TMPR3916 datasheet(131/225 Pages) TOSHIBA

131 / 225 page

Chapter 7 CAN Module (TXCAN)

Preliminary

7-10

7.2.4

Message Reception

The identifier of each incoming message is compared to the identifiers held in the receive mailboxes.

The comparison of the identifiers depends on the value of the global/local acceptance mask enable bit

(GAME/LAME) stored in the mailbox and the data held in the global/local acceptance mask

(GAM/LAM). When a matching identifier is detected, the received identifier, the control bits and the

data bytes are written into the matching RAM location. At the same time the corresponding receive

message pending bit RMPn is set and a receive-interrupt is generated, if it is enabled. After finding a

matching identifier, no further compare will be done. If no match is detected, the message is rejected.

The RMP bit has to be reset by the MCU after reading the data. If a second message has been received

for this mailbox and the RMP bit is already set, the corresponding message lost bit (RML) is set. In this

case, the stored message will be overwritten with the new data.

Only if an incoming message does not match to one of the mailboxes 0 to 14, this message will be

stored in the receive-only mailbox in case of a matching identifier (acceptance filter).

The following figure shows the timing of the flags and the write to the mailbox during message

reception:

Message 1

for mailbox “n”

CAN Bus

Message is valid

Set RMP

Set RML

Copy ID and data

to mailbox

RMPn register

RMLn register

Message 2

for mailbox “n”

Figure 7.2.2 Timing for Writing Received Message to Mailbox, Including Flags

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