Specifications

Message Objects
10-16
Figure 10–8. Remote Frame Requests
Transmit mailbox
(AAM = 1)
Transmit mailbox
(AAM = 0)
Transmit mailbox
Receive mailbox
Receive mailbox
Receive mailbox
Situation at mailbox: Setting of corresponding flags:
TRS = 1, TA = 1
(not received)
RMP = 1
RFP = 1, RMP = 1
TRS = 0, TA remains 0,
no mailbox interrupt asserted
The answer is received in this receive mailbox if permitted or in a mailbox of anoth-
er CAN module if it is configured for this frame
The receive mailbox contains the ID, RTR, DLC, and TRS of this mailbox (2 or 3) = 1.
The answer is received in this receive mailbox, if permitted, or in a mailbox of another
CAN module if it is configured for this frame.
remote frame (RTR = 1)
data frame
remote frame (RTR = 1)
remote frame (RTR = 1)
data frame
remote frame (RTR = 1)
remote frame (RTR = 1)
CPU handles situation
(D)
(A)
(B)
(C)
(E)
(F)
10.3.7 Acceptance Filter
The identifier of the incoming message is first compared to the message identi-
fier of the receive mailbox (which is stored in the mailbox in MSGIDnH and
MSGIDnL registers). Then the appropriate acceptance mask is used to mask
out the bits of the identifier that should not be compared. The local acceptance
mask can be disabled by setting the acceptance mask enable (AME) bit to 0
in the message identifier high word (MSGIDn) field.
Local Acceptance Mask (LAM)
The local acceptance filtering allows the user to locally mask (that is, treat as
a don’t care ) any identifier bit of the incoming message.
Local acceptance mask register LAM1 is used for mailboxes 2 and 3 while lo-
cal acceptance mask register LAM0 is used for mailboxes 0 and 1. During a