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eroflex circuit t echnolo gy ? data bus modules for the future ? scd1995 rev a 11/21/01 features performs the complete dual-redundant remote terminal, bus controller protocol and passive monitor functions of mil-std-1553b mil-prf-38534 compliant circuits available 50 mw typical power consumption small size available in ceramic plug-in package configuration compatible with all act driver/receiver units 5v dc operation full military (-55c to +125c) temperature range 1 general description the CT1995 series is a monolithic implementation of the mil-std-1553b bus controller, remote terminal and passive monitor functions. all protocol functions of mil-std-1553b are incorporated and a number of options are included to improve flexibility. these features include programming of the status word, illegalizing specific commands and an indepe ndent loop back self-test which is initiated by the subsystem. this unit is directly compatible with all transceivers and microprocessor interfaces such as the ct1611 and ct1800 produced by aeroflex incorporated. encoder decoder "o" decoder "1" driver select & enable bus "0" bus "1" t/r hybrid t/r hybrid internal highway control interface unit program sub address & word count outputs discrete outputs control inputs terminal address inputs block diagram (with transformers) CT1995 mil-std-1553b remote terminal, bus controller, or passive monitor hybrid with status word control CT1995 series inputs status word control circuit technology www.aeroflex.com
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 2 absolute maximum ratings parameter range units supply voltage (v dd ) -0.3 to +7.0 v input or output voltage at any pad -0.3 to (v dd + 0.3) v storage case temperature -65 to +150 c recommended dc operating conditions parameter min typ max unit notes vcc power supply voltage vcc 4.5 5.0 5.5 v- v ih high level input voltage, vcc = 5v 2.2 - - v 1,2,5 v il low level input voltage, vcc = 5v - - 0.7 v 1,2,5 mr tc internal master reset time constant CT1995-20 CT1995-20-2 CT1995-20-3 2.43 2.43 180 - - - 2.97 2.97 220 ms ms s - electrical characteristics (t a = -55
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 3 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 20 s 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 receiv ed signal is sent to the s ubsystem, which must be used by the subsystem as permission to use the data just received. the subsystem must therefore have a temporary buffer stor e 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 t he 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 the rt and subsystems. it covers the operations of the signals dtrq , dtak , iustb, h/l , gbr , nbgt , tx/rx 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/rx will be set low indicating a receive comm and. when the first data word has been fully validated, dtrq is set low. the subsystem must then reply within approximately 1.5 s 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/l 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 1.5 s. 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. 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 70 s 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/rx 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 13.5 s 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/l and tx/rx 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.
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 4 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/rx 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 handshak ing operations. if the sub system does not use all the subaddresses available, then some of the subaddress lines may be ignored. the tx/rx 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 CT1995 allows full use to be made of all the status bits, and also implements all the mode commands. external programming of the terminal flag and subsystem flag bits plus setting of the message error bit on reception of an illegal command when externally decoded is available. the sub system 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 t he subsystem may be involved ar e synchronize, sychronize with data word, transmit vector word, reset and dynamic bus control acceptance. the status bits to which the subsystem has access, or control 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 and bit word contents are controlled by the rt; however the sub system 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 hands hake, 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 wo rd has been validated, it is pa ssed to the subsystem on the internal highway ih08-ih715 in two bytes using iustb as a strobe signal and h/l 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 respons e 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/l to enable first the high byte and then the low byte of the vector word onto the internal highway ih08-ih715.
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 5 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 w ill 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 r eset 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 lo w 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 t he busy bit and will take pl ace even if it has been set. it should be noted that a minimum of 0.5 s 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. 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 w ill be set, and t he subsystem flag status bit w ill subsequentl y 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 capab ility, 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.
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 6 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. 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/bc 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/l the command word is transmitted down the bus. the tx/rx 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/l , 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/l , 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/l , 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/l. 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/l . 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 1 s 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.
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 7 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. 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.
