Infineon Technologies TC1784, Руководство пользователя

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TC1784
FlexRay™ Protocol Controller (E-Ray)
User´s Manual 20-227 V1.1, 2011-05
E-Ray, V3.13
overwrites the oldest message in the FIFO. This will set FIFO overrun flag RFO in the
Error Service Request Register.
Figure 20-10 FIFO Status: Empty, Not Empty, Overrun
A FIFO non empty status is detected when the PUT index (PIDX) differs from the GET
index (GIDX). In this case flag RFNE is set. This indicates that there is at least one
received message in the FIFO. The FIFO empty, FIFO not empty, and the FIFO overrun
states are explained in
Figure 20-10 for a three Message Buffer FIFO.
There is a programmable FIFO rejection filter for the FIFO. The FIFO Rejection Filter
register (FRF) defines a filter pattern for messages to be rejected. The FIFO rejection
filter consists of channel filter, Frame ID filter, and cycle counter filter. If bit RSS is set
to 1 (default), all messages received in the static segment are rejected by the FIFO. If bit
RNF is set to 1 (default), received NULL Frames are not stored in the FIFO.
The FIFO Rejection Filter Mask register (FRFM) specifies which bits of the Frame ID
filter in the FIFO Rejection Filter register are marked “don’t care” for rejection filtering.
20.6.10.2 Configuration of the FIFO
For all Message Buffers belonging to the FIFO the data pointer to the first 32-bit word of
the Data Section of the respective Message Buffer in the Message RAM has to be
configured via the Write Header Section 3 register. All information required for
acceptance filtering is taken from the FIFO rejection filter and the FIFO rejection filter
mask and needs not be configured in the Header Sections of the Message Buffers
belonging to the FIFO.
When programming the data pointers for the Message Buffers belonging to the FIFO, the
payload length of all Message Buffers should be programmed to the same value.
1 2 3
A - -
Buffers
Messages
FIFO empty FIFO not empty FIFO overrun
1 2 3
A B C
Buffers
Messages
1 2 3
- - -
Buffers
Messages
PIDX
(store next)
GIDX
(read oldest)
GIDX
(read oldest)
GIDX
(read oldest)
PIDX
(store next)
PIDX
(store next)
• PIDX incremented last
• Next received message
will be stored into buffer 1
• If buffer 1 has not been read
before message A is lost