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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53 views

Is there really a proper way to send private bits even 1 with CANBUS?

I was thinking of making an authentication protocol for canbus. Is there a way to send even 1bit privately to another node ? Have seen many implementations quite a few good ones. In particular ESA ...
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How to re-initialize CANbus in case of an error at stm32f4 series

I have to set a scan program to re-init canbus in case of errors such as disconnection of Rx-Tx lines, or other errors types. When any error is solved, my program will detect and re-init. But are ...
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Is it possibile to use a CAN transceiver to send RS485 data?

Looking at the signal ranges I'm not sure if I can use a CAN transceiver (not controller!) to send data to a single RS485 device.
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CAN bus malfunction on STM32F3

I create applications for STM32 F303RE for communication with the instrument panel. I managed to connect everything but I have some problems. I'm not sure if it's due to bad code or good performance. ...
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38 views

NAK in CAN bus for STM32F3 uC

I have a problem with the NAK on the CAN bus. On STM32F303RE I wrote a code for communication via CAN bus with car dashboard (Instrument Panel Cluster). The communication works, I manage to receive ...
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How to connect CAN modules of two STM32 evalboards

I have two stm32f407 discovery evalboards and I want to connect them using their CAN modules. Is that possible without any CAN transceiver? It comes to me logical but transceiver convert data ...
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48 views

CAN bus traffic is destroyed for unknown reason

I am a bit stuck with connecting several STM32F405 with BeagleBone black via CAN bus. Strange things happen when I connect 3 stm32 and 1 BB. I have checked that BB works perfectly with any ...
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54 views

Selectable CAN bus split termination

I am designing a CAN device where the user may switch between it being the end device and thus with terminators or vice versa. Now, there is no need to drive it digitally using MCU, I would actually ...
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39 views

Is there hardware compatibility between CAN 2.0 High Speed, Low Speed and CAN-FD?

I am studying CAN interface hardware for the design of an automotive scanner. So far, I have identified the following types of CAN: CAN 2.0 High-Speed: bit rate up to 1Mbps CAN 2.0 Low Speed: bit ...
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CAN Physical layer - Choke evaluation

I have my CAN configuration as shown in the below drawing(automotive application), the uC that I’m using has both the CAN controller and the physical layer transceiver built-in so I don’t need a ...
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63 views

Does the standard termination of 120 ohm really suppress reflections in recessive state in CAN?

Suppose we have a multi-node CAN network with the ends of transmission line terminated with the standard 120 ohm. When the recessive state is on the transmission line, the voltage on both CAN_H and ...
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Some Physical Layers used with OBDII

I need to review some physical layers used in OBDII, a very common interface communication of vehicles and used as interface in a automotive scanners. I don't need exactly to know how the protocol ...
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CAN: Difference between an MCU with CAN embedded peripherals and one that does not?

For example, an MCU (stm32, esp32, Pic18f .. etc) with CAN embedded, sends logic level signals through pins Tx and Rx. They only need a signal converter. (example: MCP2551). My question: Why can't ...
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Using Flat-Flex for CAN connection

I am currently developing a robot with multiple modules that have to be connected using CAN (at 5V or 3.3V). The robot has 2 strong DC motors (with spikes over 100A) and also operates close to ...
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38 views

Necessity of an Inductor at CAN Transceiver end

Basically 120 ohm of resistor needs to be connected as terminator resistor at the end of the physical CAN channel. My question is that here, what is the necessity of an inductor (L310) between CAN ...
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Automatic Baud rate selection in STN2120 logic, i would like to implement in TMS470. So, can someone help for Algorithm

I would like to implement set auto baud rate in TMS470 as like STN2120 or ELM327. ELM327 have a algorithm to select a auto baud rate by itself. can we implement in TMS470MF06607 controller? I want ...
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Microe MCP25625 Click Extra components questions?

