GR740-UM-DS, Nov 2017, Version 1.7
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GR740
16.5.3 Mode Codes
Which of the MIL-STD-1553B mode codes that are legal and should be logged and interrupted are
controlled by the RT Mode Code Control register. As for data transfers, to enable interrupts you must
also enable logging. Inhibit mode codes are controlled by the same fields as their non-inhibit counter-
part and mode codes that can be broadcast have two separate fields to control the broadcast and non-
broadcast variants.
The different mode codes and the corresponding action taken by the RT are tabulated below. Some
mode codes do not have a built-in action, so they will need to be implemented in software if desired.
The relation between each mode code to the fields in the RT Mode Code control register is also
shown.
Table 295.
RT Mode Codes
Mode code
Description
Built-in action, if mode code is enabled
Can
log/
IRQ
Enabled
after
reset
Ctrl.
reg
bits
0
00000
Dynamic bus control
If the DBCA bit is set in the RT Bus Status register,
a Dynamic Bus Control Acceptance response is
sent.
Yes
No
17:16
1
00001
Synchronize
The time field in the RT sync register is updated.
The output rtsync is pulsed high one AMBA cycle.
Yes
Yes
3:0
2
00010
Transmit status word
Transmits the RT:s status word
Enabled always, can not be logged or disabled.
No
Yes
-
3
00011
Initiate self test
No built-in action
Yes
No
21:18
4
00100
Transmitter shutdown
The RT will stop responding to commands on the
other bus (not the bus on which this command was
given).
Yes
Yes
11:8
5
00101
Override transmitter
shutdown
Removes the effect of an earlier transmitter shut-
down mode code received on the same bus
Yes
Yes
11:8
6
00110
Inhibit terminal flag
Masks the terminal flag of the sent RT status words Yes
No
25:22
7
00111
Override inhibit termi-
nal flag
Removes the effect of an earlier inhibit terminal
flag mode code.
Yes
No
25:22
8
01000
Reset remote terminal
The fail-safe timers, transmitter shutdown and
inhibit terminal flag inhibit status are reset.
The Terminal Flag and Service Request bits in the
RT Bus Status register are cleared.
The extreset output is pulsed high one AMBA
cycle.
Yes
No
29:26
16
10000
Transmit vector word
Responds with vector word from RT Status Words
Register
Yes
No
13:12
17
10001
Synchronize with data
word
The time and data fields in the RT sync register are
updated. The rtsync output is pulsed high one
AMBA cycle
Yes
Yes
7:4
18
10010
Transmit last command Transmits the last command sent to the RT.
Enabled always, can not be logged or disabled.
No
Yes
-
19
10011
Transmit BIT word
Responds with BIT word from RT Status Words
Register
Yes
No
15:14
20
10100
Selected transmitter
shutdown
No built-in action
No
No
-
21
10101
Override selected
transmitter shutdown
No built-in action
No
No
-