User`s guide

LF2407 eZdsp
3-58
• DSPChip
- CAN — Parameters that affect the control area network (CAN) module.
Most of these parameters affect the CAN bit timing. The CAN protocol
divides the nominal bit time into four segments, which are reflected in the
settable parameters below. The four segments are
SYNCSEG — Time used to synchronize the nodes on the bus. It is always
one time quantum (TQ), which is defined as
where SYSCLK is the CAN module system clock frequency, and the
BitRatePrescaler is defined below.
PROP_SEG — Time used to compensate for the physical delays in the
network
PHASE_SEG1 — Phase used to compensate for positive edge phase error
PHASE_SEG2 — Phase used to compensate for negative edge phase error
The settable parameters are
BitRatePrescaler — Value by which to scale the bit rate. Valid values are
from 1 to 256. As noted in the equation above, this value determines the
value of TQ.
SAM — Number of samples used by the CAN module to determine the
CAN bus level. Selecting
Sample_one_time samples once at the sampling
point. Selecting
Sample_three_times samples once at the sampling point
TQ
1
SYSCLK
--------------------------
BitRatePrescalar 1+()⋅=