SPRUIN7C March 2020 – March 2024 TMS320F280021 , TMS320F280021-Q1 , TMS320F280023 , TMS320F280023-Q1 , TMS320F280023C , TMS320F280025 , TMS320F280025-Q1 , TMS320F280025C , TMS320F280025C-Q1
According to the CAN specification, the Bit time is divided into four segments (see Figure 21-14):
Each segment consists of a specific number of time quanta. The length of one time quantum (tq), which is the basic time unit of the bit time, is given by the CAN_CLK and the Baud Rate Prescalers (BRPE and BRP). With these two Baud Rate Prescalers combined, divider values from 1 to 1024 can be programmed:
Apart from the fixed length of the synchronization segment, these numbers are programmable. Table 21-4 describes the minimum programmable ranges required by the CAN protocol.
A given bit rate can be met by different bit time configurations.
Parameter | Range | Remark |
---|---|---|
Sync_Seg | 1 tq (fixed) | Synchronization of bus input to CAN_CLK |
Prop_Seg | [1 … 8] tq | Compensates for the physical delay times |
Phase_Seg1 | [1 … 8] tq | Can be lengthened temporarily by synchronization |
Phase_Seg2 | [1 … 8] tq | Can be shortened temporarily by synchronization |
Synchronization Jump Width (SJW) | [1 … 4] tq | Cannot be longer than either phase buffer segment |