Renesas M32R/ECU Series User Manual page 549

13
13.1 Outline of the CAN Module
The 32180 contains two-channel Full CAN modules compliant with CAN (Controller Area Network) Specification
V2.0 B Active. These CAN modules each have 16 message slots and three mask registers, effective use of which
helps to reduce the data processing load of the CPU.
The CAN modules are outlined below.
Table 13.1.1 Outline of the CAN Module
Item
Protocol
Number of message slots
Polarity
Acceptance filter
(Function to receive only a range
of IDs specified by receive ID filter)
Baud rate
Remote frame automatic
response function
Timestamp function
BasicCAN mode
Transmit abort function
Loopback function
Return bus off function
Single shot function
DMA transfer function
Self-diagnostic function
Note 1: The maximum allowable error of oscillation depends on the system configuration (e.g., bus length, clock error, CAN
bus transceiver, sampling position and bit configuration).
Table 13.1.2 DMA Transfer Requests Generated by CAN
DMA Transfer Request by CAN
CAN0: Slot 0 transmission failed or slot 15 transmit/receive operation finished
CAN1: Slot 1 transmission failed or slot 14 transmit/receive operation finished
Description
CAN Specification V2.0 B Active
Total 16 slots (14 global slots, two local slots)
0: Dominant
1: Recessive
Global mask: 1
Local mask: 2
1 time quantum (Tq) = (BRP + 1) / (CPU clock/2)
(BRP: Baud Rate Prescaler set value)
Baud rate =
Tq period × number of Tq's for one bit
BRP: 1–55 (0: inhibited)
Number of Tq's for one bit = Synchronization Segment + Propagation Segment
Propagation Segment: 1–8Tq
Phase Segment 1: 1–8Tq
Phase Segment 2: 1–8Tq (IPT = "1")
The slot that received a remote frame responds by automatically sending a data frame.
This function is implemented using a 16-bit counter. The count period is derived from the
CAN bus bit period by dividing it by 1, 2, 3 or 4.
BasicCAN function is materialized using two local slots.
Transmit requests can be canceled.
The CAN module receives the data transmitted by itself.
Error active mode is forcibly entered into after clearing the error counter.
Transmission is not retried even when it failed due to arbitration-lost or a transmit error.
DMA transfer request is generated when transmission failed or transmit/receive operation
finished (CAN0 only).
Communication module is diagnosed by communicating internally in the CAN module.
13-2
13.1 Outline of the CAN Module
1
..... Max 1 Mbps (Note 1)
+ Phase Segment 1 + Phase Segment 2
DMAC Input Channel
DMA0
DMA2
32180 Group User's Manual (Rev.1.0)
CAN MODULE