UT1553B BCRTMP **

UT1553 Remote Terminal Multi-Protocol 3-16
FEATURES
INTRODUCTION
 Complete MIL-STD-1553 Remote Terminal Interface
 Mode selectable to comply with either MIL-STD-
The UT1553 RTMP (figures 1 and 4) is a monolithic,
CMOS, VLSI integrated circuit that meets all requirements
for a dual-redundant MIL-STD-1553 Remote Terminal
interface. The RTMP’s advanced design supports both MILSTD-1553A and MIL-STD-1553B serial data bus
protocols, including differences in the status word response
time and bit definitions, providing the system designer a
single-chip solution to most Remote Terminal interface
requirements.
1553A or MIL-STD-1553B bus protocol
 Mil-STD-1773 compatible
 Remote terminal operation is certified by ASD/
ENASC (SEAFAC)
 Implements all dual-redundant Remote Terminal mode









codes and operational functions including broadcast
commands
Provides handshake control for quad-redundant
systems
Data pointers permit programmable memory mapping
for 1553 data over the entire 64K host memory space
Provides all handshaking signals for a DMA interface
Stores 1553 command word and time-tag information
with all incoming data for enhanced data management
Three-state address bus, databus, and control signals
simplify DMA operations
Supports end-of-command activity and data bus error
interrupts
Self-test capability
Available as a gate array macrocell
Available in 84-pin pingrid array, 84-lead leadless chip
carrier, or 84-lead flatpack packages
The UT1553 RTMP provides all requisite 1553 protocol and
data handling, 1553 message error checking, DMA
handshake and control signals, and comprehensive self-test
capabilities. The RTMP’s pointer-based, programmable
memory-mapping architecture permits the host to map 1553
message data anywhere in the 64K memory space. This
advanced memory mapping, along with the RTMP’s control
and status functions, minimize the host system’s 1553
interface overhead.
The UT1553 RTMP is a member of UTMC’s complete
family of high-reliability monolithic MIL-STD-1553
interface products.
 Standard Microcircuit Drawing 5962-88645 available
- QML Q compliant
MODE CODE/
SUBADDRESS
TERMINAL
ADDRESS
5
OUT
IN
OUT
CHANNEL
B
IN
OUTPUT MULTIPLEXING AND
SELF-TEST WRAPAROUNDLOGIC
CHANNEL
A
DECODER
COMMAND
RECOGNITION
MEMORY
ADDRESS
CONTROL
16
16
MEMORY
ADDRESS
3
TIME TAG
CONTROL
BASE PTR
STATUS
LAST CMD
DECODER
MUX
ENCODER
5
13
16
CONTROL
AND ERROR
LOGIC
DATA
TRANSFER
LOGIC
TIMER
LOGIC
9
CONTROL
INPUTS
CONTROL
OUTPUTS
CLOCK AND
RESET
LOGIC
16
DATA
MASTER 12MHz
RESET
Figure 1. UT1553 RTMP Functional Block Diagram
RTMP-1
Table of Contents
1.0
FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
2.0
PIN IDENTIFICATION AND DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
3.0
REMOTE TERMINAL ARCHITECTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.1 Internal Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.2 Read/Write Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.3 Time Tag Data Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.4 Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
3.5 Base Pointer Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
3.6 Read Only Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
3.6.1 Operational Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
3.6.2 Last 1553 Command Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
3.7 Write Only Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.0
REMOTE TERMINAL INTERFACE OPERATION . . . . . . . . . . . . . . . . . . . . . .17
4.1 Programming the BPD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.2 RTMP Pointer Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.3 Pointer Block Location Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4.4 RTMP Data Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
4.5 RTMP Interrupt Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
4.6 RTMP Error Detection Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
4.6.1 Terminal Address Parity Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
4.6.2 Framing or Overrun Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
4.6.3 1553 Message Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
4.7 RTMP Self-Test Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
5.0
1553A AND 1553B MODES OF OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . .25
5.1 Status Word Bit Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
5.2 Mode Code Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
5.3 Status Word Response Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
6.0
RTMP SYSTEM INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
6.1Assigning the Terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
6.2Controlling the DMA Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
6.3Interfacing with the RTMP’s Internal Register . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
6.4RTMP Hardware Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
6.4.1 RTMP -- 1553 Transceiver Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
6.4.2 RTMP DMA Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
7.0
MAXIMUM AND RECOMMENDED OPERATING CONDITIONS31
8.0
DC ELECTRICAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
9.0
AC ELECTRICAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
10.0 PACKAGE OUTLINE DRAWINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
RTMP-2
FUNCTIONAL DESCRIPTION
General Description
The RTMP is an interface device linking a MIL-STD-1553
serial data bus and a host microprocessor system (figure 2).
By selecting the correct state of the 1553 protocol select pin
(PRA/B = 1 for 1553A, 0 for 1553B), the system designer
can program the RTMP to comply fully with either MILSTD-1553A or MIL-STD-1553B.
The link between the 1553 data bus and the RTMP is the
shared memory area. All the data the RTMP transmits or
receives over the 1553 bus is stored in this shared memory
area. The RTMP accesses the shared memory with its DMA
signals (DMAR, DMAG, and DMAEN), the 16-bit
bidirectional data bus (D0-D15), and the 16-bit address bus
(A0-A15).
Since the RTMP’s architecture is based on a series of data
pointers, the 1553 transmit and receive data can be placed
anywhere in the 64K memory space, allowing the system
designer to optimize memory usage. The system designer
can program the RTMP to store the data received over the
1553 bus in one of two ways. The RTMP can store the
received data in a single data buffer or in separate buffers.
When the RTMP stores the received data in a single buffer,
all received data, regardless of subaddress, is stored in
contiguous locations in the shared memory. When the
RTMP stores the received data in separate buffers, the
RTMP stores the data associated with each of the 30
subaddresses in unique locations in memory.
The RTMP has six internal registers that provide the host
subsystem with RTMP control and status information.
Three of these registers are read/write: Time Tag Data
Register (TTD), the Control Register (CTL), and the Base
Pointer Data Register (BPD). Two are read only:
Operational Status Register (OPS), and the Last Command
Register (LCM). The Stop Self-Test Register (SST) is a
write-only register. To control the RTMP and the 1553
interface, the host begins by programming the Base Pointer
Data Register. By programming the BPD, the system
designer tells the RTMP where in the shared memory the
64-word Pointer Block will reside, whether the RTMP will
store the 1553 received data in single or separate buffers,
and how deep these data buffers will actually be. Figure 3
is a simple representation of the RTMP’s memory-mapping
architecture.
After the host has programmed the BPD, the 1553 interface
is enabled by setting either CHAEN or CHBEN in the
RTMP’s Control Register. The RTMP now monitors the
1553 data bus for a valid command word or mode code to
its particular terminal address. When received, the RTMP
looks at the mode bit (single/separate) in the BPD, the 1553
command transmit/receive bit, and the mode code or
subaddress portion of the 1553 command to determine
which of the address pointers in the 64-word Pointer Block
the RTMP will use for this particular memory transaction.
Each memory transaction consists of memory writes for
receive command words and memory reads for transmit
command words. This process continues until all 1553 data
words have been received or transmitted. If the host has
enabled any of the RTMP’s interrupts, the RTMP asserts
them when the memory transaction is complete.
RTMP-3
64K x 16
SHARED RAM
ADDRESS BUS
HOST
DATA BUS
UT1553 RTMP
SUBSYSTEM
CONTROL
UT63M125
1553 TRANSCEIVER
1553 BUS A
1553 BUS B
Figure 2. RTMP General System Diagram
64K x 16
SHARED RAM
THESE TEN BITS FORM THE ADDRESS
OF THE STARTING LOCATION OF THE
64-WORD POINTER BLOCK.
MSB
B
P
A
6
B
U
F
S
L
LSB
B BB B
S SSS
I I I I
Z ZZZ
3 210
0000H
64-WORD
POINTER BLOCK
RECEIVE DATA
POINTER (30)
TRANSMIT DATA
POINTER (30)
BASE POINTER
DATA REGISTER
BUFFER MODE SELECT
THE RECEIVE DATA BUFFER SIZE
IS PROGRAMMED WITH THESE FOUR BITS.
RECEIVE SUBADDRESS
DATA BUFFER 8 TO 32K WORDS
TRANSMIT SUBADDRESS
DATA BUFFER
FFFFH
Figure 3. RTMP Receiveand Transmit Data Memory Mapping
RTMP-4
2.0 PIN IDENTIFICATION AND DESCRIPTION
BIPHASE
OUT
TAZ
TAO
TBZ
TBO
27
26
31
30
(L8)
(J7)
(K9)
(L10)
BIPHASE
IN
RAZ
RAO
RBZ
RBO
25
23
34
33
(K7)
(L6)
(J10)
(K10)
TERMINAL
ADDRESS
RTA0
RTA1
RTA2
RTA3
RTA4
RTPTY
77
76
75
74
73
71
(B1)
(C2)
(B2)
(A1)
(B3)
(A3)
MCSA0
MCSA1
MCSA2
MCSA3
MCSA4
15
16
17
18
19
(L3)
(K4)
(L4)
(K6)
(K5)
EORT
EOMC
MERR
TIMERON
CHA/B
COMSTR
MC/SA
DMAR
*DMAG
*DMAEN
36
37
39
29
28
38
21
(J11)
(H10)
(G9)
(L9)
(K8)
(H11)
(J5)
47
48
49
(F11)
(D11)
(D10)
RD
WR
*CS
AV
RRD
RWR
**TAPEN
*SVC
**ILLCOM
**SME
**ENBC
PRA/B
**TEST
45
46
44
52
50
51
72
40
22
41
13
12
14
(E11)
(E10)
(E9)
(C10)
(C11)
(B11)
(A2)
(G10)
(J6)
(G11)
(K3)
(K2)
(L2)
MODE CODE/
SUBADDRESS
STATUS
SIGNALS
DMA
SIGNALS
CONTROL
SIGNALS
++
*
**
Bidirectional pin.
Pin internally pulled up.
Pin internally pulled down.
(B4)
(A4)
(A6)
(B5)
(C5)
(C6)
(B6)
(B7)
(C7)
(A8)
(B8)
(A9)
(A10)
(B9)
(B10)
(A11)
70
69
68
67
65
64
63
61
60
59
58
57
56
55
54
53
A 0 ++
A 1 ++
A 2 ++
A3
A4
A5
A6
ADDRESS
A7
A8
LINES
A9
A 10
A 11
A 12
A 13
A 14
A 15
(L1)
(J2)
(K1)
(J1)
(H2)
(H1)
(G3)
(G2)
(G1)
(F1)
(E1)
(E2)
(F2)
(D1)
(D2)
(C1)
11
10
9
8
7
6
5
4
3
2
83
82
81
80
79
78
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D 10
D 11
D 12
D 13
D 14
D 15
DATA
LINES
(L7)
(F9)
(A5)
(E3)
24
43
66
84
VDD
VDD
VDD
VDD
POWER
(F3)
(L5)
(F10)
(A7)
1
20
42
62
VSS
VSS
VSS
VSS
(K11)
35
CLK
CLOCK
(L11)
32
RESET
RESET
GROUND
Leadless chip carrier pinnumbers are not in parentheses.
( ) Pingrid array pin numbers are in parentheses.
Figure 4. RTMP Functional Pin Description
RTMP-5
Legend for TYPE and ACTIVE fields:
TO = TTL output
I = TTL input
TUI = TTL input (pull-up)
TDI = TTL input (pull-down)
TTO = Three-state TTL output
TTB = Three-state TTL bidirectioal
AH =Active high
AL = Active low
DATA BUS
NAME
PIN NUMBER
LCC
PGA
TYPE
ACTIVE
DESCRIPTION
D15
78
C1
TTB
--
Bit 15 (MSB) of the bidirectional Data bus.
