Questions tagged [can]

CAN stands for Controller Area Network and is a bus often used in automotive applications. It is a two-wire differential protocol and works on baud rates from 10 kbits/sec to 1 Mbits/sec.

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CANBUS multi-node communication fails when electing bus master

I'm managing a legacy system (created by my predecessors) which uses CANBUS. In the system there are multiple nodes, which are run by the MC9S08DZ60 microcontroller each. There are of course separate ...
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CAN bus sensors

I want to replace a broken CAN bus sensor with a new one. How can I do it? I don't have node ID of the broken sensor. Is there a way I can find the node ID of previous sensor? It's an angle sensor (...
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CAN-BUS line goes bus off state at high temperature(70C°)

I have a CAN-BUS line communicating at 50kb/s speed. There are only 2 products communicating with each other on the CAN-BUS line. One of these products has the STM32L496RGT MCU (the clock speed of the ...
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51 views

How can a remote oximeter meet the standards of EMC?

An oximeter is a sensor commonly used in medical applications where one needs to retrieve the oxygen saturation of a patient. The reference MAX86141 from Maxim Integrated is one of them : https://www....
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CAN bus stuff error causes due to physical layer

I'm trying to diagnose the significant amount of bus "stuff errors" on my CAN network. Network is new and has not ran without these errors. Topology is as shown below. 18 Devices on CAN bus....
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CAN Bus with RS485 CAN HAT for Raspberry PI

I have set up a CAN bus between 2 STM32 Nucleo's, where one is only sending messages and the other one is only reading them. This works, I have also validated this by connecting them to another CAN ...
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46 views

How to “clean” a DC brushed motor : noise on CANbus even without moving!

We have very odd problem with a DC brushed geared motor that we are driving with a classical H-bridge chopper (20kHz PWM at the moment). The motor kinda looks like a Mabuchi from an R/C car but with ...
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CAN Stub node termination in a network - 9.28k resistor

In a CAN network, the ends of the network has to be terminated with 120 ohm - I understand this. The middle node in the below diagram is the stub node and it does not have to be terminated, my stub ...
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How to find the right components for the CAN bus signals merging?

I have 2 CAN connectors from 2 different devices and I want to design something that takes in both the inputs and gives the output on a single connector. In other words, I want to combine 2 different ...
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43 views

Use “basic CAN” if “full CAN” is available?

From all I've read about both types my conclusion is that the only reason for using "Basic CAN" is to make message handling easier: I have to care about only one buffer. One big drawback is ...
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62 views

Bus communication scheme for large number of devices (255+ nodes)?

I'm trying to figure out the feasibility of setting up some type of differential bus communication for up to 400 devices outdoors. The main constraints are mainly power consumption, complexity, wire ...
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51 views

Grounding in CAN / RS485 Busses

I'm interested in how to properly realize Grounding in a CAN / RS 485 bus setup. From my understanding, when non-isolated transceivers are used, in addition to the differential signal lines, a third ...
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Can-Bus blocked

I have a STM32F105 DevBoard which I implemented on it a simple code to receive frames from the can-bus The problem is on some can-bus lines it does receive the frames but on other lines when the can-...
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UDS vs XCP (Diagnostic)

When performing a calibration or a diagnosis acquisition from an ECU using a CAN-bus is there a protocol preferred? I've come across UDS and XCP but I can't quite get why one might be preferred over ...
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32 views

Cause of delay in CAN

I am dealing with a differential drive robot that interacts with several motors and actuators, all through a powerful NVIDIA Jetson Xavier. The Jetson runs Ubuntu and I use Python3 for programming all ...
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38 views

How to ensure all nodes on CAN bus have received the message

I know that that the ACK bit will be driven by the receiver of the CAN message. I'm wondering what would the situation be if you have multiple nodes listening to the same message. How would you ...
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60 views

Simplify this CAN to CAN transceiver circuit?

