MEGA128CAN Datasheet, PDF (238/413 Pages) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

Rx Data & Remote Frame
Automatic Reply
Frame Buffer Receive Mode
– Remote transmission request (RTRTAG)
– Data length code (DLC)
– Reserved bit(s) tag (RBnTAG)
– Data bytes of message (MSG)
2. The MOb is ready to send a data or a remote frame when the MOb configuration is
set (CONMOB).
3. Then, the CAN channel scans all the MObs in Tx configuration, finds the MOb hav-
ing the highest priority and tries to send it.
4. When the transmission is completed the TXOK flag is set (interrupt).
5. All the parameters and data are available in the MOb until a new initialization.
1. Several fields must be initialized before receiving:
– Identifier tag (IDT)
– Identifier mask (IDMSK)
– Identifier extension (IDE)
– Identifier extension mask (IDEMSK)
– Remote transmission request (RTRTAG)
– Remote transmission request mask (RTRMSK)
– Data length code (DLC)
– Reserved bit(s) tag (RBnTAG)
2. The MOb is ready to receive a data or a remote frame when the MOb configuration
is set (CONMOB).
3. When a frame identifier is received on CAN network, the CAN channel scans all the
MObs in receive mode, tries to find the MOb having the highest priority which is
matching.
4. On a hit, the IDT, the IDE and the DLC of the matched MOb are updated from the
incoming (frame) values.
5. Once the reception is completed, the data bytes of the received message are stored
(not for remote frame) in the data buffer of the matched MOb and the RXOK flag is
set (interrupt).
6. All the parameters and data are available in the MOb until a new initialization.
A reply (data frame) to a remote frame can be automatically sent after reception of the
expected remote frame.
1. Several fields must be initialized before receiving the remote frame:
– (c.f. Section “Rx Data & Remote Frame”)
2. When a remote frame matches, automatically the RTRTAG and the reply valid bit
(RPLV) are reset. No flag (or interrupt) is set at this time. Since the CAN data buffer
has not been used by the incoming remote frame, the MOb is then ready to be in
transmit mode without any more setting. The IDT, the IDE, the other tags and the
DLC of the received remote frame are used for the reply.
3. When the transmission of the reply is completed the TXOK flag is set (interrupt).
4. All the parameters and data are available in the MOb until a new initialization.
This mode is useful to receive multi frames. The priority between MObs offers a man-
agement for these incoming frames. One set MObs (including non-consecutive MObs)
is created when the MObs are set in this mode. Due to the mode setting, only one set is
possible. A frame buffer completed flag (or interrupt) - BXOK - will rise only when all the
MObs of the set will have received their dedicated CAN frame.
238 AT90CAN128
4250E–CAN–12/04