CT2500
MIL-STD-1397 Type D & E Low Level Serial
Interface Protocol Chip
Features
• Performs Source and Sink functions
• Implements Type D & E protocols
• Burst Mode Capability
A E
RO
CIRCUIT TECHNOLOGY
www.aeroflex.com
• Built in System Integrity Features
• Double Buffered Communications
• Low power CMOS
• Available in a PGA Package
• Operates over full Military temperature range -55°C to +125°C
F
LE
X
LA
C
ISO
9001
E
RT
I
F
I
E
D
B
S
I
NC
.
General Description
The CT2500 provides a complete interface between the MIL-STD-1397 transceiver chip set (CT1698) and
most microprocessor based systems. The unit is monolithic and fabricated in CMOS technology, thereby
having very low power requirements. The unit handles all protocols of Type D & E interfaces including Burst
Mode Data and forced EF functions. Screened per individual test methods of MIL-STD-883. Aeroflex Circuit
Technology is an 80,000ft
2
MIL-PRF-38534 certified facility in Plainview, N.Y.
BIT4IN
CMDIN DTAIN CFRMSYNC
RSTERR
Received SOS/SIS
RXDATA
RXCLOCK
Serial
Input
Received Data Shift Register
Check
Logic
32 BIT BIDIRECTIONAL
PARALLEL DATA BUS
D0 - D31
CLK
SO/SI
PAREN
POE
BURST
FIFOEN
D/E
POR
TEST
Received Data Latch
RCVDATA
RCVCNTRL
ERR1
ERR2
OVRFLOW
SYNCIN
WIIN
PRTYIN
STR1
XMIT Data Latch
I/O
Contrl
STR2
FIFORD
RDYFORDTA
G20MHZ
TXDMXD
TXCMXD
ENV
Mode
Control
Logic
XMIT Data Shift Register
Serial
Output
SOS/SIS
for XMIT
WIOUT LDCNTRL BIT4OUT CMDOUT DTAOUT TXSELECT
Figure 1 – Block Diagram
eroflex Circuit T
echnology
– Data Bus Modules For The Future © SCDCT2500 REV A 6/12/98
I/O CONTROL
The CT2500 is very flexible in it’s I/O architecture.
The unit can handle 16 bit and 32 bit data and
command word loading. In addition, data words can
be preloaded into an external FIFO and the unit will
load data words from the FIFO directly without
subsystem intervention. Similarly, data can be
received and automatically loaded into a FIFO. This
frees up the subsystem until the data transfer is
complete. These options are desirable especially
when operating under burst mode transmissions.
Control frames are sent by strobing LDCNTRL and
data is sent by strobing STR2.
SOURCE AND SINK MODES
Both Source and Sink Mode operations are
available in the CT2500. Selection of modes is
accomplished through the Source/Sink pin. In the
Source Mode, the unit will transmit control frames,
32 bit command and data words including burst
mode data. It will receive control frames only. In Sink
Mode, the unit will transmit control frames only and
receive control frames, 32 bit command and data
words, and burst mode data.
SYSTEM INTEGRITY FEATURES
The CT2500 has built in system integrity features.
The unit can generate and send parity with all 32 bit
transmissions. For reception of 32 bit words, the unit
can check for parity, frame, overrun, sync, and bit
count errors.
DATA TRANSFERS
The CT2500 is built to send and receive Type D
and E Control frames. It can transmit and receive
32-bit command and data word. All 32-bit
communications are double buffered for maximum
flexibility. This allows the subsystem to respond with
less critical timing constraints. Burst mode data
transmission can be initiated by setting the "Burst
Mode" pin high. Automatic FIFO operation is
enabled by setting "FIFOEN" pin high. The serial
data out is automatically formatted for the CT1698 to
send out along the cable.
ELECTRICAL CHARACTERISTICS
(V
DD
= 5V ±10%, T
C
= -55 °C to +125°C, unless otherwise specified)
SYMBOL
PARAMETER
LIMIT
I
DD
P
DS
Iin
Ioz
V
IH
V
IL
V
OH
V
OL
Quiescent current
Power Dissipation
Input leakage
Tri-state leakage
Input high level
Input low level
Output high level
Output low level
100uA max
200mW max
10uA max
10uA max
2.0V min
0.8V max
2.4V min @ I
OH
= -4mA
0.4V max @ I
OL
= 4mA
Aeroflex Circuit Technology
2
SCDCT2500 REV A 6/12/98 Plainview NY (516) 694-6700
I/O FUNCTION LISTING
NAME
SO/SI
I/O
I
DESCRIPTION
Source / Sink Mode Select
Determines the overall Functioning Mode of the Device.
