GR740-UM-DS, Nov 2017, Version 1.7 249 www.cobham.com/gaisler
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 17:1 6
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 25:2 2
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 29:2 6
16 10000 Transmit vector word Responds with vector word from RT Status Words
Register
Yes No 13:1 2
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 15:1 4
20 10100 Selected transmitter
shutdown
No built-in action No No -
21 10101 Override selected
transmitter shutdown
No built-in action No No -
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