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XC161 Derivatives
Peripheral Units (Vol. 2 of 2)
TwinCAN Module
User’s Manual
21-34
V2.2, 2004-01
TwinCAN_X1, V2.1
Figure 21-19 Data Frame Transfer in Normal Gateway Mode with a 2 Stage FIFO on
the Destination Side (MMC
<d>
= ‘01x’)
Remote frames, received on the destination side by a FIFO element, cannot be
automatically passed to the source side. Therefore, the SRREN
<d>
control bits,
associated to the FIFO elements on the destination side, have to be cleared in order to
answer incoming remote frames with matching identifiers directly with a data frame.
Buffered transfers of remote requests from the destination to the source side can be
handled by a software routine operating on the FIFO buffered gateway configuration for
data frame transfers. The elements of the FIFO buffer on the destination side should be
configured as transmit message objects with CPUUPD
<d>
= ‘10’. An arriving remote
FIFO
CANPTR<sl>
MMC<sl> = ‘011’
Node = <d>
MCA05489
FSIZE = ‘00001’
CANPTR = <d>
MMC = ‘100’
Node = <s>
DIR = ‘0’
DATA
ID
DLC
TXRQ = ‘10’
RMTPND = ‘01’
NEWDAT = ‘01’
INTPND
Copy by SW if Required
Copy by SW if Required
Set by SW
Reset by SW
Reset by SW
Unchanged
Set if RXIE<d> = ‘1’
Unchanged
Reset by SW
Reset by SW
FSIZE = ‘00001’
CANPTR<ba>
MMC<ba> = ‘010’
Node = <d>
DIR = ‘1’
DATA
ID
DLC
TXRQ = ‘01’
RMTPND = ‘01’
NEWDAT
INTPND
Remote Frame
Data Frame (CPUUPD<d> = ‘01’)
Remote Frame
Copy Remote Request by SW
(CPUUPD<d> = ‘10’)
Gateway
Destination
Gateway
Source
Gateway
Destination CAN Bus
Source CAN Bus
Pointer to
Base
Object
Pointer to next addressed
Destination Message Object