D14
79
D2
TTB
--
Bit 14 of the bidirectional Data bus.
D13
80
D1
TTB
--
Bit 13 of the bidirectional Data bus.
D12
81
F2
TTB
--
Bit 12 of the bidirectional Data bus.
D11
82
E2
TTB
--
Bit 11 of the bidirectional Data bus.
D10
83
E1
TTB
--
Bit 10 of the bidirectionalData bus.
D9
2
F1
TTB
--
Bit 9 of the bidirectional Data bus.
D8
3
G1
TTB
--
Bit 8 of the bidirectional Data bus.
D7
4
G2
TTB
--
Bit 7 of the bidirectional Data bus.
D6
5
G3
TTB
--
Bit 6 of the bidirectional Data bus.
D5
6
H1
TTB
--
Bit 5 of the bidirectional Data bus.
D4
7
H2
TTB
--
Bit 4 of the bidirectional Data bus.
D3
8
J1
TTB
--
Bit 3 of the bidirectional Data bus.
D2
9
K1
TTB
--
Bit 2 of the bidirectional Data bus.
D1
10
J2
TTB
--
Bit 1 of the bidirectional Data bus.
D0
11
L1
TTB
--
Bit 0 (LSB) of the bidirectional Data bus.
RTMP-6
ADDRESS BUS
NAME
PIN NUMBER
TYPE
ACTIVE
A11
TTO
--
Bit 15 (MSB) of the Address bus.
54
B10
TTO
--
Bit 14 of the Address bus.
A13
55
B9
TTO
--
Bit 13 of the Address bus.
A12
56
A10
TTO
--
Bit 12 of the Address bus.
A11
57
A9
TTO
--
Bit 11 of the Address bus.
A10
58
B8
TTO
--
Bit 10 of the Address bus.
A9
59
A8
TTO
--
Bit 9 of the Address bus.
A8
60
C7
TTO
--
Bit 8 of the Address bus.
A7
61
B7
TTO
--
Bit 7 of the Address bus.
A6
63
B6
TTO
--
Bit 6 of the Address bus.
A5
64
C6
TTO
--
Bit 5 of the Address bus.
A4
65
C5
TTO
--
Bit 4 of the Address bus.
A3
67
B5
TTO
--
Bit 3 of the Address bus.
A2
68
A6
TTB
--
Bit 2 of the Address bus. Address bits A2 - A0 are
bidirectional so the host can select one of the RTMP’s internal
registers during internal I/O operations.
A1
69
A4
TTB
--
Bit 1 of the Address Bus. (Reference A2)
A0
70
B4
TTB
--
Bit 0 (LSB) of the Address Bus. (Reference A2)
LCC
PGA
A15
53
A14
DESCRIPTION
DMA SIGNALS
NAME
PIN NUMBER
LCC
PGA
DMAR
47
F11
TO
AL
DMA Request. Indicates the RTMP is requesting
use of the Data bus from the current bus master.
DMAG
48
D11
TUI
AL
DMA Grant. Gives control of the Data bus to the RTMP.
DMAG is recognized only if DMAEN is high. DMAG must
remain asserted until AV goes high to ensure that the RTMP
completes the current DMA cycle.
DMAEN
49
D10
TUI
AH
DMA Enable. When high, this input allows the
RTMP to recognize DMAG. When low, DMAEN places all
three-state pins in a high-impedance state and disables the
RTMP’s memory access cycle.
TYPE ACTIVE
DESCRIPTION
RTMP-7
CONTROL SIGNALS
NAME
PIN NUMBER
TYPE ACTIVE
LCC
PGA
CS
44
E9
RD
45
WR
DESCRIPTION
TUI
AL
Chip Select. This input, along with RD and WR, allows
the host to access the RTMP’s internal data registers.
E11
TI
AL
Read. When used in conjunction with CS, RD allows the
RTMP to place data from the selected internal register on the
Data bus (D15-D0).
46
E10
TI
AL
Write. When used in conjunction with CS, WR latches data
from the Data bus (D15-D0) into the selected RTMP internal
register.
AV
52
C10
TTO
AL
Address Valid. The RTMP asserts AV to indicate that the
address (A15-A0) is valid.
RRD
50
C11
TTO
AL
RAM Read. The RTMP asserts RRD during DMA cycles
that require data from system RAM.
RWR
51
B11
TTO
AL
RAM Write. The RTMP asserts RWR during DMA cycles
to write data to system memory.
SVC
40
G10
TUI
AL
Superseding Valid Command. The host system uses this
input when more than one RT is present in the system; i.e.,
a quad-redundant system. When asserted, this input causes
the RTMP to terminate all present activity and perform an
internal reset of encoders/decoders, RT state machine, and
DMA state machine. Registers are not affected. Do not assert
while DMAR is asserted (tpw 250ns minimum).
SME
41
G11
TDI
AH
Set Message Error. Asserting this input causes the
Message Error bit in thestatus word to be set.
ILLCOM
22
J6
TDI
AH
Illegal Command. This input illegalizes a command
word that the RTMP accepts but the system does not
support. When set, the RTMP responds with the
Message Error bit set in the status word. ILLCOM
is used in conjunction with the Mode Code/
Subaddress outputs.
PRA/B
12
K2
TI
--
Program A/B. This input is the 1553 mode select input. A high
input places the RTMP in the MIL-STD-1553A mode; a low
places the RTMP in the MIL-STD-1553B mode.
ENBC
13
K3
TDI
AH
Enable Broadcast. A high on this input, when the
RTMP is in the 1553B mode, allows the RTMP to
recognize a broadcast command word.
TEST
14
L2
TDI
AH
Test. The TEST input pin allows the user to select between
internal (TEST = 0) or external (TEST = 1) self-test. When
TEST equals a logic one and DMAEN equals a logic zero,
MCSA (4:0) and MC/SA three-state.
RTMP-8
STATUS SIGNALS
NAME
PIN NUMBER
LCC
PGA
TYPE
ACTIVE
DESCRIPTION
EORT
36
J11
TTO
AL
End of Receive/Transmit. This interrupt is a pulse that is
maskable by writing to the Control Register. The user can
select EORT to occur at the end of receive command activity,
at the end of transmit command activity, under either of these
conditions, or disable it completely. The EORT output is designed to simulate an open-collector output and requires a
pull-up resistor. (250ns pulse width). This signal is not generated if a message error condition exists.
EOMC
37
H10
TTO
AL
End of Mode Code. this non-maskable interrupt is a pulse that
occurs at the end of all memory accesses associated with any
mode code command. The EOMC output is designed to simulate an open-collector output and requires a pull-up resistor.
EOMC and EORT can be logically ORed together to form a
composite interrupt. The 250ns pulse width is generated after
command word is stored. This signal is not generated if a
message error condition exists.
COMSTR
38
H11
TO
AL
Command Strobe. This low-going pulse identifies receipt of a valid 1553 command word.
MERR
39
G9
TO
AH
Message Error. Active when the RTMP detects an error in
the 1553 transmission and sets the Message Error bit in the
status word. MERR is reset when the RTMP receives the next
valid command word. (COMSTR assertion)
CHA/B
28
K8
TO
--
Channel A/B. When high, this output indicates the RTMP
received the last command on Channel A; when low, the last
command was received on Channel B.
TIMERON
29
L9
TO
AL
Timer On. Indicates the RTMP is transmitting data.
The output remains active until the data transmission is
complete or the internal fail-safe timer times out (600ms
for 1553A and 800ms for 1553B). The RTMP internally
disables both transmitters and keeps them disabled until the
RTMP receives a valid command word. This signal is asserted approximately 250ns
before beginning of status word transmission.
MODE CODE/SUBADDRESS
NAME
MC/SA
MCSA0
MCSA1
MCSA2
MCSA3
MCSA4
PIN NUMBER
LCC
PGA
21
J5
15
16
17
18
19
L3
K4
L4
K6
K5
TYPE
ACTIVE
DESCRIPTION
TTO
AL
Mode Code/Subaddress. MC/SA = 0 indicates that the MCSAO-MCSA4 pins contain the Mode Code bits of the most
recently received mode code. MC/SA = 1 indicates that
MCSA0-MCSA4 pins contain the Subaddress bits of the
most recently received command word.
TTO
--
Mode Code/Subaddress. These five bits are used in conjunction with the MC/SA output. MC/SA = 0 indicates that these
five bits are the five least significant bits of the mode code
command word. MC/SA = 1 indicates these five bits are the
1553 command word subaddress.
RTMP-9
REMOTE TERMINAL ADDRESS
NAME
PIN NUMBER
TYPE ACTIVE
LCC
PGA
RTA4
RTA3
RTA2
RTA1
RTA0
73
74
75
76
77
B3
A1
B2
C2
B1
TI
TAPEN
72
A2
TDI
RTPTY
71
A3
TI
--
AH
--
DESCRIPTION
Remote Terminal Address Inputs. The RTMP uses
these inputs to select the terminal address for this
specific remote terminal.
Terminal Address Parity Enable. Enables the
RTMP’s Terminal Address parity-checking
function.
Remote Terminal Parity. When the Terminal
Address parity-checking function is enabled
(TAPEN = 1), RTPTY must provide odd parity
for the terminal address input pins (RTA4-RTA0).
MASTER RESET AND CLOCK
NAME
PIN NUMBER
TYPE ACTIVE
LCC
PGA
DESCRIPTION
RESET
32
L11
TI
AL
Reset. Initializes all internal functions of the RTMP.
RESET must be asserted before normal RTMP operation.
CLK
35
K11
TI
--
Clock. The clock input requires a 50% 10% duty cycle
with an accuracy of 12MHz 0.01%.
CHANNEL A BIPHASE SIGNALS
NAME
PIN NUMBER
TYPE ACTIVE
LCC
PGA
DESCRIPTION
RAO
23
L6
TI
--
Receiver (Channel) A One. Manchester input from
the 1553 bus receiver.
RAZ
25
K7
TI
--
Receiver (Channel) A Zero. This input is the
complement of RAO.
TAO
26
J7
TO
--
Transmitter (Channel) A One. This Manchesterencoded data output is connected to the 1553 bus
transmitter input. The output is idle low.
TAZ
27
L8
TO
--
Transmitter (Channel) A Zero. This output is
the complement of TAO. The output is idle low.
RTMP-10
CHANNEL B BIPHASE SIGNALS
NAME
PIN NUMBER
LCC
PGA
TYPE ACTIVE
DESCRIPTION
RBO
33
K10
TI
--
Receiver (Channel) B One. Manchester data input
from the 1553 bus receiver.
RBZ
34
J10
TI
--
Receiver (Channel) B Zero. This input is the
complement of RBO.
TBO
30
L10
TO
--
Transmitter (Channel) B One. This Manchesterencoded output is connected to the 1553 bus
transmitter input. The output is idle low.
TBZ
31
K9
TO
--
Transmitter (Channel) B Zero. This output is the
complement of TBO. The output isidle low.
POWER AND GROUND
NAME
PIN NUMBER
LCC
PGA
TYPE ACTIVE
VDD
24
43
66
84
L7
F9
A5
E3
--
--
VSS
1
20
42
62
F3
L5
F10
A7
--
--
3.0 REMOTE TERMINAL ARCHITECTURE
3.1 Internal Registers
The RTMP has six internal registers that allow the host to
control the RTMP’s actions and also to obtain its operational
status. The host can read from or write to three of these
registers: the Time Tag Data Register (TTD), the Control
Register (CTL), and the Base Pointer Data Register (BPD).
