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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Reading different CAN bus protocols with one interface
We have a system with multiple CAN bus protocols. All are running at 250 kbit/s. These are NMEA 2000, J1939, and CANopen. These systems do not have to communicate with each other, but I would like to ...
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PCB of a CAN bus hub?
I am thinking of making a CAN "hub" PCB. The PCB will look like exactly like how can buses are depicted in diagrams and there will be connectors for each of the nodes (ESP32s with a ...
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Sharing CAN bus to two microcontrollers without increasing bus load
I have 2 MCUs in one PCB that I want to communicate via CAN to other devices far away.
Instead of adding two CAN transceivers and becoming two node loads to the network, I thought to combine the two ...
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Changing grounds during start up
We have a system with a CANBUS controlled Battery Management System (BMS) and a PCB with microcontroller. The BMS provides 12V and an isolated CAN ground at all times, but naturally only supplies main ...
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Orange Pi 5 CAN-bus issues
The bus-topology is like this. The CAN-bus has termination resistor at the inverter and in the Waveshare USB/CAN dongle.
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Can Bus issue: 60 ohms without ignition, 165 ohms with ignition on [closed]
I've been having gearbox issues for weeks, seeming to be getting worse. Error was p0753 (gearbox solenoid A electrical) and general can bus timeouts.
Now the car will not crank, because the PATS (...
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Do I need to connect a resistor at the output of an isolated DC-DC converter module?
I am using D050505S-1WR3 in my design for powering an isolated CAN transceiver. The can transceiver is the ISO1042BDWV from TI.
Below is the schematic of the power supply and CAN transceiver.
During ...
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EMC and Control Area Networks [closed]
With radiated EMI tests, do we need to take into account the communication cabling and its influence on EMI?
I can't seem to find one standard that describes how CAN busses should be configured in EMI ...
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How can I use normal CAN with CAN FD?
I'm working with i.MX6ULL not supporting CAN FD but other CAN nodes supports. How can I use normal CAN on this bus without making any hardware changes?
I need to fix CAN to CAN FD communication ...
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Use serial CAN view programs over FT4232H
I have a hardware device that has a FT4232H chip (FTDI chip that makes 4 virtual com ports). Simply put the device is able to speak certain protocols over the generated COM-ports (RS232, TTL, RS485, ...
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How can a CAN transceiver that doesn't support sleep mode emulate a logical sleep state?
Here it is mentioned that the controller will be in a logical sleep state?
If the hardware doesn't support this sleep mode, then how will this logical sleep state be achieved? What is meant by logical ...
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STM32 L4(Nucleo-144) CAN Tx pin stays high and dosen't transmit any data
I'm new to STM32 and a starting knowledge of C. I'm trying to get some level of CAN communication to be working. I've tried looking up the HAL'S required but for some reason no matter what I do, the ...
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Suitable CAN bus connector [closed]
I am searching for suitable CAN bus connector for i.MX nxp ultralite eval board. Is there any suitable connector for it?
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STM32G431CBux and NXP TJA1051T/3/1J
Given is a STM32 G431 CBUx MCU and a TJA1051/3 CAN transciever.
As I also need USB on this MCU, the only way to connect the CAN transceiver are pins PB8 (FDCAN1_Rx) and PB9 (FDCAN1_Tx). The problem ...
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Sending a float type values over CANBUS
I need help in sending float-type values over CANBUS.
I'm working on data acquisition of an fsae car. I'm using Teensy 4.1 and Teensy 3.5 using MCP2562 and MCP2551 CAN transceivers (respectively) to ...
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Understanding ISO-TP, Flow Control and Blocksize
I am currently trying to understand can communication using the ISO 15765-2 (ISO-TP) and Unified Diagnostic Services (UDS) Protocols using can.
At this point I have a question about the Flow Control ...
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Difference between Single-supply and Dual-supply CAN Transceiver
I was about to choose the MCP2558FD CAN Transceiver for a personal project. I found on the datasheet the following diagram:
If my understanding is good, I can use it as a dual-supply Transceiver.
But ...
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CAN Resistor Location Help
Having discussion at work today and wondered if someone could help clear my mind.
We are creating an RS432 network to control 3 aircon units.
The network requires termination using 120 ohm resistors, ...
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CAN Bus sniffing on ECU System
I'm working on designing a communication interface for a poorly documented system that has a proprietary CANbus system.
I want to monitor/listen to the CANbus traffic during system operation to ...
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Is a Deutsch splitter safe to use for CAN bus network?
We want to use Deutsch splitter for a CAN bus network. But I know that CAN bus networks do not like star topology.
My question: Is a Deutsch splitter considered to be a "star"?