"1"= Source emulation. This mode enables the chip to send control frames, single
command and data words and burst data. It is able to receive control frames.
"0" = Sink emulation. In this mode, the chip can only send control frames. It can
receive control frames, command words, single data words and burst data.
Parallel Bi-directional Data Bus (Internal Pullups)
Source Mode:
Input to 32 bit transmit data latch
Sink Mode:
Tri-state output from 32 bit received data latch
Type D / Type E Control Frame Length Select (Internal Pulldown)
"1" = Three bit control frames are transmitted and the received control frame is
checked for a proper three bit length.
"0" = Four bit control frames are transmitted and the received control frame is checked
for a proper four bit length.
Parity Enable (Internal Pullup)
"1" = Parity bit is generated in Source mode and checked for in Sink mode.
"0" = No parity is generated or checked for.
Parity Odd or Even Select (Internal Pullup)
"1" = Odd parity
"0" = Even parity
System Clock
20 megahertz with 50% duty cycle
Burst Mode Select
"1" = Data transmission and Reception can be done in Burst mode
"0" = Normal operation
Source Mode:
Data words loaded during the transmission of another will be
concatenated to the transmission without addition of SYNC or WI bits. The first word
will have a SYNC bit of "1" and and a WI bit, which must be set to "0". The Burst line
must remain stable for the entire duration of the loading and transmission of the data.
Sink Mode:
During a Burst data reception, after the SYNC and WI bits, data words are
picked off at bit count multiples of 32, or 33 with parity enabled, and loaded into the
output latch. The transmission is considered ended when a gap is detected. The line
must be stable during the entire reception.
Strobe One Bar and Strobe Two Bar
Control Strobes for Reading and Writing the Parallel I/O data Latches
Source Mode:
STR1 loads data present on DO-D15 into the lower 16 bit input latch
and STR2 loads data on D16-D31 into the upper 16 bit input latch. Upon completion of
STR2, a sequence is initiated to load the entire 32 bits into a shift register and start a
transmission. The lower 16 bits must be loaded prior to or during the load of the upper
16 bits. For a 32 bit load, STR1 and STR2 can be tied together.
Sink Mode:
STR1 enables the lower 16 bits of a received word to be output on
D0-D15. STR2 enables the upper 16 bits of a received word to be output on D16-D31.
The entire 32 bits of data must be read before another data reception or it will be
overwritten. If this occurs, the overflow flag, OVRFLOW, will go high. The data is
considered completely read upon the completion of STR2.
Command In
Third bit of the Received Control Frame. Valid during RCVCNTRL.
Data In
Second bit of the Received Control Frame. Valid during RCVCNTRL.
DO-D31
I/O
D/E
I
PAREN
I
POE
I
CLK
BURST
I
I
STR1 and
STR2
I
CMDIN
DTAIN
O
O
Aeroflex Circuit Technology
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SCDCT2500 REV A 6/12/98 Plainview NY (516) 694-6700
I/O FUNCTION LISTING (Continued)
NAME
RCVCNTRL
RCVDTA
ERR1, ERR2
I/O
O
O
O
DESCRIPTION
Received Control Bar
Pulses low upon reception of a Control Frame in both Sink and Source modes.
Received Data/Command Word Bar
Pulses low upon reception of a Data or Command word
Error Bit One and Error Bit Two
ERR1
ERR2
0
1
0
1
0
0
1
1
No Error
Bit Count Error in Received Data/Command word or Control Frame
Parity Error in Received Data
Sync Error in Received Data/Command word or Control Frame
OVRFLOW
RSTERR
POR
O
I
I
Overflow Error
"1" = Overflow occurred in the Received Data Latch. Data not read in time.
Reset Error Flags Bar (Internal Pullup)
A low pulse on this line resets the ERR1, ERR2 and OVRFLOW error flags.
Power on Reset Bar
A Master reset. A low pulse on this line resets the internal sequences and error flags.