Two of the registers are read-only: the Operational Status
Register (OPS), and the Last Command Register (LCM).
The Stop Self-Test Register (SST) is a write-only register.
Six signals allow the host to access the RTMP’s internal
registers. Three of the six signals are control signals: Chip
Select (CS), Read (RD), and Write (WR). The other three
signals are the RTMP’s bidirectional address lines, A0 - A2.
When the CS = 0, the three least significant address lines,
A0 - A2, become inputs to the RTMP. The RTMP decodes
these three address lines, along with CS, RD, and WR, to
determine which of the six internal registers the host is
attempting to access. Table 1 shows the addresses for the
RTMP’s internal registers for read and write operations.
DESCRIPTION
+5 VDC Power. Power supply input must be
Reference Ground. Zero VDC logic ground.
3.2 Read/Write Registers
The RTMP has three internal read/write registers. These
three registers are:
 The Time Tag Data Register
 The Control Register
 The Base Pointer Data Register
Time Tag Data Register (TTD)
The TTD contains a free-running, 16-bit, ripple counter.
The Time Tag clock has a resolution of 64ms. The TTD is
initialized to 0000H when the host asserts the RESET input.
All TTD bits are programmable by performing a write to
the TTD with the desired bit pattern.
The RTMP stores the TTD’s value in the shared memory
area at the end of each 1553 receive message. The host can
also directly read the TTD. Since the TTD is a free-running
counter, the host may read the TTD while the counter is
rippling, resulting in the host reading erroneous data. If this
situation presents a problem, the host should read the TTD
data twice. Figure 5 represents the TTD. (0000H after
Master Reset.)
RTMP-11
Table 1. RTMP Internal Register Addresses
1. RTMP Register Write Addresses
CS
WR
0
0
0
0
0
A2
A1
A0
0
0
0
0
1
0
0
1
1
X
0
1
0
1
X
A2
A1
A0
0
0
0
0
0
Time Tag Data Register
Control Register
Base Pointer Data Register
Stop Self-Test Register
Don’t Care
2. RTMP Register Read Addresses
CS
RD
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
1
0
0
1
0
1
0
0
0
0
0
0
0
1
1
1
0
1
1
1
0
1
Time Tag Data Register
Control Register
Base Pointer Data Register
Operational Status Register
Last 1553 Command Register
Don’t Care
Don’t Care
Don’t Care
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
1
1
1
1
1
1
9
8
7
6
5
4
3
2
1
0
5
4
3
2
1
0
MSB
RTMP-12
Figure 5. The Time Tag Data Register
LSB
3.4 Control Register (CTL)
The CTL provides the host with the ability to control four functions: (1) programming the bits in 1553 status word; (2) masking
the End of Receive/Transmit message activity interrupt (output pin EORT); (3) enabling and selecting the channel for the selftest; and (4) selecting the active 1553 channel. The definition of the 1553 status word bits in the CTL is different when the
RTMP is operating in the 1553A mode (PRA/B = 1) as opposed to the1553B mode (PRA/B = 0). Figure 6 shows the bit
definitions in the CTL for the 1553A mode; figure 7 shows the definition for the 1553B mode.
The host determines the CTL functions status by reading the CTL Register.
CTL Bit Definitions - 1553A Mode
Bit 15
CHAEN [0]
Channel A Enable. When CHAEN = 1, the RTMP responds to a 1553 command word or mode
code on bus Channel A. CHAEN = 0 disables the RTMP from responding to 1553 command word
or mode code on 1553 bus Channel A.
Bit 14
CHBEN [0]
Channel B Enable. When CHBEN = 1, the RTMP responds to a 1553 command word or mode
code on bus Channel B. CHBEN = 0 disables the RTMP from responding to 1553 command word
or mode code on 1553 bus Channel B. Disable for internal self-test.
Bit 13
STEN [0]
Self-Test Enable. STEN enables the RTMP’s internal self-test.
Bit 12
STCS [0]
Self-Test Channel Select. If the host has enabled an RTMP self-test (STEN = 1), STCS selects
the RTMP receiver channel to test. STCS = 1 selects Channel A, and STCS = 0 selects Channel B.
Bit 11
IM1 [0]
Interrupt Mask One. If IM1 = 1, the EORT interrupt output is active at the end of 1553 receive
command memory activity. IM1 = 0 masks this interrupt function.
Bit 10
IM2 [0]
Interrupt Mask Two. If IM2 = 1, the EORT interrupt output is active at the end of 1553 transmit
command memory activity. IM2 = 0 masks this interrupt function.
Bit 9
SWB10 [0]
Status Word Bit 10. When the host sets this bit, SWB10 = 1, the bit in the RTMP’s status word
that is transmitted during bit time ten is set (see figure 30 for status word bit time definitions).
The bits in the status word are system-defined in MIL-STD-1553A.
Bit 8
SWB11 [0]
Status Word Bit 11. When the host sets this bit (SWB11 = 1), the bit in the RTMP’s status word
transmitted during bit time 11 is set.
Bit 7
SWB12 [0]
Status Word Bit 12. When the host sets this bit (SWB12 = 1), the bit in the RTMP’s status word
transmitted during bit time 12 is set.
Bit 6
SWB13 [0]
Status Word Bit 13. When the host sets this bit (SWB13 = 1), the bit in the RTMP’s status word
transmitted during bit time 13 is set.
Bit 5
SWB14 [0]
Status Word Bit 14. When the host sets this bit (SWB14 = 1), the bit in the RTMP’s status word
transmitted during bit time 14 is set.
Bit 4
SWB15 [0]
Status Word Bit 15. When the host sets this bit (SWB15 = 1), the bit in the RTMP’s status word
transmitted during bit time 15 is set.
Bit 3
SWB16 [0]
Status Word Bit 16. When the host sets this bit (SWB16 = 1), the bit in the RTMP’s status word
transmitted during bit time 16 is set.
Bit 2
SWB17 [0]
Status Word Bit 17. When the host sets this bit (SWB17 = 1), the bit in the RTMP’s status word
transmitted during bit time 17 is set.
Bit 1
SWB8 [0]
Status Word Bit 18. When the host sets this bit (SWB18 = 1), the bit in the RTMP’s status word
transmitted during bit time 18 is set.
Bit 0
TFLG
Terminal Flag. TFLG = 1 sets the Terminal Flag bit in the 1553A status word. TFLG = 0 resets
the Terminal Flag bit in the 1553A status word.
RTMP-13
CTL Bit Definitions - 1553B Mode
Bit 15
CHAEN [0]
Bit 14
CHBEN [0]
Channel B Enable. Same as 1533A mode. Disable for internal self-test.
Bit 13
STEN [0]
Self-Test Enable. Same as 1553A mode.
Bit 12
STCS [0]
Self-Test Channel Select. Same as 1553A mode.
Bit 11
IM1 [0]
Interrupt Mask One. Same as 1553A mode.
Bit 10
IM2 [0]
Interrupt Mask Two. Same as 1553A mode.
Bit 9
INSTR [0]
Instrumentation Bit. When INSTR = 1, the RTMP’s 1553 status word response has the Instrumentation bit set. This bit remains set until INSTR is set to 0.
Bit 8
SVREQ [0]
Service Request Bit. When SVREQ = 1, the RTMP’s 1553 status word response has the Service
Request bit set. This bit remains set until SVREQ is set to 0.
Bit 7
N/A
This bit is defined as a reserved bit in MIL-STD-1553B and is not used. Setting this bit has no
effect on the status word response.
Bit 6
N/A
Same as bit 7.
Bit 5
N/A
Same as bit 7.
Bit 4
BDCST [0]
Broadcast Bit. When BDCST = 1, the RTMP’s 1553 status word response has the Broadcast bit
set. Manual override; not cleared by receipt of next command. Broadcast bit in outgoing status
word is set to a logical one on the receipt of broadcast command.
Bit 3
BUSY [0]
Busy Bit. When BUSY = 1, the RTMP’s 1553 status word response has the Busy bit set. This bit
remains set until is set to 0.
Bit 2
SFLG [0]
Subsystem Flag. When SFLG = 1, the RTMP’s 1553 status word response has the Subsystem Flag
bit set. This bit remains set until SFLG is set to 0.
Bit 1
N/A
Same as bit 7.
Bit 0
TFLG [0]
Terminal Flag. Same as 1553A mode.
15
C
H
A
E
N
14
C
H
B
E
N
13 12
S S
T T
E C
N S
11
I
M
1
10
I
M
2
9
S
W
B
1
0
Channel A Enable. Same as 1553A mode. Disable for internal self-test.
8
S
W
B
1
1
7
S
W
B
1
2
6
S
W
B
1
3
5
S
W
B
1
4
4
S
W
B
1
5
3
S
W
B
1
6
2
S
W
B
1
7
MSB
Figure 6. The Control Register in 1553A Mode
RTMP-14
1
S
W
B
1
8
0
T
F
L
G
LSB
15
C
H
A
E
N
14
C
H
B
E
N
13 12
S S
T T
E C
N S
11
I
M
1
10
I
M
2
9
I
N
S
T
R
8 7 6 5
S N N N
V / / /
R A A A
E
Q
4
B
D
C
S
T
3
B
U
S
Y
2
S
F
L
G
MSB
Figure 7. The Control Register in 1553B Mode
1
N
/
A
0
T
F
L
G
LSB
3.5 Base Pointer Data Register
The BPD provides three types of information: (1) the location in memory for the 64-word Pointer Block; (2) the receive-data
storage-buffer select for either single or separate data buffers; and (3) the size or depth of the single or separate data buffers
(figure 8). (0000H after Master Reset.)
BPD Bit Definitions
Bit 15-
BPA15-BPA 6 Block Pointer Address. These ten bits provide the RTMP with the Bit 6 ten most significant address
lines for the location, within the 64K word addressing range, of the 64-word Pointer Block.
Bit 5
N/A
This bit is not used.
Bit 4
BUFSL
Buffer Select. When BUFSL = 1, the host selects the RTMP’s single buffer mode of storing 1553
receive data. If BUFSL = 0, the host selects the separate buffer mode of storing 1553 receive data.
Bit 3-
BSIZ3-BSIZ0 Buffer Size Select. These four bits select the size of the receive data Bit 0 buffers and can range
from 3 (0011B) to 15 (1111B). The actual size of the data buffer is equal to 2x where X is the
decimal equivalent of BSIZ3-BSIZ0. The size of the data buffers can range from eight (23) words
to 32K (215) words. The variable X is not defined for zero through two.
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
B
B
B
B
B
B
B
B
B
B
N
B
B
B
B
B
P
P
P
P
P
P
P
P
P
P
/
U
S
S
S
S
A
A
A
A
A
A
A
A
A
A
A
F
I
I
I
I
1
1
1
1
1
1
9
8
7
6
S
Z
Z
Z
Z
5
4
3
2
1
0
L
3
2
1
MSB
0
LSB
Figure 8. The Base Pointer Data Register
3.6 Read Only Registers
The RTMP has two internal registers that are read-only. These two registers provide status information on the operation of the
RTMP:
 The Operational Status Register
 The Last 1553 Command Register
RTMP-15
3.6.1 Operational Status Register (OPS)
The OPS provides the host with the operational status of the RTMP while the RTMP is active. Figure 9 shows the information
bits stored in the OPS.
OPS Bit Definitions
Bit 15
MACT [0]
Message Active. MACT = 1 indicates that the RTMP is actively processing a message. The RTMP
clears MACT upon completing the message.
Bit 14
VMPRO [0]
Valid Message Processed. VMPRO = 1 indicates that the RTMP has processed a valid 1553
message. The host clears VMPRO bit when the OPS is read.
