO

IH715

IH614

IH613

IH412

IH311

IH210

IH19

IH06

PDIN

Figure 19 – BUS CONTROLLER COMMANDING RT 10001 TO TRANSMIT TWO DATA WORDS AT RT 00001

SCDCT1999 Rev C

Figure 20 – BUS CONTROLLER SENDING MODE COMMAND TRANSMIT

STATUS WORD MODE CODE 00010

Figure 21 – BUS CONTROLLER SENDING MODE COMMAND

SYNCHRONIZE MODE CODE 10001

Figure 22 – BUS CONTROLLER SENDING MODE COMMAND TRANSMIT

VECTOR MODE CODE 10000

BCOPSTB

NDRQ

H/L

STATSTB

BCOPB

PDIN

BCOPA

CWEN

TXSTB

BCOPSTB

H/L

BCOPB

PDIN

BCOPA

CWEN

DWEN

BCOPSTB

H/L

BCOPB

PDIN

BCOPA

STATSTB

RMDSTB

SCDCT1999 Rev C

PIN vs FUNCTION - CT1995

Pin # Function Pin # Function Pin # Function

1 NC 31 REQBUS B 61 ERROR

2 CWC0 (LSB) 32 REQBUS A 62 LTFAIL

3 SA4 (MSB) 33 COMMON & CASE 63 MANER

4 SA3 34 NC 64 PARER

5 SA2 35 NC 65 VALD

6 CWC4 (MSB) 36 NC 66 RTADER

7 CWC3 37IH 08 (LSB) 67RX DATA 1

8 CWC2 38IH19 68RX DATA

9 CWC1 39 IH210 69 +5 VIN

10 GBR 40 IH311 70 TX INHIBIT 1

11 H/L 41 IH412 71 TX INHIBIT 0

12 STATEN/STATSTB 42 IH513 72 TX DATA

13 EOT 43 IH614 73 TX DATA

14 SA1 44 IH715 (MSB) 74 SERVREQ

15 SA0 (LSB) 45 NC 75 TXTO

16 INCMD 46 NC 76 DBCACC

17 TX/RX 47 RTADPAR 77 RESET

18 DTRQ 48 RTAD0 (LSB) 78 RT/BC

19 VECTEN/DWEN 49 RTAD1 79 DBCREQ

20 NBGT 50 RTAD2 80 HSFAIL

21 SYNC 51 RTAD3 81 LSTCMD/CWEN

22 INCLK 52 RTAD4 (MSB) 82 BITEN/RMDSTB

23 IUSTB 53 CMSYNC 83 BUSY

24 NC 54 DWSYNC 84 WC4 (MSB)

25 DTAK 55 BCSTEN 0 85 WC3

26BCOPA 56RX DATA 0 86WC0 (LSB)

27 BCOPSTB 57 RX DATA 0 87 SSERR

28 BCOP B 58 BCSTEN 1 88 WC2

29 PASMON 59 RTO 89 WC1

30 NDRQ 60 6 MCK 90 NC

SCDCT1999 Rev C

CERAMIC COFIRED 90-Pin PLUG IN PACKAGE OUTLINE

Lead 1 & ESD

Designator

.100

1.100

TYP

2.200

2.100

Pin 43 Pin 45

Pin 44

Pin 2

Pin 3

.135

.050

TYP

1.300

.090

.135

Pin 1

Pin 48 Pin 46

Pin 47

Pin 88

Pin 90

Pin 89

.018 DIA

TYP

2.400

MAX

1.600

MAX

.200

MIN

.225

MAX

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www.aeroflex.com info-ams@aeroflex.com

Aeroflex Microelectronic Solutions reserves the right to

change at any time without notice the specifications, design,

function, or form of its products described herein. All

parameters must be validated for each customer's application

by engineering. No liability is assumed as a result of use of

this product. No patent licenses are implied.

SCDCT1999 Rev C

Our passion for perform ance is defined by three

attributes represented by these thre e icons:

solution-minded, perform an ce-d riven an d custo m er-fo cuse d

ORDERING INFORMATION

Model Number Master Reset

Time Constant Package

CT1995-20 2.7 ms 1.6" x 2.4" Ceramic Plug In

CT1995-20-2 2.7 ms

CT1995-20-3 1200 µs

NOTE:

1. TTL and CMOS RT Address Thresholds. Refer to Recommended DC Operating Conditions, page 2.