Datasheet

Figure 20-9. Overload frame.
Ident "A" Cmd Message Data "A" CRC InterframeA Ident "B"
Overload Frame
Overload Frame
RXCDAN
Setting OVRQ bit
OVFG bit
Resetting OVRQ bit
TXCDAN
OVRQ bit
Instructions
20.6. Message objects
The MOb is a CAN frame descriptor. It contains all information to handle a CAN frame. This means that a
MOb has been outlined to allow to describe a CAN message like an object. The set of MObs is the front
end part of the “mailbox” where the messages to send and/or to receive are pre-defined as well as
possible to decrease the work load of the software.
The MObs are independent but priority is given to the lower one in case of multi matching. The operating
modes are:
• Disabled mode
• Transmit mode
• Receive mode
• Automatic reply
• Frame buffer receive mode
20.6.1. Number of MObs
This device has six MObs, they are numbered from 0 up to 5 (i = 5).
20.6.2. Operating modes
There is no default mode after RESET.
Every MOb has its own fields to control the operating mode. Before enabling the CAN peripheral, each
MOb must be configured (ex: disabled mode - CONMOB=00).
Table 20-1. MOb configuration.
MOb configuration Reply valid RTR tag Operating mode
0 0 x x Disabled
0 1 x 0 Tx data frame
x 1 Tx remote frame
1 0 x 0 Rx data frame
0 1 Rx remote frame
1 Rx remote frame then, Tx data frame (reply)
1 1 x x Frame Buffer Receive mode
20.6.2.1. Disabled
In this mode, the MOb is “free”.
Atmel ATmega16M1/32M1/64M1 [DATASHEET]
Atmel-8209F-ATmega16M1/32M1/64M1_Datasheet_Complete-10/2016
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