Bit 13
ME [0]
Message Error. ME = 1 indicates that a 1553 message error has occurred. The host clears ME
when the OPS is read unless the condition that caused the MERR still persists after the register
read.
Bit 12
PE [X]
Parity Error. PE = 0 indicates that the RTMP has detected an error in the Terminal Address parity.
This bit can only be active when TAPEN = 1.
Bit 11
STACT [0]
Self-Test Active. STACT = 1 indicates that the RTMP is performing a built-in self-test.
Bit 10
BDCEN [X]
Broadcast Enable. BDCEN = 1 indicates that the RTMP will accept a 1553 broadcast command
as a valid command.
Bit 9
TFGEN [1]
Terminal Flag Enable. When the RTMP is in the 1553B mode, TFGEN = indicates that the
Terminal Flag option is set. Mode code 00110 (Inhibit Terminal Flag) will clear this bit.
Bit 8
CHAEN [0]
1553 Channel A Enable. CHAEN = 1 indicates that Channel A is enabled and ready to process
1553 bus messages.
Bit 7
CHBEN [0]
1553 Channel B Enable. CHBEN = 1 indicates that Channel B is enabled and ready to process
1553 bus messages.
Bit 6
MSEL [X]
Mode Select. When MSEL = 1, the RTMP is in the 1553A mode of operation. MSEL = 0 indicates
the RTMP is in the 1553B mode of operation.
Bit 5
MDRCV [0]
Mode Received. MDRCV = 0 indicates that the last valid 1553 command the RTMP received
was a mode command.
Bit 4
XMTAC [0]
Transmitter Active. XMTAC = 1 indicates that the RTMP’s transmitter is transmitting data.
Bit 3
ILCMD [X]
Illegal Command. ILCMD = 1 indicates that the last 1553 command the RTMP received was
illegal. ILCMD is cleared when the host reads the OPS. In 1553A mode, this bit reflects input pin
ILLCOM. In 1553B mode, this bit reflects either input pin ILLCOM or internal hardware. Internal
illegalization is reviewed in table 2.
Bit 2
CHA/B [0]
Channel A or . CHA/B = 1 indicates that the last valid 1553 command word the RTMP received
was on Channel A. CHA/B = 0 indicates that the last valid command word was on Channel B.
Bit 1
VCMD [0]
Valid 1553 Command. VCMD = 1 indicates that the last command word the RTMP received was
valid. VCMD is reset when the host reads the OPS.
Bit 0
OE [0]
Overrun Error (Framing Error). OE = 1 indicates that the RTMP has detected an overrun error.
This bit is reset when the host performs an OPS read unless the error condition persists.
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
M
A
C
C
V
M
P
R
O
M
E
P
E
S
T
A
C
T
B
D
C
E
N
T
F
G
E
N
C
H
A
E
N
C
H
B
E
N
M
S
E
L
M
D
R
C
V
X
M
T
A
C
I
L
C
M
D
C
H
A
/
B
V
C
M
D
0
E
MSB
LSB
Figure 9. The Operational Status Register
RTMP-16
3.6.2 Last 1553 Command Register (LCM)
The RTMP stores the last valid 1553 command word it
received in the LCM. The only exception is if the RTMP is
in the 1553B mode and it receives a Transmit Last
Command Word mode code. Figure 10 shows the
configuration of the LCM. (0410H after Master Reset.)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
T T T T T T S S S S S W W W W W
A A A A A / A A A A A C C C C C
4 3 2 1 0 R 4 3 2 1 0 4 3 2 1 0
MSB
LSB
3.7 Write Only Register
The RTMP has one register that is write only. This register
is the Stop Self-Test Register (SST). The host can terminate
the RTMP’s self-test execution by writing to the SST. When
the host performs a write to the SST, the RTMP terminates
all memory activity. The Self-Test Enable (STEN) bit in the
CTL is also reset, and the Self-Test Active (STACT) bit in
the OPS is reset. When writing to the SST, the 16-bit data
word is a Don’t Care.
4.0 REMOTE TERMINAL INTERFACE
OPERATION
The RTMP’s remote terminal interface is based on a shared
memory concept where the shared memory is the link
between the MIL-STD-1553 data bus and the host
subsystem (figure 11). All 1553 data, whether transmitted
or received, must at one time be stored in this defined
memory area. The RTMP accesses the shared memory area
with a conventional Direct Memory Access (DMA)
interface.
Since the RTMP can access data anywhere within the 64K
memory space, the host has to specify exactly where in
memory the data associated with each valid transmit or
receive command word or mode code is located. The host
specifies the 1553 data area locations by programming the
RTMP’s Base Pointer Data Register (BPD) and by
initializing the 64-word Pointer Block. The BPD tells the
RTMP where in memory the Pointer Block is located. The
Pointer Block in turn specifies the location in memory where
the data associated with each valid command word or mode
code resides.
Therefore, to control the RTMP’s operation, the host first
programs the BPD to provide the RTMP with three essential
pieces of information: (1) the location in memory of the 64word Pointer Block; (2) the type of data buffer -- single or
separate; and (3) the receive data buffer size. The host can
update the Base Pointer Data Register if a new 64-word
Pointer Block needs to be selected, but do not update the
BPD while the RTMP is processing a message transaction.
Figure 8 shows the BPD.
4.1 Programming the BPD
The host programs the ten most significant bits of the BPD
(BPA15 - BPA6) to point to the starting address of the 64word Pointer Block within the RTMP’s 64K address space.
The RTMP generates the least significant six address lines
to determine which of the words within the 64-word Pointer
Block to use for a specific 1553 transmission. The RTMP
does this by detecting the T/R bit and the subaddress bits of
the last 1553 command word (figure 12). Usually the six
least significant address lines, BPA5-BPA0, are part of the
T/R bit and subaddress or mode code bits of the last
command word, respectively. In some cases, BPA5-BPA0
are forced to specific values: (1) when the RTMP stores the
command word on the data buffer; (2) when the single buffer
mode of operation is chosen; and (3) when a mode code is
received.
The Data Buffer Mode bit, BUFSL, is the next bit in the
BPD that the host programs. The state of BUFSL determines
whether the RTMP stores the 1553 receive data in a single
data buffer (BUFSL = 1) or in separate data buffers (BUFSL
= 0).
Finally, the host programs bits BSIZ3-BSIZ0 in the BPD to
tell the RTMP how large to make the separate data buffers.
A formula determines the size of the data buffer(s): take the
decimal equivalent of the binary number represented by
BSIZ3-BSIZ0, where BSIZ3 is the MSB. This number,
represented by X, can range in size from three to fifteen.
The actual size of the data buffers is equal to 2 X . This means
the data buffers can range from 8 to 32K words in length.
In the single buffer mode, bits BSIZ3-BSIZ0 determine the
size of this single buffer. In the separate buffer mode, all
data buffers are the same size. This means the system
designer must program the buffer size so the largest possible
message the RTMP can receive over the 1553 bus fits within
the programmed buffer size.
4.2 RTMP Pointer Block
The RTMP’s Pointer Block is a contiguous block of 64, 16bit words. The RTMP uses this block of data as the actual
address pointer locations for the memory accesses
associated with each 1553 message transaction. Therefore,
the Pointer Block is divided into receive data pointers, of
which one location is for the single buffer mode, transmit
data pointers, a mode code command pointer location, and
a location for the current 1553 command word (figure 13).
The host must initialize the Pointer Block before enabling
the RTMP’s 1553 receivers
RTMP-17
64-WORD
POINTER BLOCK
THESE THREE BLOCKS CAN
RESIDE ANYWHERE IN THE
64K MEMORY SPACE.
64K x 16 SHARED
RAM
RECEIVE DATA
BUFFER(S)
TRANSMIT DATA
BUFFER(S)
ADDRESS BUS
HOST
DATA BUS
UT1553 RTMP
SUBSYSTEM
CONTROL
UT63M125
1553 TRANSCEIVER
1553 BUS A
1553 BUS B
Figure 11. The Memory Link between the RTMP and the Host Subsystem
The host can program the 16-bit pointer addresses that make
up the Pointer Block to point to any memory location in the
RTMP’s 64K memory space. In this respect, the host has
total flexibility to determine where in RAM it stores the
actual transmit, receive, and mode code data. The RTMP’s
data storage flexibility allows the host to buffer 1553 receive
messages and maintain data integrity.
The host can update the pointer data within the Pointer
Block at any time, but the recommended procedure is for
the host not to update the pointer data for 1553 receive
command data while the RTMP is actively processing a
message. To prevent this action, the host can program the
RTMP to generate an end-of-activity interrupt for every
valid 1553 message with associated data words. In addition,
RTMP-18
the host can read the Operational Status Register to
determine if the RTMP is active.
The RTMP uses the present 1553 command word and the
selected mode of operation, single or separate mode, to
determine which pointer within the 64-word Pointer Block
to use as an address pointer for the memory accesses during
1553 message activity. The 1553 command word T/R Bit
and the subaddress bits, or the mode code bits for a mode
command, specify the exact location of the address pointer
in the Pointer Block for transmit, receive, and mode code
command words. If the host has selected the single mode of
operation, the RTMP forces selection of the address pointer
stored in the single mode location for all receive commands.
The RTMP stores the present command word in the first
64-WORD
POINTER
BASE POINTER DATA
REGISTER
B
P
A
6
MSB
B
P
A
15
10 MOST SIGNIFICANT ADDRESS LINES
16
6 LEAST SIGNIFICANT ADDRESSLINES
THE 16-BIT ADDRESSPOINTS
TO A SPECIFIC LOCATION
IN THE 16-BIT WORD POINTER BLOCK
1553 DATA ADDRESS
T/R
BIT SUBADDRESS
THIS DATA IS FROM THE
CURRENT 1553 COMMAND WORD
Figure 12. Constructionof the Block Pointer Address (BPA) Bits
POINTER
BLOCK
LOCATION
(H)
CURRENT 1553 COMMAND
WORD
00
SUBADDRESS 1 POINTER
01
SUBADDRESS 2 POINTER


02
SUBADDRESS 29 POINTER
1D
SUBADDRESS 30 POINTER
1E
SINGLE BUFFER MODE
POINTER
1F
MODE CODE DATA
POINTER
20
SUBADDRESS 1 POINTER
21
SUBADDRESS 2 POINTER


22
SUBADDRESS 29 POINTER
3D
SUBADDRESS 30 POINTER
3E
NOT USED
3F




4.3 Pointer Block Location Definitions
For the following description of the Pointer Block locations,
please refer to figure 13.
Command Word Data - Location 0-0H of the Pointer Block
contains the last valid 1553 command word the RTMP
received. Bit times 4 through 19 (figure 14) of the 1553
command word are stored in bit positions 15 through 0,
respectively. The RTMP updates this location with the most
recent command word except when the RTMP is in the
1553B mode and it receives a Transmit Last Command
mode code.
Separate Mode, Receive Data Pointers - Pointer Block
address locations 1-30 (01H-1EH) contain the pointer
values for each receive command word subaddress if the
RTMP is operating in the separate mode (Bit 4 of the BPD
= 0). The RTMP selects the address pointer data from one
of these locations by using the subaddress of the most recent
receive command word. The RTMP internally stores this
pointer value. This stored pointer value points to the
memory location where the RTMP stores the received data
associated with this subaddress. After the RTMP has stored
all data associated with this subaddress in memory, the
RTMP stores the updated pointer value back into the
selected location in the Pointer Block. The updated pointer
value points to the next available location in memory.