I currently have a circuit that does this, is there a way to simplify this circuit, ossibly with isolation? Do I need the BJTs? or can I just connect RX to TX and TX to RX then have a CAN to CAN bus ...
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59 views

STM32 CAN Interrupt causes program to jump in infinite loop

Struggling with this issue for days now and can't find a solution. Maybe someone saw something like this before and can give me a hint. I have FreeRTOS running on an STM32L4 with different tasks. One ...
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Sharing Isolated Power supply for CAN and RS485

I am using ISO1432 from TI for isolated RS485 transceiver function. And ISO1042 for Isolated CAN transceiver. Both devices requires an isolated supply on bus side. Can I use one isolated 5V DC-DC ...
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Configuring UART pins on Beaglebone Black for CAN Interface

I have been using a CAN/RS485 Cape for prototyping CAN control of a motor. I am now in the process of bringing up some custom hardware. I have a CAN Transceiver SN65HVD230D on this custom cape that is ...
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52 views

Separate CAN messages having same ID in function of data content

I am working with some temperature and pressure sensors. These sensors send the messages to a receiver connected with Dewesoft Sirius. In this way I can read the CAN messages on my laptop. The problem ...
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1answer
70 views

Address-free communications between microcontrollers in any topology

Suppose I have 9 microcontrollers each on their own PCB, connected in a square grid. Is there a way I can get a single node to communicate to all the other nodes, be able to address them individually, ...
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103 views

What is the name of this wire-piercing probe?

I'm looking to get can bus data without cutting the wires. I would like to know the name of the probe pictured below and where to find it.
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RS485 over CAN: when and why?

I'm designing my own home automation gateway and I've already added a rs485 transceiver, everything is fine, but I'm thinking about adding also a CAN bus transceiver because I've seen that it's often ...
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Connecting Can Bus Debugger with Arduino Uno

I'm currently trying to interface USB Peak Can with Spark fun can bus shield. So I'm trying to test sending data from the Shield to the USB Peak Can bus, but nothing is sent at all, the same for ...
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61 views

2 devices with different CAN baud

I have a project where I need to talk with 2 devices x & y with 125kbps and 500kbps CAN speeds respectively. So I selected an MCU (F446RC) with 2 CAN controllers from ST. The BOM cost went up and ...
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Designing a universal CAN bus interface

I'm tasked to work for several car manufacturers and would like a system that can work with 'every' car. For example, I bought the peak system CAN Bus usb, and tried it for Kia e Niro and it didn't ...
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CAN Frame Malforming on Oscilloscope

I have a working 500kbps CAN bus between an Arduino Uno and a RaspberryPi. Both are connected to MCP2515/TJA1050 boards from Amazon and communicating over SPI. The RaspberryPi dumps the CAN data via ...
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63 views

Electric vehicle instrumentation [closed]

I have converted a vw bus to 112 VDC electric drive (Tesla battery modules 22.5VDC X 5 ea). There is also a 12V system for lights and instruments. The BMS supports SPI and CAN. I have no experience ...
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CAN Bus: Nodes powered by different Potential Sources

There was one similar question asked in 2018 but there was detail lacking. So here goes: I have an engine running J1919 CAN bus about 15m away from an Engine Info display that receives CAN-bus data. ...
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88 views

Distortion in CAN signal

I have a scope connected to my canH line and ground and noticed there is some distortion on the waveform in my setup. Setup: PCAN-USB device (https://www.peak-system.com/produktcd/Pdf/English/PCAN-...
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CAN transceiver interface with two CAN BUSES

I would like to use the NXP TJA1046/TJA1048 dual CAN transceiver to connect to two CAN BUS. I would like to mux the TX1/TX2 and RX1/RX2 and connect them to single TX/RX interface on the MCU. In order ...
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Weird looking last bit in a CAN message

I did my first CAN bus design on a prototype PCB. Now I would like to verify if the CAN transceiver is working OK. So I connect a PC-CAN-USB debugger and my scope on the CAN_HIGH and CAN_LOW signal ...
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If Pointer Extension = 1, what should Pointer become then in J1939 standard - CAN bus

