GR712RC-UM, Jun 2017, Version 2.9 140 www.cobham.com/gaisler
GR712RC
18.4.6 Transmit buffer
The table below shows the layout of the transmit buffer. In BasicCAN only standard frame messages
can be transmitted and received (EFF messages on the bus are ignored).
If the RTR bit is set no data bytes will be sent but DLC is still part of the frame and must be specified
according to the requested frame. Note that it is possible to specify a DLC larger than 8 bytes but
should not be done for compatibility reasons. If DLC > 8 still only 8 bytes can be sent.
18.4.7 Receive buffer
The receive buffer on address 20 through 29 is the visible part of the 64 byte RX FIFO. Its layout is
identical to that of the transmit buffer.
18.4.8 Acceptance filter
Messages can be filtered based on their identifiers using the acceptance code and acceptance mask
registers. The top 8 bits of the 11 bit identifier are compared with the acceptance code register only
comparing the bits set to zero in the acceptance mask register. If a match is detected the message is
stored to the fifo.
Table 126.Transmit buffer layout
Addr Name Bits
76543210
10 ID byte 1 ID.10 ID.9 ID.8 ID.7 ID.6 ID.5 ID.4 ID.3
11 ID byte 2 ID.2 ID.1 ID.0 RTR DLC.3 DLC.2 DLC.1 DLC.0
12 TX data 1 TX byte 1
13 TX data 2 TX byte 2
14 TX data 3 TX byte 3
15 TX data 4 TX byte 4
16 TX data 5 TX byte 5
17 TX data 6 TX byte 6
18 TX data 7 TX byte 7
19 TX data 8 TX byte 8
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