It does not reset the I/O Data latches.
Word Identifier Bit Out
The value on this line is latched during STR2 for the WI bit position in the word to be
transmitted. A "0" indicates a Data word and a "1" indicates a Command/Interrupt
word.
Word Identifier Bit In
The WI bit of the received word is present on this line during RCVDTA and indicates
whether the word is a Data word or a Command/Interrupt word. The value is latched at
the first RCVDTA for an entire Burst Mode reception.
Command Out
Third bit of the transmitted Control Frame.
Data Out
Second bit of the transmitted Control Frame.
Load Control Frame Bar
This loads the status of CMDOUT, DTAOUT and BIT4OUT into the Control Frame to
be transmitted. Transmission will commence when the loading is completed. This
applies to both Sink and Source modes.
FIFO Enable
Source Mode:
When FIFOEN is held high ("1"), FIFORD’s (FIFO Read Bars) will be
generated when the input data latch is empty (RDYFORDTA = 1). During the FIFORD,
data presented to the parallel bus will be loaded into the input data latch and
transmitted when ready. In a non-burst (single word) condition, FIFOEN must be
removed before RDYFORDTA comes back. A positive pulse of 100 ns duration
satisfies this requirement.
Sink Mode:
The parallel data bus goes active during RCVDTA and will hold for
approximately 25 ns after its rising edge. With a FIFO directly connected to the data
bus, RCVDTA can be used to load all received words into the FIFO. Gating RCVDTA
with WIIN selects only the data words for loading.
WIOUT
I
WIIN
O
CMDOUT
DTAOUT
LDCNTRL
I
I
I
FIFOEN
I
Aeroflex Circuit Technology
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SCDCT2500 REV A 6/12/98 Plainview NY (516) 694-6700
I/O FUNCTION LISTING (Continued)
NAME
FIFORD
I/O
O
DESCRIPTION
FIFO Read Bar
When the device is configured as a Source, this output pulses low during FIFOEN
mode enabling data from a FIFO to be loaded into the input data latch for
transmission.
Ready For Data
This signal is high when the input data latch is available for new data to be loaded in.
When the data is loaded, RDYFORDTA goes low until the word is dumped into the
output shift register.
Envelope
This output envelopes the serial output data by being high during transmission.
Transmit Data / Manchester Data
Serial NRZ data out or Manchester Data out depending on the TXSELECT mode.
Transmit Clock / Manchester Data Bar
Output shift clock or Manchester Data Bar depending on the TXSELECT mode.
Gated 20 Mhz
A gated 20 Mhz clock used in conjunction with Transmit Data, Transmit Clock and
Envelope to generate Manchester data using other Aeroflex encoders such as the
CT1698.
Transmit Mode Select. (Internal Pulldown)
"1" = Serial output format is Manchester Data and Data Bar.
"0" = Output will be NRZ Data and Shift Clock.
Received Data
Received serial NRZ Data in.
Received Clock
Received Shift Clock In.
Test Mode Bar (Internal Pullup)
A low on this pin puts the device into an internal wrap-around test mode. Transmit Data
and Transmit Clock are internally connected to Received Data and Received Clock.
The circuit must be in Source mode and only 32 bit data loads and reads are allowed.
In this mode, STR2 loads the full 32 bits for transmission. When this word is wrapped
back, RCVDTA will pulse low indicating reception of a data or command word. STR1
enables the received data latch to be read out. Transmission of control frames can also
be tested in this mode using the regular LDCNTRL and RCVCNTRL signals.
Bit Four In
Fourth bit of received Type E control frame.
Bit Four Out (Internal Pullup)
Fourth bit of Type E control frame to be transmitted.
Sync In
Sync position of the Received Data Latch.
Control Frame Sync In
Sync position of the Received Control Frame Latch
Parity In
Parity bit position of the Received Data Latch.
RDYFORDTA
O
ENV
TXDMXD
TXCMXD
G20MHZ
O
O
O
O
TXSELECT
I
RXDATA
RXCLOCK
TEST
I
I
I
BIT4IN
BIT4OUT
SYNCIN
CFRMSYNC
PRTYIN
O
I
O
O
O
Aeroflex Circuit Technology
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SCDCT2500 REV A 6/12/98 Plainview NY (516) 694-6700
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