50.9.14 CAN Message Mode Register
This register can only be written if the WPEN bit is cleared in the CAN Write Protection Mode Register.
| Name: | CAN_MMRx |
| Offset: | 0x0200 + x*0x20 [x=0..7] |
| Reset: | 0x00000000 |
| Property: | Read/Write |
| Bit | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | |
| MOT[2:0] | |||||||||
| Access | R/W | R/W | R/W | ||||||
| Reset | 0 | 0 | 0 | ||||||
| Bit | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | |
| PRIOR[3:0] | |||||||||
| Access | R/W | R/W | R/W | R/W | |||||
| Reset | 0 | 0 | 0 | 0 | |||||
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| MTIMEMARK[15:8] | |||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W | |
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| MTIMEMARK[7:0] | |||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W | |
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Bits 26:24 – MOT[2:0] Mailbox Object Type
This field allows the user to define the type of the mailbox. All mailboxes are independently configurable. Five different types are possible for each mailbox.
| Value | Name | Description |
|---|---|---|
| 0 | MB_DISABLED | The mailbox is disabled. This prevents receiving or transmitting any messages with this mailbox. |
| 1 | MB_RX | Reception mailbox. The mailbox is configured for reception. If a message is received while the mailbox data register is full, it is discarded. |
| 2 | MB_RX_OVERWRITE | Reception mailbox with overwrite. The mailbox is configured for reception. If a message is received while the mailbox is full, it overwrites the previous message. |
| 3 | MB_TX | Transmit mailbox. The mailbox is configured for transmission. |
| 4 | MB_CONSUMER | Consumer mailbox. The mailbox is configured for reception but behaves like a transmit mailbox, i.e., it sends a remote frame and waits for an answer. |
| 5 | MB_PRODUCER | Producer mailbox. The mailbox is configured for transmission but also behaves like a reception mailbox, i.e., it waits to receive a remote frame before sending its content. |
| 6 | – | Reserved |
Bits 19:16 – PRIOR[3:0] Mailbox Priority
This field has no effect in Receive and Receive with Overwrite modes. In these modes, the mailbox with the lowest number is serviced first.
When several mailboxes try to transmit a message at the same time, the mailbox with the highest priority is serviced first. If several mailboxes have the same priority, the mailbox with the lowest number is serviced first (i.e., MBx0 is serviced before MBx 15 if they have the same priority).
Bits 15:0 – MTIMEMARK[15:0] Mailbox Timemark
This field is active in Time-triggered mode. Transmit operations are allowed when the internal timer counter reaches the Mailbox Timemark. See Transmitting within a Time Window.
In Timestamp mode, MTIMEMARK is set to 0.