Assume that we have the EEPROM address 647 and we want to read to it. That can be done in J1939-21 CAN bus standard. But the problem I faceing is that if I'm using Pointer Extension = 1, then I can't ...
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244 views

CAN Bus on PCB traces instead of twisted pair cable - points to consider

In order to save cost on the system in one of my current projects (no cables) I would like to eliminate the CAN cable and add traces to the PCB (one pair from left to right to connect the connectors + ...
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What is “Number of occurrences” in DM16 - Binary data transfer at J1939 CAN-bus protocol

After I have send a DM14 memory access with the functionality read. Assume that I'm want to read 646 and 647 address. Then I want to use the lenght = 1, Pointer Type = 1(if I want DM15 message ...
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MCP2551 with STM32 MCU

im learning about the CAN protocol, and bought the transceiver module MCP2551 like this: I made the driver for CAN controller first in loopback mode for debug, im sending the numbers 1,2,3 and 4 with ...
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What is “Pointer” in DM14 at J1939 CAN-bus standard?

What is "Pointer" in DM14 at J1939 CAN-bus standard? Can it be the memory Address[DEC]?
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Which protocol specifies the meaning of each bit in a CAN message?

A lot of books and articles describe the basic idea of CAN (controller area network) and the requirements to the physical layer as well as the data link layer. But I didn't find any description how ...
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CANBus problem with STM32

I am working with CAN Bus on the Nucleo H743ZI2 (STM32), I have set up the times for a clock souce of 10 Mhz, and can baud rate of 1 Mbps. Everything seems to work correctly until the motor is turn on ...
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CAN Bus Nominal Impedance

I understand the reason for choosing a termination resistor of 120 Ohms for the CAN bus to avoid reflections but why was the nominal impedance of the CAN bus cables required to be 120 Ohms by the ISO ...
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Suitable wire protocol for old house burglar alarm

My house and outbuildings have a simple 20 year old burglar alarm with magnetic open/closed, shock sensors and a few PIRs. The main control panel has failed so I was looking to modernise the alarm ...
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65 views

CAN Split Termination Capacitor Calculation

I'm trying to use the split termination on a CAN bus, but I'm a bit confused about the calculation for the split termination capacitor. It is described in Figure 10 in the Texas Instruments app note ...
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NUCLEO H743ZI-2 CAN FD unreliable

I am writing a library to use the CAN Bus on this STM32 board. Physically this board has CAN FD, which is CAN 2.0 compatible. I require a CAN transceiver to connect to the CAN-H and CAN-L lines. I am ...
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44 views

Printed circuit board connector identification

I have a PCB with some connectors and wanted to identify which type there are of. How do the experts approach the problem, to identify the type? For example, the picture below shows a connector, ...
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53 views

Are external data connections considered “unintentional radiation” by the FCC?

Does a device with an external communication port of some kind fall under "intentional radiation" or "unintentional radiation" according to the FCC for testing and certification ...
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Linearizing multi-star network for home automation

I'm designing a communication network for private home automation. My design goals are: Local wrt network changes. That is, changing one part of the network should not require modification of the ...
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CANBUS keypad is not operational after power reset

I have a 6 button keypad from Greyhill. It can CANOPEN enabled and works fine in my CAN network. But, sometimes when we power off the system overnight, and power it back up in the morning, this keypad ...
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Checking CAN Bus load in Vector interfaces

Are there any other ways to check CAN bus load via CANlyzer (other than Statistic window) or CANoe?
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Removing STM32F4xxx based HMI from CANBUS puts the network in BUSHEAVY state

I have a CANBUS with 3 devices on it. A PLC (CAN IO 14+, HAWE), a HMI (Barth DMA-20) and a 6 button CAN enabled button panel (Greyhill). The issue is, when I remove the display from the network (...

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