Figure 13. The 64-Word Pointer Block
RTMP-19
Single Mode, Data Pointer - When the host selects the single
mode of operation (bit 4 of the BPD = 1), the pointer value
at location 31 (1FH) of the Pointer Block is the address the
RTMP uses to store all 1553 receive data, regardless of the
command word’s subaddress. After the RTMP has stored
all data associated with a 1553 receive command word, the
RTMP stores an updated pointer value back into location 31
of the Pointer Block. The updated pointer value points to
the next available location in memory.
data word. A mode code with data word is only valid when
the RTMP is operating in the 1553B mode. When the RTMP
is operating in the 1553A mode, it does not recognize or
process any mode code with an associated data word.
Mode Code Pointer - The RTMP uses the pointer value
stored in location 32 (20H) of the Pointer Block when it
recognizes a valid mode code command with an associated
BIT
1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 1 1 1 1 2
TIMES
0 1 2 3 4 5 6 7 8 9 0
COMMAND
WORD
5
1
5
5
1
REMOTE T
SUBWORD P
SYNC TERMINAL / ADDRESS/ COUNT/ A
MODE R
ADDRESS R MODE
CODE
Figure 14. Command WordBit-Time Definitions

1553A mode: No mode codes with data word allowed.

1553A mode: MC/SA field = 00000 or 11111 is a
mode code.

1553B mode: MC/SA field = 00000 or 11111 is a
mode code.
The RTMP stores the pointer value from location 32
internally. The RTMP uses bits 15-4 of this pointer value to
point to a memory location of a data block containing the
data words associated with each mode code. Bits 3-0 of the
pointer address are the four least significant bits of the mode
code the RTMP received. These four bits specify the data
word within this data block that the RTMP uses for this
specific mode code. Figure 15 shows how the RTMP
handles mode codes with associated data words.
Transmit Data Pointers - Pointer Block address locations
33 - 62 (21H-3EH) contain the pointer values for each of
the 1553 transmit command word subaddresses. The RTMP
64-WORD POINTER
BLOCK
TWELVE MSBs
OF THE
STORED ADDRESS
A MODE CODE
WITH DATA WORD
POINTS TO THIS
LOCATION.
MODE CODE
DATA BLOCK
LOCATION
20H
12
4
16
MODE CODE
DATA ADDRESS
DATA WORD FOR
THIS MODE CODE
16
WORD
FOUR LSBs OF
THIS 16-WORD BLOCK
THE MODE CODE
CAN BE LOCATED ANYWHERE
(1)
IN THE 64K MEMORY SPACE.
MODE
COMMAND
TERMINAL T/
ADDRESS
R
SYNC
Note:
0000 Transmit Vector Word
0001 Synchronize with data
0010 Transmit Last Command
00000
MODE
CODE
P
A
R
0011 Transmit BIT Word
0100 Selected Transmitter Shutdown
0101 Override Selected Transmitter Shutdown
Figure 15. Mode Code with Associated Data Word Memory Mapping
RTMP-20
selects the address pointer data from one of these locations
using the subaddress of the most recent valid command
word. The RTMP internally stores this pointer value. This
stored pointer value points to the memory location where
the RTMP accesses the data to transmit with this subaddress.
Every RTMP memory access for transmitted data
increments the pointer value by one until the RTMP has
transmitted all data. Only the host can update the pointer
values stored in the Pointer Block. Therefore, if the host
requires transmit data buffering, the host must control the
pointer values stored in the Pointer Block. No identification
word or time tag is associated with transmit commands.
Note that the RTMP does not use address location 63 (3FH)
of the Pointer Block.
4.4 RTMP Data Storage
The RTMP uses two modes of allocating memory for 1553
receive messages: (1) the single buffer mode, and (2) the
separate buffer mode. The user selects the buffer mode by
programming bit 4 (BUFSL) of the Base Pointer Data (BPD)
Register.
Both modes of operation are based on a ring-buffer type of
memory mapping. Ring-buffer memory mapping means the
RTMP stores all incoming 1553 data words sequentially in
memory starting with an initial address value. The initial
address value is one of the address values stored in the 64word Block Pointer. Note that the initial pointer address
must be set up on a boundary consistent with the chosen
buffer size. Example: If the buffer size is sixteen (0010H),
the initial pointer address must be some multiple of sixteen.
After the RTMP selects an address pointer within the Pointer
Block, it loads the selected address pointer into an internal
up-counter. Every time the RTMP performs a memory store
operation, the up-counter increments by one. Therefore, the
address pointer always points to the next sequential memory
location. The RTMP continues to increment the address
pointer until it reaches the programmed buffer size, which
the user programs with bits 3 through 0 of the BPD (BSIZ3BSIZ0). When the RTMP reaches the programmed buffer
size, the internal up-counter ripples over; i.e., it returns to
all zeros. At this time, the address pointer once again points
to the initial block boundary memory address. To avoid the
possibility of corrupting the initial receive data after the upcounter has rippled over, the user must read the data in the
block before this event occurs. After the RTMP completes
all memory accesses, the RTMP stores the updated address
pointer in its initial 64-word Pointer Block location.
When the user chooses the single buffer mode of operation
(BUFSL = 1), the RTMP always accesses the same address
pointer within the 64-word Pointer Block for every 1553
receive command. Since the RTMP stores all 1553 data
words in the same buffer during this mode of operation, the
user needs to program the buffer size large enough to allow
the RTMP to store several 1553 messages before it
overwrites the data at the beginning of the buffer.
When the user chooses the separate buffer mode of
operation (BUFSL = 0), the RTMP uses the subaddress of
the present 1553 command word to select which of the
address pointers within the 64-word Pointer Block it will
use to store the received data. Therefore, the user can define
up to 30 separate data buffers, one for each receive
subaddress, anywhere in memory. The starting memory
location of each buffer is stored in the receive section of the
Pointer Block. In the separate buffer mode, the user needs
to program the buffer size so it is large enough to keep the
RTMP from overwriting the current data in any of the
separate data buffers if the RTMP receives a new message
with the same subaddress before the host can read the data
from that data buffer.
Figures 16a and 16b show how each mode operates for a
sample receive transmission.
In addition to the data words associated with a receive
command, the RTMP also stores two additional words, an
identification word, which the RTMP stores immediately
before the data words, and a time tag word, which the RTMP
stores immediately after the data words. The identification
word is the 1553 command word associated with the data
in this data block, and the time tag word is the output of the
Time Tag Register. Command word bit time four (figure 14)
is stored as the MSB of the identification word and
command word bit time 19 is stored as the LSB of the
identification word. Therefore, each receive message
requires two additional memory locations to allow the
RTMP to store the message successfully.
For example, a receive message with twelve data words
actually requires fourteen memory locations. Therefore, the
user needs to program the buffer size to be sixteen (24) since
buffer sizes defined in the BPD can only be a length of two
raised to an integer power from three to fifteen. If, on the
other hand, a receive message has fifteen data words, this
message actually requires seventeen memory locations. In
this case, the user must program a buffer size of 32 (25),
since this is the next power of two that accommodates
seventeen data words.
In the separate buffer mode of operation, the RTMP makes
all buffers the same length. Therefore, the host must be sure
to program the RTMP so the buffer size is large enough to
accommodate the largest message the RTMP can receive for
any subaddress.
4.5 RTMP Interrupt Functions
The RTMP has two outputs that provide the host subsystem
processor with interrupt control capability: (1) the End of
Receive/Transmit Message Activity (EORT) interrupt; and
(2) the End of Mode Code Activity (OEMC) interrupt. The
host subsystem can use these two outputs in conjunction
with the information the Operational Status Register (OPS)
provides to determine the condition of the RTMP after an
interrupt condition occurs.
RTMP-21
1553 BUS ACTIVITY
CWD1
DWD1
DWD2
DWD3
SWD
S/A=0A
CWD1
DWD4
DWD5
DWD6
DWD7
SWD
S/A=21
64K DATA RAM
0100H
64-WORD POINTER
BLOCK
ID WORD 1
1000H
1553 COMMAND
WORD
DWD1
DWD2
DWD3
RECEIVE POINTERS
(30)
101FH
SINGLE MODE
POINTER = 0100H
MODE CODE DATA
POINTER
TIME TAG 1
0105H
ID WORD 2
DWD4
DWD5
TRANSMIT POINTER
(30)
DWD6
DWD7
010AH
TIME TAG 2
Note:
After the RTMP stores the first set of data, the next
available address (0105H) is stored inlocation 10FH.
Figure 16a. RTMP Single Buffer Mode of Operation
The End of Receive/Transmit Message Activity (EORT)
interrupt is a maskable interrupt the user can select to occur
(1) only when the 1553 receive command activity is
complete; (2) only when the 1553 transmit command
activity is complete; or (3) when either receive or transmit
command activity is complete. The host masks the EORT
interrupt by resetting the appropriate bits (bit 11-IM1 and
bit 10-IM2) in the RTMP’s Control Register (CTL). IM1 =
0 keeps EORT from occurring at the end of receive
command activity. IM2 = 0 keeps EORT from occurring at
the end of transmit command activity. If the host does not
mask either IM1 or IM2, the EORT interrupt pulses low.
This pulse occurs at the end of either the receive or transmit
command activity.
The End of Mode Code Activity (EOMC) interrupt is a nonmaskable interrupt. The EOMC interrupt, like the EORT
interrupt, is also a low pulse, except the EOMC interrupt
occurs at the end of all memory accesses associated with
any 1553 mode code command. Both EORT and EOMC
require an external pull-up resistor and, if necessary, the user
can wire-OR the two outputs together to form a composite
RTMP interrupt.
RTMP-22
If any one of the following conditions occurs during normal
RTMP operation, the RTMP does not generate either the
EORT or the EOMC interrupt: (1) if a Message Error occurs;
(2) if a Framing (Overrun) Error occurs; (3) if the RTMP
receives an illegal 1553 command; (4) if the RTMP receives
a superseding command word; or (5) if the Busy bit in the
Control Register is set (1553B mode of operation only).
4.6 RTMP Error Detection Capabilities
The RTMP provides the host with significant errordetection capabilities. The RTMP can detect the following
types of errors:
Terminal Address Parity Errors
Framing or Overrun Errors
1553 Message Errors
4.6.1 Terminal Address Parity Errors
The RTMP can check the the Terminal Address parity inputs
(RTA4-RTA0) when the Terminal Address Parity Enable
(TAPEN) input is active high. If TAPEN = 1, then RTA4-
1553 BUS ACTIVITY
CWD1 DWD1 DWD2 DWD3
SWD
S/A=0A
CWD1 DWD4 DWD5 DWD6 DWD7
SWD
S/A=21
64K DATA RAM
0100H
64-WORD POINTER
BLOCK
1553 COMMAND
WORD
ID WORD 1
1000H
DWD1
DWD2
RECEIVE
POINTERS
SUBADDRESS OA
POINTER = 0100H
SUBADDRESS 21
POINTER = 0200H
DWD3
100AH
TIME TAG 1
1021H
0200H
ID WORD 2
DWD4
SUBADDRESS 30
POINTER
DWD5
DWD6
DWD7
TIME TAG 2
Figure 16b. RTMP Separate Buffer Mode of Operation
RTA0 and the Remote Terminal Parity (RTPTY) input must
provide the RTMP with odd parity, or the RTMP flags a
Terminal Address Parity Error. For example:
If the TA = 01000, then RTPTY must equal 0 to
prevent a parity error.
If the TA = 00110, then RTPTY must equal 1 to
prevent a parity error.
If the RTMP detects a Terminal Address Parity Error, this
error prevents the RTMP from recognizing any valid
commands on either channel, preventing the RTMP from
responding to a 1553 command word not actually intended
for this remote terminal.
