STM32F103 can learning record

CAN send data

Data writing Mailbox 0~3 => Send controller => CAN Bus .
Standard library function sending process ： Judge which of the three mailboxes is empty ,CAN1->TSR Medium TME0,TME1,TIM2, Configure sending after judgment .
mailbox 0~3 Send priority ：CAN Protocol frame ID or FIFO Determine mailbox priority , CAN_MCR->TXFP Select priority mode .

CAN receive data

CAN Bus => Filter => Mailbox 0~3 (FIFO) => Program read
stm32f103 Of CAN Yes 2 individual FIFO,14 individual Filter,Filter Configurable to send data to FIFO0 or FIFO1, then FIFO0 or FIFO1 Generate interrupt events . The data has to go through Filter To get to FIFO.

CAN Protocol frame ID

A standard format ：11 position 0x7FF
Extended format ：29 position 0x1FFFFFFF
CAN Control will read while sending data CAN Level state of the bus , Judge whether the transmission is correct by comparing the transmission level with the reception level , And determine the priority of the protocol frame .

Priority on the bus

analogy ：
level 1 It is pulled up by resistance , level 0 It's through NPN From the triode ,0 Will overwrite 1.
Output 0 Time conduction NPN, Output 1 Turn off NPN.
When 2 individual CAN The controller sends 1, Another hair 0 when ,0 Will overwrite 1.
CAN The controller compares the output level with the received level to judge the priority and judge the bus fault .
amount to stm32 Pin OD Output .