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initialization mode.
Message receiving and transmitting is disabled in initialization mode.
Normal mode
Clear the INITREQ bit of the configuration register CAN_MCTRL through
software to request to enter the normal mode from the initialization mode; wait
for the hardware to clear the INITFLG bit to enter the normal mode.
Message receiving and transmitting is allowed in normal mode.
Sleep mode
Set the SLEEPREQ bit of the configuration register CAN_MCTRL to 1 to
request to enter the sleep mode.
The clock of CAN stops work in sleep mode, the software can normally access
the mailbox register, and the CAN is in low-power state.
Communication mode
There are four communication modes: silent mode, loopback mode, silent
loopback mode and normal mode. Different communication modes can be
selected only in initialization mode.
Silent mode
Set the SILMEN bit of the configuration register CAN_BITTIM to 1 and select
the silent mode.
In this mode, only recessive bit (logic 1) can be sent to the bus, while the
dominant bit (logic 0) cannot be sent, and the data can be received from the
bus.
Figure 107 CAN Works in Silent Mode
TX
RX
MCU
=1
CANTX
CANRX
Loopback mode
Set the LBKMEN bit of the configuration register CAN_BITTIM to 1 and select
the loopback mode.