DevHeads IoT Integration Server•6d ago

Fixing CAN Bus Overload Issues in Multi-Node Sensor Systems Using AVR128DA48 and MCP2515

Hey guys, I previously worked on an automated irrigation system where different sensors (moisture, temperature) spread across large farmland communicate with a central controller over the CAN Bus. Each sensor node is equipped with an AVR128DA48 microcontroller and an MCP2515 CAN controller to relay data about soil conditions to the controller for real-time decision-making. I’ve set up the CAN Bus network and successfully initialized the CAN controller on each sensor node. The sensor data is being collected properly, and I've verified that the SPI communication between the AVR128DA48 and the MCP2515 is working correctly. However, I’m running into an issue when attempting to synchronize the sensor data broadcasts. The issue occurs during message reception on the central controller. While I’m able to send data from individual sensors, the central node fails to synchronize the data streams. The can_recv() function sometimes receives data, but other times it throws an -EBUSY (Bus Busy) error, suggesting the bus is overloaded or not handling multiple messages well. this is my code:

int ret = can_recv(can_dev, &rx_frame, K_MSEC(100));
if (ret == -EBUSY) {
    LOG_ERR("CAN bus busy, could not receive message");
} else if (ret == 0) {
    LOG_INF("Received CAN message with ID: 0x%x", rx_frame.id);
}

int ret = can_recv(can_dev, &rx_frame, K_MSEC(100));
if (ret == -EBUSY) {
    LOG_ERR("CAN bus busy, could not receive message");
} else if (ret == 0) {
    LOG_INF("Received CAN message with ID: 0x%x", rx_frame.id);
}

Error

[00:00:03.005] <ERR> CAN bus busy, could not receive message

[00:00:03.005] <ERR> CAN bus busy, could not receive message

I expected that the can_recv() function should smoothly capture messages from all the sensor nodes, ensuring each node’s data arrives at the controller in real-time without interruption.

3 Replies

Camila_99$$•6d ago

Hii Dtynin! About the -EBUSY error you're seeing, it could definitely be the bus getting a bit overloaded, especially if multiple sensors are trying to send data at the same time… And have you tried introducing a priority or a slight delay between transmissions from each sensor node? That might help prevent the bus from getting congested. Also, maybe tweaking the CAN bus bit timing could help manage the message traffic better. 👍🏻

Dtynin•6d ago

hey @Camila_99$$ thanks for the heads-up, I'd try them out and get back to you on my progress on it.

Renuel Roberts•6d ago

@Dtynin It seems your CAN Bus network is experiencing contention, where multiple sensor nodes may be transmitting at the same time, leading to the -EBUSY (Bus Busy) error. To resolve this, prioritize messages by CAN ID, check the bus load, adjust the reception timeout, and implement flow control to prevent message collisions. Make sure the bus has proper termination resistors and handle retries in your code for -EBUSY errors. Using a CAN analyzer can help identify any specific bus issues causing these errors.

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Fixing CAN Bus Overload Issues in Multi-Node Sensor Systems Using AVR128DA48 and MCP2515