---
# System prepended metadata

title: CAN-10/5
tags: [electrical_system, 電系組]

---

# CAN #
author: 陳煥宇
date: 2025/10/6


* 參考資料：
[CAN Bus: Serial Communication - How It Works?](https://www.youtube.com/watch?v=JZSCzRT9TTo)
[CAN Bus Explained - A Simple Intro [v2.0 | 2021] 🌟](https://youtu.be/oYps7vT708E)
[【臺大賽車隊】CAN Bus組教學(連結不宜公開)](https://youtu.be/1L_I03t4S6I)
[RS485 CAN HAT](https://www.waveshare.net/wiki/RS485_CAN_HAT#.E6.A0.91.E8.8E.93.E6.B4.BE.E4.BD.BF.E7.94.A8)

* CAN defintion：
Controller Area Network，像車子的中樞神經系統。

* How it works：
兩條 bus 一高一低，利用傳遞訊號， $V_d$ 大為 1，小為 0，如此可消除 common mode，每個 node 可以決定接不接收。![image](https://hackmd.io/_uploads/SycGONlagl.png)


* benefits：
    1. Simple & low cost
    2. Fully Centralized
    3. Extremely robust: can cancel common mode singals, CRC
    4. Efficient: ID with priorities

* properties:
    1. Bus Topology
    2. Half Duplex
    3. Differential
    4. Asynchronous
    5. Serial Signal

* baud rate & CAN frame
    1. 9600 Bd 有效數據訊號調變載波的速率
    2. ![image](https://hackmd.io/_uploads/r1jRcVgTxl.png)
        (1) ID: Priorities
        (2) CRC: Verification code

* decode CAN bus data
    1. little endian -> reorder
    2. hex -> dec
    3. CAN database to convert into physical values

* higher layer protocols
    1. J1939
    2. OBD2
    3. CANopen

* RS485 CAN HAT
    1. CAN bus: Check and verify
    2. RS485: I/O
    3. Important: H-H, L-L![image](https://hackmd.io/_uploads/S18iQrlaeg.png)