4.6.2 Framing or Overrun Errors
A framing error occurs when the RTMP is not permitted to
access memory at a sufficient rate to service the
requirements of the 1553 data bus. For receive messages,
after the RTMP generates a DMA Request (DMAR) signal,
the host must generate a DMA Grant (DMAG) signal before
the RTMP receives the next incoming data word to prevent
a framing error. For transmit messages, after the RTMP
generates DMAR, the host must generate a DMAG before
the RTMP completes transmitting the previous 1553 data
word to prevent a framing error. When a framing error
occurs during a receive command, all RTMP memory
accesses cease. When a framing error occurs during a
transmit command, the RTMP terminates all data
transmissions.
The worst-case timing for receive commands requires the
RTMP to make four memory accesses within
40ms. The worst-case timing for transmit commands
depends on whether the RTMP is operating in 1553B or
1553A mode. When the RTMP is operating in the 1553A
mode, the worst-case timing requires the RTMP to make
three memory accesses within 22ms; when in the 1553B
mode, the worst-case timing requires the RTMP to make
three memory accesses within 28ms. The difference in the
timing here is due to the difference in the status word
response time between 1553A and 1553B.
The worst-case timing for a transmit command consists of
the remote terminal response time, which is modedependent, and the time it takes to transmit the 1553 status
word (20ms). During this time, the RTMP must fetch the
address pointer from the 64-word Pointer Block, store the
1553 command word in the first location of the Pointer
Block, then fetch the first data word from memory before it
completes transmitting the status word.
RTMP-23
When the RTMP detects a receive command word, it must
make four separate memory accesses before it receives the
second 1553 data word. The RTMP must (1) fetch the
appropriate address pointer from the 64-word Pointer
Block; (2) store the 1553 command word in the first location
of the Pointer Block; (3) store the identification word at the
memory location pointed to by the address pointer; and (4)
store the first received data word in the memory location
immediately after the identification word.
4.6.3 1553 Message Errors
The RTMP sets the Message Error bit in the 1553 status
word and also asserts the MERR output if the RTMP detects
a failure in one of the following areas.
1553 Data Word Tests:







Invalid sync field for any data word
Incorrect Manchester II format
Incorrect data word or command word parity
Too few data bits per word
Too many data bits per word
Too few data words per message
Too many data words per message (1553B
mode only)
 Non-contiguous data words
RT-to-RT Transfer Tests:
During an RT-to-RT command sequence, the RTMP
monitors the 1553 bus and compares the terminal address
of the transmit command word with the terminal address of
the status word from the transmitting RT. The RTMP
declares the RT-to-RT transfer invalid if no match occurs.
The RTMP then sets the Message Error bit. The RTMP also
sets the Message Error bit if it detects one of the following
errors:
 Data word transmission before the status
word transmission
 Excessive time before the transmitting RT sends
the status word
 Any deviation from the proper sequence of events
for RT-to-RT transfers
Illegal Mode Commands:
When the RTMP is operating in the 1553A mode, it does
not automatically declare any received mode code as illegal.
To illegalize any mode code, the RTMP outputs the Mode
Code/Subaddress outputs (MCSA0-MCSA4) along with
the Mode Code/Subaddress status signal (MC/SA). The host
uses these signals to decode when the RTMP receives a
mode code and what mode code was received. If the mode
code is illegal for this application, the host asserts the
RTMP’s Illegal Command (ILLCOM) input and the
Message Error bit is set in the RTMP’s 1553 status
word response.
RTMP-24
When the RTMP is operating in the 1553B mode, it
automatically illegalizes the following mode codes:
 Mode Code 00000 - Dynamic Bus Control
 Reserved Mode Codes 01001 through 01111 (no
associated data word)
 Reserved Mode Codes 10110 through 11111 (with
associated data word)
In these cases, the RTMP status word response has the
Message Error bit set.
4.7 RTMP Self-Test Functions
The RTMP performs a self-test by wrapping the encoder
output back into the decoder inputs. Self-test is either
internal or external to the RTMP. An internal self-test wraps
the RTMP encoder output back into the decoder input via a
multiplexer internal to the RTMP. External self-test loops
the RTMP encoder back into the decoder via the bus
transceiver. In normal operation the transceiver transmitter
is connected to the receiver. This connection closes the loop
from the encoder to decoder. Self-test has the ability to check
the function of Channel A and B, command recognition
logic, data transfer logic, and memory
address control.
The RTMP’s self-test capability is based on the fact that the
MIL-STD-1553 status word sync pulse is identical to the
command word sync pulse. Thus, if the status from the
encoder is fed back to the decoder, the RTMP will recognize
the status word as a command and thus cause the RTMP to
process the validated command word. After the host invokes
self-test, the RTMP self-test logic forces the transmission
of a status word even though the RTMP has not received a
valid command. By reading the RTMP’s Operational Status
Register the host can monitor self-test. The host compares
self-test results to expected results; data mismatches result
in self-test failure. Normal operation is inhibited
during self-test.
Anytime during the RTMP’s self-test execution, the host can
monitor the Operational Status Register’s (OPS) Self-Test
Active bit (STACT), bit 11. STACT=1 signifies that the
RTMP is performing a self-test. STACT is active until the
RTMP completes all self-test memory activity. If the host
has enabled the activity interrupts (EORT and EOMC),
EOMC occurs after the memory fetch for the data word that
the RTMP wraps around during the self-test, and EORT
occurs when the self-test is complete. Do not send mode
code commands in self-test while operating in the A mode.
In B mode the RTMP can verify 3 mode codes (Synchronize
with Data, Selected Transmitter Shutdown, Override
Selected Transmitter Shutdown). All of these mode codes
have the T/R bit set to zero.
Note: When monitoring self-test via the Operational Status
Register, each OPS read will clear any bits the RTMP set.
Control and invoke self-test by using the TEST input pin,
along with Control Register bits 12, 13, 14, and 15 (i.e.,
STCS, STEN, CHBEN, and CHAEN). Control Register bit
12, Self-test Channel Select (STCS), determines whether
internal self-test is performed on Channel A or Channel B.
Control external self-test channel select via Control Register
bit 12 (STCS) and Control Register bit 14 or bit 15. These
three bits determine which channel is active during self-test.
STCS identifies which channel, bit 15 or bit 14, enables the
hardware. Disable Channels A and B, via Control Register
bits 15 and 14, for internal self-test. Control Register bit 13,
Self-test Enable, initiates the self-test routine. See Control
Register bit descriptions for more information on the
function of bits 12 and 13. Input pin TEST determines
whether the self-test is external or internal (TEST = 1
external, TEST = 0 internal).
Note: External self-test will corrupt an operational bus since
a remote terminal transmits command word information.
Also note that bus activity received by the RTMP decoder
(specifically command word validation) will corrupt selftest.
After the host processor enables a self-test, the RTMP’s
internal self-test logic remains in a “wait” state until the
RTMP is not receiving or transmitting any information.
Once the RTMP determines that there is no 1553 bus
activity, the STEN bit of the Control Register is reset and
self-test begins.
Essentially, the self-test makes the RTMP behave as if it just
received a Transmit Vector Word mode code. The Transmit
Vector Word mode code tells the RTMP to transmit a status
word and one associated data word. The RTMP wraps this
status word and data word back around into the channel
under test. Since a status word and a command word have
the same sync pulse, when the RTMP decoder sees this
status word, the receiver thinks it has received a valid
command from the 1553 data bus.
The status word the RTMP transmits during the self-test,
which is wrapped around to the decoder as the 1553
command word, is host-programmable. The RTMP forces
bit 11 of this status word to logic zero, hence the status word
is recognized as a receive command word. All commands
used in self-test are receive commands. The host can
program bits 1 through 10 of this status word by writing to
bits 0 through 9 of the Control Register. When the RTMP’s
decoder sees these ten bits in the wrapped-around command
word, these bits are decoded as the command word’s
subaddress and word-count fields. Only one data word is
transmitted with the status word, therefore setting the word
count field not equal to 1 results in a message error.
The RTMP accesses the data word that it wraps around
during the self-test from memory just as it would any other
data word. The RTMP reads the data word for the wraparound test from the memory location to which the address
in the Mode Code Pointer (location 20H) points. The twelve
most significant bits of this address come from the data
programmed in the Mode Code Pointer location. The RTMP
always the four least significant address bits to zero
(Transmit Vector Word Mode Code).
The RTMP’s decoder on the selected test channel recognizes
the status word that is wrapped around during the self-test
as a valid 1553 receive command word. The RTMP’s
internal sequencer and error detection logic begin
processing the received command word and its associated
data in a normal sequence. The host programs the outgoing
status/command word to receive one data word at a specific
subaddress. Then the RTMP goes to the location in the 64word Pointer Block corresponding to the actual memory
location subaddress where the RTMP stores the data word
wrapped around during the self-test, if the host has chosen
the separate buffer mode of operation. If the host has
selected the single buffer mode of operation, the RTMP
stores the wrapped-around data word at the memory
location to which the Single Mode Data Pointer in the 64word Pointer Block points. The RTMP suppresses
transmitting a status word after receiving the wrappedaround command word and data word during self-test
execution. At this time, the self-test terminates and the
RTMP resets the Self-Test Active (STACT) bit in the
Operational Status Register.
The host has complete control over the RTMP’s self-test
processing and can terminate a self-test at any time by
performing a write to the Stop Self-test Register (SST).
When the host writes to the SST, the RTMP terminates all
memory activity, resets STEN, and resets the Self-Test
Active (STACT) bit in the OPS.
5.0 1553A AND 1553B
MODES OF OPERATION
The RTMP provides two modes of operation -- one to meet
the requirements of MIL-STD-1553A and another to meet
the requirements of MIL-STD-1553B. The user selects the
mode of operation for the specific application by
programming the 1553 mode select input (PRA/B). When
the host sets PRA/B = 1, the RTMP is in the 1553A mode
of operation. When PRA/B = 0, the RTMP is in the 1553B
mode of operation.
In either the 1553A or 1553B mode, the RTMP’s basic
operation remains the same with three major differences
among the modes of operation. These differences are: status
word bit definitions, mode code responses, and status word
response time.
RTMP-25
MC/SA
MCSA4
MCSA3
ILLEGAL
COMMAND
DECODER
MCSA2
MCSA1
RTMP
MCSA0
COMSTR
ILLCOM
Figure 17. Mode Code/Subaddress Illegalization Circuit
5.1 Status Word Bit Definition
When the RTMP operates in the 1553A mode, the only bits
of the status word it defines are the Message Error bit (bit
11) and the Terminal Flag bit (bit 1). The RTMP does not
specifically define the rest of the bits in the status word (bits
2 through 10). The user can define these bits for a specific
application by programming the corresponding bits in the
Control Register (CTL bits 1-9).
In the 1553B mode of operation, the RTMP defines all status
word bits in the CTL that correspond to a specific function
in the transmitted 1553 status word. The host controls some
of the status word bits in the CTL, namely the
Instrumentation, Service Request, Broadcast, Busy,
Subsystem Flag, and Terminal Flag bits. Finally, if the host
sets any undefined status word bits in the CTL, the RTMP
masks these bits (i.e., sets to logic zero) before they can be
transmitted in the status word.
5.2 Mode Code Responses
When the RTMP operates in the 1553A mode, it does not
internally detect any mode codes as being illegal. The
RTMP recognizes all other mode codes as being valid, and
responds to these mode codes with a status word only. The
1553A mode of operation does not support mode codes with
an associated data word.


Do not send mode codes with data to the RTMP
when operating in the 1553A mode.
No auto-execution of mode codes is performed in
the 1553A mode of operation.
