AN2283 Freescale Semiconductor / Motorola, AN2283 Datasheet - Page 20

• Manufacturer Part Number: AN2283
• Description: Scalable Controller Area Network (MSCAN)
• Manufacturer: Freescale Semiconductor / Motorola

AN2283/D
20
Motorola Scalable Controller Area Network (MSCAN) Interrupts
IDAM1–IDAM0 — Identifier Acceptance Mode
IDHIT2–IDHIT0—Identifier Acceptance Hit Indicator
Figure 15. MSCAN08 Identifier Acceptance Control Register (CIDAC)
Figure 16. MSCAN12 Identifier Acceptance Control Register (CIDAC)
2. The hardware identifier acceptance filters are applied to the successfully
3. When a message finds a filter match, the RxBG becomes the RxFG and
The CPU sets these flags to define the identifier acceptance filter
organization. In the filter closed mode, no messages will be accepted so that
the RxFG buffer will never be reloaded. See
The MSCAN sets these flags to indicate an identifier acceptance hit. The
IDHIT indicators are always related to the message in the RxFG buffer.
When a message gets copied from RxBG to RxFG the indicators are
updated as well. See
Freescale Semiconductor, Inc.
Bit 7
Bit 7
0
0
For More Information On This Product,
received message in the RxBG. The Identifier of the message is
compared with the hardware filters, composed of the acceptance and
mask registers. The mask register specifies which particular bits to
compare in the acceptance registers with the identifier of the message.
For more details on hardware acceptance filters, refer to Using The
Motorola msCAN Filter Configuration Tool (Motorola document order
number AN2010/D).
is accessible by the CPU only if the Receive Buffer Full (RXF) bit in the
CRFLG is clear (RXF = 0) indicating that the prior receive buffer (RxFG)
was empty. The MSCAN Identifier Acceptance Control Register
(CIDAC) is used to set the Identifier Acceptance Mode. CIDAC also
indicates which identifier acceptance filter was hit by the message in the
RxFG buffer that passed through the hardware filters. This information
is imperative when performing additional filtering through software. If the
message doesn’t match one of the hardware filters then the message is
discarded in the RxBG buffer and MSCAN can attempt to receive the
next message into this buffer.
The CIDAC registers for the MSCAN08 and MSCAN12 are shown in
Figure 15
Go to: www.freescale.com
6
0
6
0
and
Figure
IDAM1
IDAM1
5
5
Table 9
16. Note that they are different.
IDAM0
IDAM0
and
4
4
Table
3
0
3
0
10.
Table 7
IDHIT2
2
0
2
and
Table
IDHIT1
IDHIT1
1
1
MOTOROLA
8.
IDHIT0
IDHIT0
Bit 0
Bit 0