I'm trying to implement MCP25625 CAN controller and tranceiver in my design. I checked the dev board of Microe MCP25625 Click and especially in the the lines CANH and CANL like it is showen in the ...
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35 views

Canbus over canberry with raspberry pi two messages together at the same time

Im using a canberry with raspberry pi. Is there any way possible to send two messages at the same time with same id and be received by the other raspberry without any particular chance of getting a ...
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48 views

Sniffing lowspeed CAN bus with highspeed device

Is it possible to use a highspeed (HS) CAN interface for listening to a lowspeed (LS) CAN bus? If so - Is it in any way questionable to do so in a real world car or moped? As far as I know, LS CAN ...
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Interfacing Vector(VN1610) CAN Simulator with an OBD reader (Freematics One+ B)

I am using a Freematics One+ B for my project and to avoid developing and testing in a car, i would like to simulate ODB messages. I already have a Vector CAN emulator (VN1610) which creates proper ...
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29 views

Hooking up a device which is powered externally, to the OBD port of a car

I have a device called AutoPi (https://www.autopi.io) which is simply a Raspberry Pi Zero aggregated with a couple of more components. The device takes it's power from the OBD port. I want to make ...
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36 views

How to check the signal integrity of CAN lines?

Its a general question.I would like to know what to look for when testing CAN circuit on CANH and CANL lines.What are the issues that are common?
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RS232/CAN switch circuit

I am working on a communication switch that is digitally controlled and I am using four MUX506IPWR from TI to choose the output channel. The switch has on the input a DSUB9 for a CAN channel and a ...
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98 views

CAN bus with CANL only?

I'm interfacing a product that operates on a kind of CAN bus. Specifically, it uses the CANL line only. I'd like to use a transceiver I've used before, the MCP2562, and I suspect there's not likely ...
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Can you use a CAN FD transceiver for low speed (fault tolerant) CAN?

Fault tolerant CAN (ISO11898-3) is terminated differently than high speed CAN (ISO11898-2). Therefore the signal levels for dominant and especially recessive bits differ. Newer CAN FD compatible ...
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80 views

ATSAMC21 - CAN configuration - Nominal bit timing vs. data bit timing & time quanta calculation

I'm trying to configure the CAN bit rate of an ATSAMC21 to 125ksps in a CAN2.0B configuration. However, after reading through the datasheet, the ASF documentation and the ATMEL start help I'm confused....
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55 views

Custom CAN-FD PCB - what to watch out for?

I'm designing a PCB which will communicate with a vehicle through CAN-FD at up to 2 Mbit/s. The connection to the vehicle is made though ordinary twisted-paid CAN wire (around 2m) to a Mini Universal ...
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111 views

Canbus, Opencan and ISO BUS

Quick question, I know about CanBus protocol. I'm interesting about ISOBUS and CanOpen. I ...
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75 views

Selection criteria for microcontroller to read data from a car's CAN bus (from OBD2 to microcontroller)

I want to read data from a car's CAN bus using a micro-controller. The micro-controller is used outside the car (via OBD to micro-controller). A few micro-controllers i found with CAN interfaces are ...
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81 views

MCP25625 SPI MISO Not Responding

As per title, I'm trying to send a simple 'READ' (0x03) command to the device and get the contents of the CANCTRL register (0x0F). I even moved past our project board and bought Microchip's ...
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42 views

Short-circuit in CAN lines

I have a device with a SNx5HVD251 CAN transceiver. I opened the datashett and read the following parameter: IOS(SS) - Short-circuit steady-state output current Below are two images of the datasheet ...
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107 views

CAN over 12V DC possible?

I was wondering, can I connect the CAN H and CAN L terminals of a MCP2551 or SN65HVD230 transceiver to the 12V and GND to send signals to other devices that are connected the same way? I always ...
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61 views

can bus - effects of non-twisted lines

I have a vehicle which I have upgraded the AV electronics from a newer model (infiniti G37). To do this, I created an adapter harness that effectively moves the wiring to the new locations. The ...
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40 views

Which parameter to use to specify the relay in a CAN line communication?

