SPRUHM8K December 2013 – May 2024 F28377D-SEP , TMS320F28374D , TMS320F28375D , TMS320F28376D , TMS320F28377D , TMS320F28377D-EP , TMS320F28377D-Q1 , TMS320F28378D , TMS320F28379D , TMS320F28379D-Q1
According to the CAN specification, the Bit time is divided into four segments (see Figure 22-14):
Figure 22-14 Bit TimingEach 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 22-4 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 |