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 8 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 t he 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. 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 . pin description (cont.) signal hybrid sink or source signal description
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 9 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. pas m o n 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. bcopa sink bus control operation a - least significant bit of the bus controller operation select lines. bcopb sink bus control operation b - most significant bit of the bus controller operation select lines. reqbus a sink/source request bus a - this line,wwhen 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. reqbus b sink/source request bus b - most significant bit of the bus request lines. (see 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. lt fa i l 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 ou t - this line goes true if the transmitter time out limits are exceeded. par e r 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. pin description (cont.) signal hybrid sink or source signal description
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 10 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. vald source valid data - this line will pulse low when a valid data word is received. 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. pin description (cont.) signal hybrid sink or source signal description
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 11 next controller to rt transfer receive command data word data word . . . . data word . . status word command word rt to controller transfer next tr a n s m i t command . . status word data word data word . . . . data word command word next rt to rt transfer receive command tr a n s m i t command . . status word data word data word . . . . data word . . status word command word mode command without data word next mode command . . status word command word mode command with data word (transmit) next mode command . . status word data word command word mode command with data word (receive) next 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
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 12 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 data p 1 lsb 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 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 figure 3 ? word count
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 13 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 tx data in rx data out rx data out tx data in tx data in rx data out tx inhibit "1" CT1995 rx data 0 rx data 0 tx data tx data tx inhibit "0" tx inhibit "1" tx inhibit "0" figure 5 ? example of an interface between the CT1995 and driver/receiver 1mhz nrz manchester figure 4 ? data encoding data = bi-phase clock (+) - (0) - (+) - (0) - (+) - (0) - (-) - one bit time rx data 1 rx data 1
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 14 figure 6 ? transfer of three data words from rt 03 to bc pdin nbgt incmd dtrq iustb h/l gbr eot pdin nbgt incmd dtrq iustb h/l gbr eot figure 7 ? transfer of two data words from bc to rt 03 pdin nbgt incmd dtrq iustb h/l reset eot figure 8 ? mode command reset remote terminal
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 15 figure 10 ? rt to rt transfer of four data words (this rt receiving the data) pdin nbgt incmd dtrq iustb h/l gbr eot figure 9 ? rt to rt transfer of four data words (this rt sending the data) pdin nbgt incmd dtrq iustb h/l gbr eot
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 16 dtak iustb h/l cwc0-cwc4 dtrq subsystem reply time < 13.5s 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 figure 11 ? handshaking for tx data transfers dtak iustb h/l cwc0-cwc4 dtrq subsystem reply time < 1.5s don?t care 250 nsec 250 nsec 500 nsec incremented valid low byte valid high byte valid internal highway figure 12 ? handshaking for rx data transfers
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 17 sa4-sa0 nbgt 1.0s minimum valid valid valid previous command value previous command value previous command value busy latch here tx/rx wc4-wc0 cwc4-cwc0 incmd inclk figure 13 ? new command initialization nbgt incmd vecten h/l enable high byte of vector word onto internal highway enable low byte of vector word onto internal highway figure 14 ? transmit vector word command } 1.5s approx. }
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 18 pdin nbgt incmd sync ilustb eot wc4 h/l 0 0 0 1 1 1 1 1 1 1 0 0 0 0 0 1 0 figure 15 ? synchronize (with data) mode command pdin nbgt incmd sync eot wc0 0 0 0 1 1 1 1 1 1 0 0 0 0 1 0 iustb figure 16 ? synchronize (no data) mode command
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 19 bcopstb ndrg cwen h/l iustb c/d nbgt incmd valc vald statstb dtrg gbr eot rto pdin figure 17 ? bus controller sending command to rt 10001 to transmit two data words
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 20 bcopstb ndrg cwen h/l iustb c/d nbgt incmd valc vald statstb dtrg gbr eot rto pdin figure 18 ? bus controller sending command to rt 10001 to receive two data words
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 21 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
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 22 bcopstb ndrq h/l statstb bcopb pdin bcopa cwen txstb bcopstb h/l bcopb pdin bcopa cwen dwen dwen bcopstb h/l bcopb pdin bcopa statstb rmdstb 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
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 23 pin out description - CT1995 (all versions) pin # function pin # function pin # function 1 nc 31 reqbusb 61 error 2 cwc0 (lsb) 32 reqbusa 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 37 ih 08 (lsb) 67 rx data 1 8cwc238 ih1968rx data 1 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 26 bcopa 56 rx data 0 86 wc0 (lsb) 27 bcopstb 57 rx data 0 87 sserr 28 bcopb 58 bcsten 1 88 wc2 29 pasmon 59 rto 89 wc1 30 ndrq 60 6 mck 90 nc
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 24 ceramic cofired 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
aeroflex circuit technology scdCT1995 rev a 11/21/01 plainview ny (516) 694-6700 25 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 1.6" x 2.4" ceramic plug in CT1995-20-3 1 200 s 1.6" x 2.4" ceramic plug in note: 1. ttl and cmos rt address thresholds. refer to recommended dc operating conditions, page 2. circuit technology aeroflex circuit technology 35 south service road plainview new york 11803 telephone: (516) 694-6700 fax: (516) 694-6715 toll free inquiries: (800) 843-1553 specifications subject to change without notice www.aeroflex.com e-mail: sales-act@aeroflex.com

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