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20.3.11.7 Gateway Mode
The Gateway Mode makes it possible to establish an automatic information transfer
between two independent CAN buses without CPU interaction.
The Gateway Mode operates on message object level. In Gateway mode, information is
transferred between two message objects, resulting in an information transfer between
the two CAN nodes to which the message objects are allocated. A gateway may be
established with any pair of CAN nodes, and there can be as many gateways as there
are message objects available to build the gateway structure.
Gateway Mode is selected by setting MOFCRs.MMC = 0100
object s. The gateway destination object d is selected by the MOFGPRd.CUR pointer of
the source object. The gateway destination object only needs to be valid (its
MSGVAL = 1). All other settings are not relevant for the information transfer from the
source object to the destination object.
Gateway source object behaves as a standard message object with the difference that
some additional actions are performed by the MultiCAN module when a CAN frame has
been received and stored in the source object (see
1. If bit MOFCRs.DLCC is set, the data length code MOFCRs.DLC is copied from the
gateway source object to the gateway destination object.
2. If bit MOFCRs.IDC is set, the identifier MOARs.ID and the identifier extension
MOARs.IDE are copied from the gateway source object to the gateway destination
object.
3. If bit MOFCRs.DATC is set, the data bytes stored in the two data registers
MODATALs and MODATAHs are copied from the gateway source object to the
gateway destination object. All 8 data bytes are copied, even if MOFCRs.DLC
indicates less than 8 data bytes.
4. If bit MOFCRs.GDFS is set, the transmit request flag MOSTATd.TXRQ is set in the
gateway destination object.
5. The
receive
MOSTATd.NEWDAT are set in the gateway destination object.
6. A message interrupt request is generated for the gateway destination object if its
MOSTATd.RXIE is set.
7. The current object pointer MOFGPRs.CUR of the gateway source object is moved to
the next destination object according to the FIFO rules as described on
A gateway with a single (static) destination object is obtained by setting
MOFGPRs.TOP = MOFGPRs.BOT = MOFGPRs.CUR = destination object.
The link from the gateway source object to the gateway destination object works in the
same way as the link from a FIFO base to a FIFO slave. This means that a gateway with
an integrated destination FIFO may be created; in
the gateway source object and the message object on the right side is the gateway
destination objects.
User's Manual
MultiCAN, V2.24
Controller Area Network Controller (MultiCAN)
pending
bit
MOSTATd.RXPND
Figure
20-21):
and
Figure
20-20, the object on the left is
20-53
TC1728
for the gateway source
B
the
new
data
Page
V1.0, 2011-12
bit
20-49.
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