mc68hc912bd32 Freescale Semiconductor, Inc, mc68hc912bd32 Datasheet - Page 183

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

13-sibus
Figure 31 FIFO Status (empty, not empty, overrun) - Example with 3 buffers
BUFFERS:
MESSAGES:
FIFO EMPTY
PUTIDX
(WRITE)
GETIDX
(READ)
0
-
To read a Receive FIFO buffer the FIFO must be locked by setting the
LOCK bit of buffer 0. The message buffer addressed by GETIDX
appears in the Active Receive FIFO Buffer window in the memory map.
After reading the FIFO must be unlocked and the GETIDX will be
incremented.
There is a programmable identifier acceptance filter for the Receive
FIFO system. The FIFO identifier acceptance register (FIDAC) defines
the acceptable pattern of the identifier to be received. The FIFO identifier
mask register (FIDMR) specifies which of the corresponding bits are
marked ‘don’t care’ for acceptance filtering.
There is also a programmable identifier rejection filter for the Receive
FIFO system. The FIFO identifier rejection register (FIDRJ) defines the
acceptable pattern of the identifier to be rejected. The FIFO identifier
rejection mask register (FIDRMR) specifies which of the corresponding
bits are marked ‘don’t care’ for rejection filtering.
If acceptance and rejection filter are configured to match the same
identifier, the message will be rejected.
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Freescale Semiconductor, Inc.
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BUFFERS:
MESSAGES:
Byteflight™ Module
FIFO NOT EMPTY
GETIDX
(READ)
0
A
PUTIDX
(WRITE)
1
-
2
-
BUFFERS:
MESSAGES:
PUTIDX WAS INCREMENTED LAST
+ NEW INCOMING MESSAGE (WHICH
IS LOST)
FIFO OVERRUN
PUTIDX
(WRITE)
GETIDX
(READ)
MC68HC912BD32 Rev 1.0
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A
Functional Overview
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B
Byteflight™ Module
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C