CAN Communication Blocks

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Overview

The CAN (Controller Area Network) block family enables robust, multi-master communication on CAN bus networks. CAN is widely used in automotive, industrial automation, and embedded systems for reliable data exchange in electrically noisy environments.

The MCHP Blockset provides three blocks for CAN communication: CAN Config for peripheral setup, CAN Tx for message transmission, and CAN Rx for message reception with flexible filtering. These blocks support both CAN 2.0 (standard) and CAN-FD (flexible data-rate) protocols.

CAN Protocol Features

• Multi-master architecture: Any node can initiate communication
• Message prioritization: Lower IDs have higher priority (automatic arbitration)
• Error detection: CRC, ACK, frame check, bit monitoring, bit stuffing
• Fault confinement: Automatic bus-off recovery and error counting
• Deterministic: Guaranteed message latency based on priority
• Flexible data rates: CAN 2.0 up to 1 Mbps, CAN-FD up to 8 Mbps (data phase)

Available Blocks

CAN Config

Configures the CAN peripheral including bit timing (baud rate), message buffer allocation, and pin assignments. This block is required before using CAN Tx or CAN Rx blocks.

Key Parameters:

• Baud rate (50 kbps to 1 Mbps)
• Bit timing (auto-calculated)
• CAN-FD support (SAM devices)
• Buffer allocation (auto-configured) [View Documentation →]

CAN Tx

Transmits CAN messages on the bus with configurable ID, data length, and priority. Supports standard (11-bit) and extended (29-bit) identifiers, RTR frames, and both FIFO and buffer modes.

Key Parameters:

• Message ID (standard/extended)
• Data size (0-8 bytes CAN, 0-64 bytes CAN-FD)
• Transmission mode (FIFO/buffer)
• RTR support [View Documentation →]

CAN Rx

Receives CAN messages with flexible filtering options. Supports exact match, range, and mask-based filters for both standard and extended IDs. Configurable storage in FIFOs or dedicated buffers.

Key Parameters:

• Filter type (classic/dual/range)
• Message ID and mask
• Buffer mode (FIFO/dedicated)
• Data size configuration [View Documentation →]

Block Selection Guide

When to Use Each Block

Device Family Support

Typical CAN Network Example

CAN Network Topology (250 kbps):

┌─────────────┐         ┌─────────────┐         ┌─────────────┐
│  Master ECU │         │ Motor Node  │         │ Sensor Node │
│             │         │             │         │             │
│ CAN Config  │         │ CAN Config  │         │ CAN Config  │
│ CAN Tx      │         │ CAN Rx      │         │ CAN Tx      │
│ CAN Rx      │         │ CAN Tx      │         │ CAN Rx      │
└─────┬───────┘         └─────┬───────┘         └─────┬───────┘
      │                       │                       │
    ──┴───────────────────────┴───────────────────────┴──
      CAN_H ────────────────────────────────────────────
      CAN_L ────────────────────────────────────────────
      │                                                 │
    [120Ω]                                           [120Ω]
    Termination                                   Termination

Message Flow:
  Master → All:    ID 0x000 (broadcast commands)
  Master → Motor:  ID 0x100 (speed setpoint)
  Motor → Master:  ID 0x200 (status feedback)
  Sensor → All:    ID 0x300 (sensor data)

Priority Order (Lower ID = Higher Priority):
  0x000: Highest (emergency broadcast)
  0x100: High (motor control)
  0x200: Medium (status)
  0x300: Lower (sensor data)

CAN vs CAN-FD Comparison

Getting Started

Quick Setup (3 Steps)

• Add CAN Config Block

• Drag from MCHP Blockset → BUS CAN → CAN_Config

• Select CAN module (CAN0/CAN1/MCAN0/MCAN1)

• Choose baud rate (e.g., 250000 for 250 kbps)

• Assign RX/TX pins

• Add CAN Tx Block (Optional)

• Drag from MCHP Blockset → BUS CAN → CAN_Tx

• Set message ID (e.g., 0x100)

• Configure data size (e.g., 8 bytes)

• Connect MsgLen and Tx data inputs

• Add CAN Rx Block (Optional)

• Drag from MCHP Blockset → BUS CAN → CAN_Rx

• Set message ID and filter (e.g., 0x200, mask 0x7FF)

• Configure data size (e.g., 8 bytes)

• Use MsgID, MsgLen, and Rx data outputs

Best Practice: Start with a simple loopback test (one Tx, one Rx, same ID) to verify CAN peripheral configuration before building complex networks.

Common Use Cases

1. Motor Control Network

Application: Distributed motor control with central controller

• Master sends speed commands (ID 0x100-0x10F, one per motor)
• Motors respond with status (ID 0x200-0x20F)
• Emergency stop broadcast (ID 0x000)
• Baud rate: 500 kbps, update rate: 100 Hz

2. Sensor Data Acquisition

Application: Multiple sensors reporting to data logger

• Each sensor transmits with unique ID (0x300-0x3FF)
• Logger uses range filter (0x300-0x3FF) to receive all
• Timestamp included in message payload
• Baud rate: 250 kbps, periodic transmission (10-50 Hz)

3. Firmware Updates (CAN-FD)

Application: Over-the-air firmware update via CAN-FD

• Update packets with 64-byte payload (ID 0x500)
• Acknowledgment messages (ID 0x501)
• Data phase at 2-5 Mbps for fast transfer
• CRC verification and retry mechanism

Troubleshooting Guide

Related Documentation

• [UART Communication Blocks] - Serial communication alternative
• [SPI Communication Blocks] - High-speed synchronous communication
• [I2C Communication Blocks] - Multi-device bus communication
• [Digital I/O Blocks] - CAN transceiver control

References

• ISO 11898-1:2015 - Road vehicles — Controller area network (CAN)
• Bosch CAN FD Specification Version 1.0
• [SAM E70/S70/V70/V71 Family Datasheet (DS60001527)] - MCAN Peripheral
• [SAM E5x/D5x Family Datasheet (DS60001507)] - CAN Peripheral
• Application Note: CAN Network Design and Best Practices (search [Microchip Portal])
• Application Note: CAN-FD Migration Guide (search [Microchip Portal])

See Also

Datasheets

• SAM E70/S70/V70/V71 Family Datasheet (DS60001527)
• SAM E5x/D5x Family Datasheet (DS60001507)

Other

• Microchip Portal
• Microchip Portal