mc68hc912bd32 Freescale Semiconductor, Inc, mc68hc912bd32 Datasheet - Page 202

• Manufacturer Part Number: mc68hc912bd32
• Description: 16-bit Device Composed Of Standard On-chip Peripherals
• Manufacturer: Freescale Semiconductor, Inc

Byteflight™ Module
MC68HC912BD32 Rev 1.0
ABTRQ — Abort Request
ABTAK — Abort Acknowledge
LOCK — Message Buffer Lock
The CPU sets the ABTRQ bit to request that a full transmit buffer
(IFLG = 0) is aborted. The request is granted at the next sync pulse if
the buffer is still full. The IFLG and the ABTAK flag are set when the
message is aborted. The ABTRQ bit is cleared implicitly by setting of
the IFLG.
This flag acknowledges that a message has been aborted due to a
pending abort request from the CPU. The message is aborted at the
next sync pulse if the request was pending before the this sync pulse.
The application software can use this flag to determine if the message
has been sent out or has been aborted. The ABTAK flag is cleared
implicitly by clearing the IFLG, i.e. the buffer has been set up again.
The bit has various functions depending on the configuration of the
corresponding message buffer.
If the buffer is configured as receive buffer and the CPU wants to
access the buffer it has to lock it first to prevent an overwrite . The
locking is done by writing a “1” to the LOCK bit. Only one receive
buffer must be locked at a time. The buffer is released by writing a ‘0’
to the lock bit.
If the buffer is configured as transmit buffer and the CPU wants to
access the buffer it has to lock it first. The locking is done by writing a
“1” to the LOCK bit. Only one transmit buffer must be locked at a time.
The buffer is released by writing a ‘0’ to the lock bit. The request to
lock a full tranmit buffer (IFLG = 0) is granted as soon as the buffer
has been transmitted.
If there are buffers configured as receive FIFO the LOCK bit of buffer
0 is used for locking the FIFO. Writing a ‘1’ locks the FIFO, no
verifying is required. The lock controls the GETIDX. The FIFO buffer
addressed by the GETIDX is “visible” in the memory map. The
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1 = Abort request pending.
0 = No abort request.
1 = The message has been aborted.
0 = The message has not been aborted, thus has been sent out.
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Byteflight™ Module
32-sibus