HI-6130_16 Datasheet, PDF (59/296 Pages) Holt Integrated Circuits – 3.3V BC / MT / RT Multi-Terminal Device

HI-6130, HI-6131
These instructions control program execution: Halt, Jump, Subroutine Call and Subroutine Return. Subroutine calls
can be nested 8 levels deep. If BC Call Stack overflow or underflow occurs, device logic generates a CSTKERR (Call
Stack Pointer Error) interrupt, if enabled. Other host interrupts are generated under program control using the Interrupt
Request instruction. In this case, a 4-bit user-defined interrupt code is written to the BC Interrupt Request Bits 3-0 in
the BC Pending Interrupt Register.
Other instructions are formed various duties: set, reset or toggle General Purpose Flag bits; load the Time Tag counter;
load the Frame Time counter; begin a new BC frame; wait for external trigger, then start a new BC frame; evaluate
remaining Frame Time; or evaluate time to next message.
Table 7.  Bus Controller Instruction Op Codes
Name Instruction
XEQ
Execute
Message
Conditional
Op
Code
0x01
Parameter
Function
RAM Address for
Message Control/
Status Block
If the Condition Code evaluates True, execute the message
at the parameter-specified Message Control Status Block
address. Otherwise (Condition Code Evaluates False),
continue execution at the next op code in the BC Instruction
List.
At the start of XEQ message execution, if the fourth word in
the Message Control/Status Block is nonzero, it is copied to
the BC Time to Next Message Register, and message timer
begins decrementing. The BC message sequencer does not
fetch the next instruction op code until the message timer
reaches zero.
Regarding Condition Codes used with XEQ:
• If using LT, GT-EQ, EQ and NE (which are only
modified by the device upon completion of CMT or CFT
op codes) the host must not change the value of the
shared function GP0 or GP1 flag bit during execution of
the contingent message.
• If using GP Flag Bit status (GP0 through GP7) to enable
a message, host must not alter the tested GP Flag bit
during execution of a contingent message.
• The ALWAYS and NEVER Condition Codes may be
used with XEQ. The following Condition Codes must
not be used with XEQ: BADMSG, RETRY1 or RETRY2,
NORESP, MSKSTATSET, FMTERR or GOODBLOCK.
HOLT INTEGRATED CIRCUITS
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