Aim MIL-STD-1553 - Low Speed Functions; Apicmdbcacycprep

MIL-STD-1553 Reference Manual
195
Chapter 7 – Bus Controller Functions
7.1 Low Speed Functions
7.1.1 ApiCmdBCAcycPrep
Prototype:
AiInt16 ApiCmdBCAcycPrep ( AiUInt32 ul_ModuleHandle, AiUInt8 biu,
TY_API_BC_ACYC *pacyc );
Driver Command:
API_BC_ACYC_MSG_PREP (0x7E)
Purpose:
This function is used to define the content of the acyclic ‘on-the-fly’ minor frame to be
inserted into the normal BC framing sequence. It is similar to the
ApiCmdBCFrameDef function. Transmission of the specified acyclic minor frame is
started using the ApiCmdBCAcycSend function.
I
I
n
n
p
p
u
u
t
t
T
T
Y
Y
_
_
A
A
P
P
I
I
_
_
B
B
C
C
_
_
A
A
C
C
Y
Y
C
C
*
*
p
p
a
a
c
c
y
y
c
c
BC Acyclic Frame description
typedef struct ty_api_bc_acyc
{
AiUInt8 cnt;
AiUInt8 padding1;
AiUInt16 instr[MAX_API_BC_XACYC];
AiUInt16 xid[MAX_API_BC_XACYC];
} TY_API_BC_ACYC;
A
A
i
i
U
U
I
I
n
n
t
t
8
8
c
c
n
n
t
t
Value
Description
1..127
Amount of instructions in Acyclic Minor Frame
A
A
i
i
U
U
I
I
n
n
t
t
8
8
p
p
a
a
d
d
d
d
i
i
n
n
g
g
1
1
Reserved (0)
A
A
i
i
U
U
I
I
n
n
t
t
1
1
6
6
i
i
n
n
s
s
t
t
r
r
[
[
]
]
Value
Constant
Description
1
API_BC_INSTR_TRANSFER
BC Transfer Instruction
 Used for normal transfers
2
API_BC_INSTR_SKIP
BC Skip Instruction
The skip instruction is a relative, unconditional branch
forward. This means, that the instruction execution is
continued n instruction after the location of the skip
instruction, whereby n is equal to the value set in
‘xid[]’.
This instruction is also intended to be used as a ‘No
Operation’ instruction with interrupt capability (with
“Skip Count=1” and interrupt enabled in ‘xid[]’)
Note: This instruction may be used to
implement larger delays, if using this
instruction alone in a minor frame!
4
API_BC_INSTR_STROBE
BC external Strobe Instruction
If this instruction is executed, the BC trigger output of
the board is pulsed. After this operation, the
instruction execution continues with the following
instruction.
A
A
i
i
U
U
I
I
n
n
t
t
1
1
6
6
x
x
i
i
d
d
[
[
]
]