The host can illegalize any mode code by decoding the
Mode Code/Subaddress outputs (MCSA0-4) and the MC/
SA output with an external device (figure 17). The host can
program the external decoder to generate the Illegal
RTMP-26
Command (ILLCOM) input whenever the RTMP receives
a mode code that the system declares illegal. Asserting
ILLCOM causes the RTMP to transmit a status word with
the Message Error bit set. Illegalization does not stop the
auto-execution of mode codes.
In the 1553B mode of operation, the RTMP internally
detects the Dynamic Bus Control mode code and all
reserved mode codes as illegal. The host can illegalize any
other mode code by setting the ILLCOM input, just as
described for the 1553A mode of operation.
Table 2 shows the action the RTMP takes for each of the
mode codes.
5.3 Status Word Response Time
When the RTMP operates in the 1553B mode, it checks to
see if too many data words are received while processing a
receive command. While operating in the 1553A mode, the
RTMP does not make this check. Therefore, the status word
response time for the RTMP in the 1553A mode is different
from the status word response time in the 1553B mode.
Operating in the 1553A mode, the RTMP’s status word
response time is from 4.25 to 5.75ms (reference figure 29).
This time is measured from midbit of the command word
parity bit to midbit of the status word sync pulse.
Operating in the 1553B mode, the RTMP’s status word
response time is from 9.25 to 10ms (reference figure 29).
This time is also measured from midbit of the command
word parity bit to midbit of the status word sync pulse.
These midbit-to-midbit response times are measured from
the midbit time of the parity bit at the RTMP’s inputs to the
midbit time of the sync pulse at the RTMP’s outputs. These
measurements do not include any delays attributable to
external devices such as transformers or transceivers.
Table 2. Mode Code Operation
Mode Code (7)
Number
Legal (L)/
Illegal (I)
Operation
(see below)
1553A
Mode
Dynamic Bus Control
Synchronize
Transmit Status Word
Initiate Self-Test
Transmitter Shutdown
Override Transmitter
Shutdown
Inhibit Terminal Flag Bit
Override Inhibit
Terminal Flag Bit
Reset Remote Terminal
00000
00001
00010
00011
00100
00101
I
L
L
L
L
L
1
2
3
2
3,8
3,8
L(2)
L(2)
L(2)
L(2)
L(2)
L(2)
00110
00111
L
L
3,8
3,8
L(2)
L(2)
01000
L
2
L(2)
Reserved
01001
01111
I
1
L(2)
Transmit Vector Word
Synchronize
Transmit Last Command
Transmit Bit Word
Selected Transmitter
Shutdown
Override Selected
Transmitter Shutdown (6)
10000
10001
10010
10011
10100
L
L
L
L
L
4
4
5
4
4
L(2)
N/A
L(2)
L(2)
N/A
No mode code with data
Status word only
10101
L
4
N/A
No mode code with data
Reserved
1011011111
I
1
L(2)
Notes
No mode code with data
Definition of operations:
1. The RTMP sets the Message Error bit, sends a status word, and stores the 1553
command word, but takes no internal action.
2. The RTMP sends a status word, stores the 1553 command word, but takes no
internal action
3. The RTMP sends a status word, stores the 1553 command word, and takes the
appropriate internal action.
4. The RTMP sends a status word, stores the 1553 command word, accesses memory
for the associated data word, but takes no internal action.
5. The RTMP sends a status word, updates the 1553 command word in an internal register,
accesses memory for the associated data word, but takes no internal action.
6. The RTMP must receive an Override Selected Transmitter Shutdown before the channel
that was disabled can be enabled.
7. Undefined mode codes in MIL-STD-1553B are illegalized.
8. Illegalized mode code is still executed.
6.0 RTMP SYSTEM INTERFACE
The RTMP system interface consists of the major functional
interfaces between the host processor and the RTMP. These
interfaces (1) allow the host to control the functions of the
RTMP and determine its operational status; (2) permit the
RTMP and the host to exchange the information from the
1553 data bus; and (3) allow the host to select the RTMP’s
terminal address.
The system interface provides a description of the following
aspects of the RTMP’s operation:
 Assigning the RTMP’s terminal address
 Controlling the RTMP’s DMA interface
 Interfacing with the RTMP’s internal registers
RTMP-27
DMAR
DMAG
AV
RRD or
RWR
Figure 18. General RTMP DMA Timing Relationships
6.1 Assigning the Terminal Address
The RTMP’s terminal address input pins (RTA0-RTA4) are
static inputs. This means the RTMP does not require a
latching signal of any sort to assign the RTMP its terminal
address. The host simply has to present the correct terminal
address on inputs RTA0-RTA4 and the RTMP recognizes
this as the terminal address for all 1553 command words.
The RTMP can check the parity of the assigned terminal
address by using the Remote Terminal Parity input
(RTPTY) and the Terminal Address Parity Enable input
(TAPEN) in conjunction with the RTA0-RTA4 inputs. In
most applications, it is important that the host enable the
terminal address parity checking input to prevent the RTMP
from inadvertently responding to a command word not
meant for it. If the host requires the RTMP to check the
parity of the terminal address, TAPEN must be high and
RTPTY must provide the RTMP with odd parity (an odd
number of high inputs) for the assigned terminal address.
If for some reason, such as a broken or missing terminal
address input or an inadvertent terminal address change, the
RTMP detects bad parity, it ignores all incoming command
words. The RTMP also sets bit 12 in the Operational Status
Register, the Parity Error (PAERR) bit. If the host can reestablish the correct terminal address and parity, the RTMP
resumes communication on the 1553 data bus.
6.2 Controlling the DMA Interface
The RTMP has a standard DMA interface that consists of a
set of three arbitration signals between the RTMP and the
host processor: (1) DMA Request (DMAR); (2) DMA Grant
(DMAG); and (3) DMA Enable (DMAEN). After the bus
controller grants the RTMP control of the address and data
buses, the RTMP uses three additional signals to control the
shared memory: (1) RAM Read (RRD); (2) RAM Write
(RWR); and (3) Address Valid (AV). Figure 18 shows the
general relationship of these signals during bus arbitration
and data acquisition.
RTMP-28
When the RTMP requires access to the shared memory, it
initiates the bus arbitration sequence by generating DMAR.
For a transmit message, the RTMP generates DMAR when
the internal transmitter buffer is empty. Therefore, the
RTMP must be granted control of the data bus before the
current data word transmission is finished or an overrun
error occurs. The RTMP continues to generate DMARs until
it has transmitted the proper number of data words or until
an error condition occurs. For a receive message, the RTMP
generates DMAR after a received data word is validated. In
this situation, the RTMP must receive a bus grant signal
before receiving the next data word or an overrun
error occurs.
After the RTMP generates DMAR, it waits until the bus
master generates DMAG. After the bus master generates
DMAG, bus arbitration is complete (provided DMAEN is
high) and the RTMP takes control of the address and data
buses by first enabling the address three-state buffers. After
the address lines have settled, the RTMP generates AV
signifying the address is valid.
The next step in the sequence depends on whether the
present memory access is for a receive or a transmit
message. If the RTMP is processing a receive command,
RWR goes active allowing the RTMP to write the received
1553 data to the shared memory. If, on the other hand, the
RTMP is processing a transmit command, RRD goes active
allowing the RTMP to access data from the shared memory.
In either case, the data is read from or written to shared
memory on the rising edge of RRD or RWR, respectively,
thus signifying the end of this memory access cycle.
If a memory access bus cycle is pending, i.e., the RTMP has
generated DMAR but the bus controller has not
acknowledged with a DMAG, four events can terminate the
current bus cycle: (1) the RTMP receives a superseding 1553
command word on the same or opposite channel; (2) an
overrun error occurs; (3) a message error occurs; or (4) a
write to the Stop Self-Test (SST) Register occurs.
6.3 Interfacing with the RTMP’s Internal Registers
The host interfaces with the RTMP’s six internal registers
to control the RTMP’s operation and to determine the
RTMP’s operational status while the RTMP is active. Six
signals between the host and the RTMP control this
interface: (1) the three least significant address lines (A2A0); (2) Chip Select (CS); (3) register read (RD); and (4)
register write (WR). Figure 19 shows the general timing
relationship of these signals. The RTMP’s three least
significant address bits (A2-A0) are bidirectional. When the
host drives these inputs along with CS, RD, and WR, the
RTMP uses this information to select which of its six
internal registers the host will access during this operation
(table 1).
Before the host attempts to access the RTMP’s internal
registers, it must make sure the RTMP is not performing a
DMA operation. Accessing the RTMP’s internal registers
during a DMA operation causes data corruption because the
CS input takes precedence over all other RTMP memory
operations and causes the RTMP immediately to place its
address and data buffers in a high-impedance state.
Therefore, after the bus master has granted the RTMP
control of the buses, the host must not attempt any internal
register reads or writes until the RTMP completes its
memory operation.
The interface timing between the host and the RTMP’s
internal registers follows standard microprocessor
interfacing techniques. After the host has determined that
the RTMP is not using the address and data buses, it
generates the address for the selected RTMP internal
register. The host asserts CS, informing the RTMP that an
internal register operation is about to occur. The RTMP
responds by placing its address and data bus signals in a
high-impedance state and allowing the three least
significant address lines to become inputs.
At this point, the host asserts either RD or WR telling the
RTMP the direction of the data flow. The host completes
the current register access cycle on the rising edge of WR
for data input operations and on the rising edge of RD for
data output operations.
6.4 RTMP Hardware Interface
6.4.1 The RTMP - 1553 Transceiver Interface
The RTMP’s Manchester II encoder/decoders interface
directly with the 1553 bus transceiver as shown in figure
20. The RTMP uses the RAO, RAZ, TAO, and TAZ pins to
interface with bus Channel A. The RTMP uses the RBO,
RBZ, TBO, and TBZ pins to interface with bus Channel B.
The RTMP’s encoder outputs (TAO, TAZ, TBO, and TBZ)
are low when they are inactive.
In addition to the signals listed above, the RTMP also
provides two signals that assist the RTMP in meeting the
MIL-STD-1553 fail-safe timer requirements. These signals
are the Timer On (TIMERON) and the Channel A/ (CHA/
B) outputs. These signals are also shown in figure 20.
6.4.2 The RTMP DMA Interface
When the RTMP is in its standard DMA configuration, its
address, data, and control signals are directly connected to
each other as shown in figure 21. The RTMP’s signals
remain in a high-impedance state until the RTMP is granted
control of the buses after DMA arbitration has occurred, or
until the host asserts CS signifying that the host is about to
access one of the RTMP’s internal registers.
The host can disable all DMA transfers by setting the Busy
bit (bit 3) of the Control Register (CTL).
