--- title: "ESP32-C3 + W5500 + CANbus" url: "https://maker.wiznet.io/Grace_Koo/projects/esp32-c3-w5500-canbus/" markdown_url: "https://maker.wiznet.io/Grace_Koo/projects/esp32-c3-w5500-canbus/md" type: "UCC: User Created Content" author: "Grace" author_url: "https://maker.wiznet.io/Grace_Koo/" original_author: "Grace Koo" original_url: "https://furmwareupdates.com/2025/08/19/esp32-c3-w5500-canbus/" published: "2025-12-31" language: "en" tags: ["MQTT", "ESP32"] hardware: ["WIZnet W5500", "Espressif ESP32"] likes: 0 views: 1140 comments: 0 source: "WIZnet Makers (https://maker.wiznet.io/)" --- # ESP32-C3 + W5500 + CANbus > Bridges CAN bus to MQTT using ESP32-C3 and W5500, enabling remote industrial monitoring and control. Original author: Grace Koo (source: https://furmwareupdates.com/2025/08/19/esp32-c3-w5500-canbus/) ## Components - **WIZnet W5500** x 1 ([docs](https://docs.wiznet.io/Product/Chip/Ethernet/W5500)) - **Espressif ESP32** x 1 ([docs](https://www.espressif.com/en/products/socs/esp32)) WIZnet parts: W5500 ([Datasheet](https://docs.wiznet.io/Product/Chip/Ethernet/W5500/datasheet?utm_source=maker&utm_medium=project&utm_campaign=w5500), [product hub](https://maker.wiznet.io/products/w5500/)) ## Documents and links - [esp32-c3-w5500-canbus](https://furmwareupdates.com/2025/08/19/esp32-c3-w5500-canbus/) (schematics) ## Article *Cover image generated by Gemini.* ## ESP32-C3 + W5500 + CANbus: CAN ↔ MQTT Bridge Board ![](https://furmwareupdates.com/wp-content/uploads/2025/08/Capture-2.jpg) This project combines an **ESP32-C3**, a **W5500 (wired Ethernet)**, and a **CAN transceiver** on a single board, and uses it as a **bridge (gateway) between CANbus and an MQTT broker**. The author states that **ESPHome is used mainly for OTA (firmware update) convenience**, and the data path is built around MQTT. Repository: ```plaintext https://furmwareupdates.com/2025/08/19/esp32-c3-w5500-canbus/ ``` --- #### 2) Why send CAN data over MQTT? CAN and MQTT are used in different environments. - **CAN**: A communication bus used inside machines (vehicles, robots, industrial equipment), where multiple modules share short messages (**ID + data**) quickly and reliably. - **MQTT**: A messaging protocol running on Ethernet/Wi-Fi networks, where devices publish/subscribe through a **broker (server)**. In other words, CAN data usually stays **inside the machine**, while MQTT is a practical way to send data to **servers, dashboards, and storage systems**. That is why a gateway is used: it reads CAN messages and publishes them as MQTT topics, and (if needed) converts MQTT commands back into CAN messages and sends them to the CAN network. --- #### 3) When is this type of gateway useful? - When a CAN-based system already exists in the field and you want to build **monitoring / logging / alarms** on a server - When you need **remote diagnostics** and also want to send **control/configuration commands** - When it is difficult to modify the existing equipment, and you want to extend it by adding **only a gateway in the middle** --- #### 4) Hardware Architecture ![](https://furmwareupdates.com/wp-content/uploads/2025/08/SCH_Schematic1_1-P1_2025-08-19-1024x727.png) - **MCU**: ESP32-C3 - **Ethernet**: W5500 (SPI-based) - **CAN**: CAN transceiver - **Additional**: An RS485 transceiver was added late, but it is not routed to a connector—only test pads are provided (left for future expansion). --- #### 5) How it works (CAN ↔ MQTT) The system is built around a simple flow: “read CAN → publish to MQTT, receive MQTT → send to CAN”. **CAN → MQTT (publish)** When a CAN frame is received, the payload is converted to a HEX string and published to MQTT topics such as: - `canbus/raw/out/` : raw output by CAN ID - `canbus/canopen/out//` : the same data is also published using a CANopen-style categorized topic structure **MQTT → CAN (send)** When JSON is received on `canbus/in`, the firmware parses fields such as `can_id` and `data` (HEX string), builds a CAN frame, and transmits it on the CAN bus. --- #### 6) Network / firmware setup (ESPHome example) - In the shared example configuration, **Wi-Fi is enabled**, and the **W5500 Ethernet configuration is commented out**. - The author separately notes that **wired Ethernet has been tested**. - The CAN configuration is defined by TX/RX pins and bitrate (example: **250 kbps**). --- #### 7) Points to highlight compared to similar projects - The goal is not “CAN testing”, but a clear **CANbus ↔ MQTT broker integration**. - The board includes **wired Ethernet using W5500**, and pin definitions are shown in the configuration (commented). - MQTT output is provided in both **raw** and **CANopen-style categorized** topic formats, which helps downstream systems organize data using topic structure alone. - EasyEDA project files are provided, so there is a clear path for **reproducing / manufacturing** the same design. --- #### 8) Example applications - **Industrial data collection (OT → IT)**: publish CAN status/alarm frames to MQTT for monitoring and log storage - **Remote diagnostics / maintenance**: observe field data via MQTT, and send control frames back via MQTT → CAN when required - **Test / validation environments**: collect CAN messages into a broker to build dashboards, rule engines, or analysis pipelines - **Future expansion**: if RS485 is routed to a connector later, the board can be extended into a combined **CAN + RS485** gateway (current version uses test pads only) --- Source: https://maker.wiznet.io/Grace_Koo/projects/esp32-c3-w5500-canbus/