CAN FD

CAN FD (Controller Area Network Flexible Data-Rate) is the high-performance evolution of the classical CAN bus. It was developed to meet the growing demand for higher bandwidth in modern vehicles and industrial automation.

CAN FD (控制器區域網路靈活數據速率) 是傳統 CAN 總線的高性能演進版本。它的開發是為了滿足現代車輛和工業自動化對更高頻寬日益增長的需求。

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Key Differences: CAN vs. CAN FD | 主要差異：CAN 與 CAN FD

As requested, here is a comparison of the two standards using metric-friendly terminology:

根據您的要求，以下是這兩種標準的比較表：

Feature 特性	Classical CAN 傳統 CAN	CAN FD
Data Payload 數據負載	Up to 8 bytes	Up to 64 bytes
Max Speed 最大速度	1 Mbps	5 to 8 Mbps (in data phase)
Topology 拓撲結構	Multi-master (Linear)	Multi-master (Linear)
Backward Compatibility 向後相容性	N/A	CAN FD nodes can read Classical CAN
Efficiency 效率	Lower (high overhead)	Higher (more data per frame)

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Why use CAN FD? | 為什麼要使用 CAN FD？

1. Increased Bandwidth (頻寬增加): By increasing the bit rate during the "data phase" and extending the payload from 8 to 64 bytes, it can transmit significantly more data without increasing the physical wiring.

   透過在「數據階段」提高位元速率並將負載從 8 位元組擴展到 64 位元組，它可以在不增加實體佈線的情況下傳輸更多數據。

2. Reduced Latency (降低延遲): Larger frames mean fewer messages are needed to send long data streams, reducing the "wait time" on the bus.

   更大的數據幀意味著發送長數據流所需的訊息更少，從而減少了總線上的「等待時間」。

3. Future-Proofing (面向未來): Essential for modern automotive features like ADAS (Advanced Driver Assistance Systems) and firmware-over-the-air (FOTA) updates.

   對於自動駕駛輔助系統 (ADAS) 和韌體雲端更新 (FOTA) 等現代汽車功能至關重要。

Technical Note | 技術筆記

In a CAN FD frame, the speed increases only during the Data Phase. The Arbitration Phase (where nodes decide who speaks first) still runs at the standard speed (usually 500 kbps or 1 Mbps) to ensure stability across the cable length.

在 CAN FD 幀中，速度僅在數據階段增加。仲裁階段（節點決定誰先發言）仍以標準速度（通常為 500 kbps 或 1 Mbps）運行，以確保整個電纜長度的穩定性。

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