CS * RD
DATA
BUS
Figure 19a. General RTMP Register Read Timing
ADDRESS
BUS
CS * WR
DATA
BUS
Figure 19b. General RTMP Register Write Timing
RTMP-29
RAO
CHANNEL A
RAZ
¤
TXINHA
CHANNEL A
TAO
TAZ
¤
UTMC
63M125
RTMP
RBO
CHANNEL B
RBZ
¤
TXINHB
CHANNEL B
TBO
TBZ
¤
CHANNEL
DISABLE
LOGIC
TIMERON
CHA/B
Figure 20. RTMP-to-Transceiver Interface Diagram
RAM
A0-A2
A3-A15
RRD
RWR
RD
RTMP
WR
CS
DATA
DMAR
DMAG
3
13
16
16


16
HOST

16
16
Figure 21. RTMP-to Host Interface
RTMP-30
16
7.0 OPERATING CONDITIONS*
(REFERENCED TO VSS)
SYMBOL
VDD
VI/O
PARAMETER
LIMITS
UNIT
DC supply voltage
-0.3 to +7.0
V
Voltage on any pin
-0.3 to VDD +0.3
V
10
mA
II
DC input current
TSTG
Storage temperature
PD
Power dissipation

TJ
Thermal resistance, junction-to-case
Maximum junction temperature
-64 to +150
300
C
mW
10
C/W
+175
C
* Stresses outside the listed absolute maximum ratings may cause permanent damage to the device. This is a stress rating only,
and functional operation of the device at these or any other conditions beyond limits indicated in the operational sections of
this specification is notrecommended. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
RECOMMENDED OPERATING CONDITIONS
SYMBOL
VDD
TA
FO
VIN
PARAMETER
LIMITS
UNIT
DC supply voltage
Temperature range
Operating frequency
DC input voltage
4.5 to 5.5
V
-55 to +125
C
12 .01%
MHz
V
0 to VDD
RTMP-31
8.0 DC ELECTRICAL CHARACTERISTICS
SYMBOL
VIL
VIH
IIN
VOL
VOH
IOZ
PARAMETER
CONDITION
Low-level input voltage
TTL inputs
High-level input voltage
TTL inputs
Input leakage current
VIN = VDD or VSS
TTL inputs
Inputs with pull-down resistorsVIN = VDD
Inputs with pull-down resistorsVIN = 2.4V
Inputs with pull-up resistors VIN = VSS
Low-level output voltage
IOL = 3.2mA
TTL outputs
High-level output voltage
TTL outputs
IOH = -400mA
Three-state output leakage
current
VO = VDD or VSS
TTL outputs
IOS
Short-circuit output current
CIN
Input capacitance
COUT
Output capacitance
CIO
Bidirect I/O capacitance
IDD
Average operating current
QIDD
Quiescent current
2, 5
1
1
1
3, 5
MINIMUM
MAXIMUM
0.8
2.0
-1
80
-1000
UNIT
V
V
1
1000
400
-80
0.4
A
A
A
A
V
V
2.4
+10
A
100
mA
mA
F = 1MHz @ 0V
10
pF
F = 1MHz @ 0V
15
pF
F = 1MHz @ 0V
20
pF
F = 12MHz, CL = 50pF
50
mA
1
mA
VDD = 5.5V, VO = VDD
VDD = 5.5V, VO = 0V
See Note 4
-10
-100
Notes:
1. Measured only for initial qualification and after process or design changes which may affect input/output capacitance.
2. Not more than one output may be shorted at a time for a maximum duration of one second.
3. Includes current through input pull-ups. Instantaneous surge currents on the order of 1 amp can occur during output switching.
Voltage supply should be adequately sized and decoupled to handle a large current surge.
4. All inputs with internal pull-ups and pull-downs should be left floating. All other inputs should be tied high or low.
5. Guaranteed by design or characterization.
RTMP-32
9.0 AC ELECTRICAL CHARACTERISTICS
V MIN
INPUT IH
1
tb
ta
IN-PHASE
OUTPUT
OUT-OF-PHASE
OUTPUT
VIH MIN
1
2
td
2
tc
VOH MIN
2
VOH MIN
2
te
VOH MIN
BUS
tf
tg
th
SYMBOL
ta
tb
PARAMETER
INPUT
INPUT
INPUT
INPUT
INPUT
INPUT
INPUT
INPUT
tc
td
te
tf
tg
th
to response
to response
to response
to response
to data valid
to high Z
to high Z
to data valid
Notes:
1. Timing measurements made at (VIH MIN + VIL MAX)/2.
2. Timing measurements made at (VOL MAX + VOH MIN)/2
3. Based on 50pF load.
4. Unless otherwise noted, all AC electrical characteristics are guaranteed by design or characterization.
Figure 22. Typical Timing Measurements
5V
IREF (source)
90%
3V
90%
VREF
50pF

10%
10%
0V
IREF (sink)
< 2ns
< 2ns
Input Pulses
Note:
50pF including scope probe and test socket
Figure 23. AC Test Loads and Input Waveforms
RTMP-33
DMAR
t22a
DMAG
t22b
t22j
VALID ADDRESS
ADDRESS
BUS
t22i
t22c
AV
t22d
t22h
t22e
RRD
t22f
t22g
DATA
BUS
VALID DATA
SYMBOL
PARAMETER
MIN
MAX
UNITS
t22a
DMAR to DMAG
0
7.3
s
t22b (1)
DMAGto Address Bus Valid
0
134
ns
t22c
Address Bus Valid to AV
40
176
ns
t22d
AV to RRD
80
90
ns
t22e
RRD Pulsewidth
95
140
ns
t22f
Data Setup Time to RRD
50
ns
t22g
Data Hold Time from RRD
0
ns
t22h
RRD to AV
t22i
t22j
32
70
ns
AV to Address High-Impedance (Hold) and DMAR
0
62
ns
AV to DMAG
0
Note:
1. Guaranteed by test.
Figure 24. Detailed Timing - RTMP DMA Read Cycle
RTMP-34
ns
DMAR
t23a
DMAG
t23b
t23j
VALID ADDRESS
ADDRESS
BUS
t23i
t23c
AV
t23d
t23h
t23e
RWR
t23f
t23g
VALID DATA
DATA
BUS
SYMBOL
PARAMETER
MIN
MAX UNITS
t23a
DMAR to DMAG
0
7.3
s
t23b 1
DMAGto Address Bus Valid
0
134
ns
t23c
Address Bus Valid to AV
40
176
ns
80
90
ns
95
140
ns
t23d
AV to RWR
t23e
RWR Pulsewidth
145
311
ns
Data Setup Time to RWR
20
90
ns
t23h
RWRto Data Bus High-Impedance
32
70
ns
t23i
RWR to AV
0
62
ns
t23f
t23g
0
t23j
ns
Figure 25. Detailed Timing - RTMP DMA Write Cycle
ADDRESS
BUS
VALID ADDRESS
t24a
t24d
CS*RD
t24c
t24b
DATA
BUS
VALID DATA
SYMBOL
t24a
t24b
PARAMETER
Address Bus Valid to (CS*RD)
1
(CS*RD)to Data Bus Valid
MIN
MAX UNITS
20
ns
0
93
ns
100
ns
t24c
(CS*RD)to Data Bus High-Impedence
10
t24d
(CS*RD)to Address Bus High-Impedence
20
ns
Note:
1. Guaranteed by test.
Figure 26. Detailed Timing X0106 RTMP Register Reads
RTMP-35
VALID ADDRESS
ADDRESS
BUS
t25
t25
t25
CS+WR
t25
DATA
BUS
t25
VALID DATA
PARAMETER
SYMBOL
t25
t25
t25
t25
t25
MIN
MAX
UNITS
Address Bus Valid to (CS+WR)
WR Pulsewidth
80
ns
50
ns
WR to Data Bus High-Impedance (Hold time)
(CS*WR) to Address Bus High-Impedance
Data Valid to (CS*WR)(Set-up Time)
70
ns
50
ns
20
ns
Figure 27. Detailed Timing - RTMP Register Writes
1553
CMD WD
t26
COMSTR
t26
CHA/B
t26
MCSA0-4
t26
t26
ILLCOM
t26
SME
SYMBOL
PARAMETER
MIN
MAX
3.7
Mid-bit of Command Word Parity to COMSTRØ
UNITS
s
t26a
COMSTR Pulsewidth
240
ns
t26b
CHA/B Valid to COMSTR¦
230
ns
t26c
MCSA0-4 Valid to COMSTR¦
240
t26d
COMSTR¦ to ILLCOM¦ (Active)
100
ns
t26e
COMSTR¦ to SME¦ (Active)
500
ns
t26f
SME
1.0
s
.100
Figure 28. 1553 Command Strobeand Channel Timing
RTMP-36
t26
ns
1553
CMD WD
tRESP 1
1553
STATUS WORD
SYMBOL
PARAMETER
tRESP
(PRA/B=1)
tRESP
(PRA/B=0)
MIN
MAX
UNITS
1553A Mode Status Word Response Time
4.25
5.75
s
1553B Mode Status Word Response Time
9.25
10.0
s
Note:
1. This timing is for RTMP signals only and does not include delays from other sources.
Figure 29. 1553 Status Word Response Times
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
1
1
1
1
1
1
1
1
1
1
1
1
PAR
1
1
TFLG
TERMINAL
ADDRESS
1
0
SWB18
SYNC
9
SWB17
5
8
SWB16
7
SWB15
6
SWB14
5
SWB13
4
SWB12
STATUS
WORD
3
SWB11
2
SWB10
1
MESSAGE ERROR
BIT
TIMES
Figure 30. Status Word Bit-Time Definitions for 1553A Mode
RTMP-37
BIT TIMES
1
2
3
4
5
6
7
8
5
COMMAND WORD
SYNC
9
10
11
1
12
13
14
15
16
5
REMOTE TERMINAL T/R
ADDRESS
SUBADDRESS/
MODE
17
18
19
5
20
1
DATA WORD
P
COUNT/MODE CODE
DATA WORD
SYNC
DATA
P
RTMP-38
PARITY
TERMINAL FLAG
SUBSYSTEM FLAG
DYNAMIC BUS CONTROLACCEPTANCE
Figure 31. MIL-STD-1553B Word Formats
BUSY
RESERVED
BROADCAST COMMAND RECEIVED
SERVICE REQUEST
Note:
T/R - transmit/receive
P - parity
REMOTE TERMINAL
ADDRESS
INSTRUMENTATION
SYNC
MESSAGE ERROR
STATUS WORD
8
7
4
5
3
2
1
D13
D14
D15
RTA0
RTA1
RTA2
6
V DD
D10
D11
D12
D7
D8
D9
V SS
9
D5
D6
D0
D1
D2
D3
D4
11 10
84 83 82 81 80 79 78 77 76 75
PRA/B
12
74
ENBC
TEST
MCSA0
MCSA1
MCSA2
MCSA3
MCSA4
VSS
13
73
14
72
15
71
16
70
17
69
18
68
19
67
20
66
MC/SA
21
65
RTA3
RTA4
TAPEN
RTPTY
A0
A1
A2
A3
VDD
A4
ILLCOM
RAO
VDD
22
64
A5
23
63
24
62
RAZ
TAO
25
61
26
60
A6
VSS
A7
A8
A9
A10
A11
A12
A13
A14
TAZ
27
59
CHA/B
TIMERON
28
58
29
57
TBO
TBZ
RESET
30
56
31
55
32
54
DMAG
DMAEN
RRD
RWR
AV
A15
CS
RD
WR
DMAR
V SS
V DD
RBO
RBZ
CLK
EORT
EOMC
COMSTR
MERR
SVC
SME
33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53
Figure 32a. Leadless Chip Carrier Functional Pin Identification (Top View)
RTMP-39
D0
TEST
MCSA0
MSCA2
VVSS
RAO
DD
VDD
TAZ
TIMERON
TBO
RESET
K
D2
PRA/B
ENBC
MCSA1
MCSA4
MCSA3
RAZ
CHA/B
TBZ
RBO
CLK
J
D3
D1
MC/SA
ILLCOM
TAO
RBZ
EORT
H
D5
D4
EOMC
COMSTR
G
D8
D7
D6
MERR
SVC
SME
F
D9
D12
VSS
VDD
VSS
DMAR
E
D10
D8
D11
VDD
CS
WR
RD
D
D13
D14
DMAEN
DMAG
C
D15
RTA1
AV
RRD
B
RTA0
RTA2
RTA4
A
RTA3
BURST
TAPEN
SSYSF
1
2
L
A4
A5
A8
A0
A3
A6
A7
A10
A13
A14
RWR
RTPTY
A1
VDD
A2
VSS
A9
A11
A12
A15
3
4
5
6
7
8
9
10
INDEX
CORNER
Figure 32b. Pingrid Array Functional Pin Identification (Bottom View)
RTMP-40
11