I need to use SSRs (solid state relays) to comute lines of comunication to a vehicular OBD-II interface. I will use SSRs to choose wich lines will be used at the pins of the connector. The lines wil ...
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89 views

Estimating CAN Bus Load [duplicate]

It's my first time doing this kind of task, so I'm a little unsecure if my method is right. Heres my setup and what I`ve done so far. I`m using a PCAN USB (Peak System) + PCAN View tracing a J1939 ...
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53 views

Interfacing LIN bus with CAN

On the following figure, LIN is used to build subnetworks from a CAN bus: Is there any standardized way to interface these two buses (e.g. for addressing a LIN node from a CAN node)? I read an ...
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CAN0 confustion in Datasheet for ATSAMC21G uC

I currently narrowing my search for a uC with a CAN controller and a few ADC inputs. One of them is the 'ATSAMC21G' 32bit uC from Microchip. In the datasheet on p.31 is the table of the pin ...
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65 views

Designing a CANbus+DC power network of sensors

I'm designing a network of sensors to be placed in an outdoor environment, see the attached diagram. The network will consist of 30 data acquisition boards (very low power consumption), divided in 10 ...
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38 views

Connecting a CAN node results in infinite errors on the bus

I'm developing a device which is controlled by the received CAN messages. The device should be eventually mounted in a vehicle. The device receives messages only. It doesn't send any messages on the ...
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50 views

CAN BUS Termination Resistors For CAN Logger Device

I am making a CAN logger device that will be connected to the vehicle OBD port. Since the CAN bus inside the vehicle is already terminated, do I need to terminate the BUS lines on my device end, right ...
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96 views

How does a CAN transceiver work?

CAN Transceiver Transmit Mode I try to understand the transmit functionality of a CAN transceiver. I found this post a good starting point, but it doesn't completely answer my question. Block ...
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Transceiver for higher voltage CAN bus?

Recently I have encountered CAN bus where CAN-LOW is about 9V, and CAN-HIGH is about 12.5V, respective to ground. ISO standard is 11992-1. Does anyone know any transceiver that uses these voltages on ...
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107 views

Is it possible to use J1939 and CANOpen on the same bus?

Please correct me if i'm wrong. The way I understand it, J1939 is based on CAN2.0b and uses 29 bit identifiers. CANOpen is based on CAN2.0a and uses 11 bit identifiers. If for example, you have a ...
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60 views

How to connect a few shields correctly?

There are several shields on my PCB: shield on CAN-bus, on RS485, on Ethernet, on ENCODER motor signals. How do I correctly connect all these shields? If I use the star topology, which filters should ...
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66 views

CAN Bus multidirectional

I am currently looking for a uC for a project of mine which needs a CAN interface. This would be my first project using CAN. Since I want to send and receive messages between the master and at least 8 ...
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109 views

Sending a double type value over CAN Bus

I need help to send a double value using a CAN Bus. I am working on a eletronic traction control and i need to send, by a CAN bus, the calculated values of speed of wheels. The problem start when the ...
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51 views

Why CAN bus impedence changes when I send data?

I have setup two chanels to send data from PC to micrcontroller. Both of them were working initially. Now one of the chanel does not work. WHen I dont send any data, Impedence between Can-H and Can-L ...
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72 views

Configuring UART TX and RX pins to accept CAN TX and RX signals

The microprocessor I'm using, the BeagleBone Black, has an option to send CAN messages to/from it through the UART Tx and Rx pins. I'm not sure, though, if this is a 1:1 translation (i.e. the UART TX ...
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163 views

Ethernet vs CAN bus physical signal

Reading about Controller Area Networks and Ethernet standard, I cannot understand why there is a difference in the way the signal is transmitted. Both protocols use twisted pair cables to communicate, ...
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123 views

CAN bus split termination impedance - no 60 ohm resistors?

Typical CAN Bus termination involves a 120Ω resistor between CANH and CAHL. To go further than this, I've read that the 120Ω resistance can be split into two 60 ohm resistors with a capacitor in ...

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