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Is it possible to read raw bit of recevied inside MCP2515 RX?
We are using MAX33015E with MCP2515 CAN controller. The MAX33011E has internal fault detection which should be good thing. Our issue that when MAX33011E detects a fault it ...
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dsPIC33CH512MP508 CAN Transmit Error
I am using dspic33ch512mp508. When I call the CAN1_Transmit function, it transmitting continuously with 100us second gaps. Even if I put it in the 1 second timer, it doesn't work.I tested it, the ...
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What component should I use to protect reverse signal for another CAN device?
I am doing some can bus communication using WCMCU-230 and ESP32, I connect two CAN BUS devices with different CAN BUS addresses, so I join the cable directly, and it's working fine with CAN BUS Device-...
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Layout guidelines for TCAN1043DRQ1
I am using TCAN1043DRQ1 in my design.
May I know what are the layout guidelines I need to follow.
I checked the datasheet it. It does not say anything about layout guidelines. It tells more about ...
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How to differentiate slave PCBs that are daisy chained together using one signal from the Master PCB
I need to daisy chain a number of slave pcbs, each with a NXP microcontroller to a master pcb with an esp32. The purpose of each slave is to interface to a motor control chip and handle CAN ...
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CANL and CANH are always active
I have a Linux Ubuntu based Machine and a esp32 which both contain a CAN interface. I am also using two CJMCU-230 transreciver. The Problem is that everytime when I connect the rx and tx of the Linux ...
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What happens if not all nodes ACKnowledged CAN bus frame?
Let's say we have a CAN bus network of 3 nodes: nodeA nodeB nodeC
...
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Why do more transitions imply more bandwidth consumed?
First thing first, I found a question very similar to this one, so if the answer is already in that one please write it down and I will look there.
While studying CAN bus, I read the distinction ...
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Sensitivity and Resolution of Strain Gauges with the ADC
In an assigned exercise I have 6 strain gauges with:
a range of [-5000uε .. 5000uε]
S = 2uε/Volt
They are connected to the CAN bus, and an ADC with 18 bits and Vref = 5V is used.
1) Calculate the ...
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Consumer heartbeat time configuration in CANopen
I have the following situation. I have a master (consumer) and a slave (producer), the slave has to be between nodes 1-127, in this case the slave is in the node 125.
I'm trying to syncronize both of ...
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Why do microcontrollers always need external CAN tranceiver?
For example in STM32 MCUs, the CAN pins are CAN RX and CAN TX. Therefore to transform it to CAN H and CAN L, we need to use external CAN tranceiver. What's the purpose of it? Wouldn't it be easier to ...
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CAN communication in dsPIC33CK64MP508
I tried to transmit data using CAN communication in dsPIC33CK64MP508. I use MCC for configuring CAN in dsPIC33CK64MP508. I set the bit rate to 500 kbps. I just transmit two data bytes (0x41 and 0x42) ...
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CAN-Bus Message confusion
Can anyone tell me what the difference between these two sets of CAN Bus messages? This is from the manual of a Power Drive Unit (PDU) in the Cargo Handling System of a 747F (UPS Freight). This is the ...
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Using Here3+ for GNSS information, missing documentation?
The Here3+ is a GNSS receiver often used by drones, specifically the pixhawk. I wanted to use this receiver in my own project for geopositioning, I am however completely unable to find any ...
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CAN protocol for communication between EV and Charging equipment
I am trying to understand (and hopefully build) DC fast chargers (GB/T) for electric vehicles, specifically the communication between the Electric Vehicle Supply Equipment (EVSE) and the electric ...
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Does a CAN bus DBC file require a 1:1 mapping from CAN ID to message type?
I'm trying to learn more about DBC files and am having trouble a few things that I was hoping people here could help with. My questions are kind of two sides of the same coin:
Can the messages only ...
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CANBUS module connector
I am wondering if someone can suggest a mating connector they used for the MCP2515 CanBus Module (to connect J4). I can not find any datasheet or anything for it but I will be mounting the module to ...
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CAN-Bus: Wire Impedance vs Terminal Resistor
I'm seeing several pre-fabricated "CAN-Bus" cables with (2) DB9, 120 ohm terminal resistor connections, while the cable's impedance is 100 ohms.
A. What is the purpose for this mismatch?
B. ...
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Hardfault STM32 on SystemClock_Config()
I have a custom board with a basic crystal oscillator connected to the High Speed Oscillator pins of my STM32F446RET6.
I assembled 2 boards and found out only 1 board works fine but the other does ...
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Shielded -vs- Non-Shielded, running CAN Data Cable w/ 115/200VAC 3-Phase @ 400Hz
*Edited, AGAIN, in an attempt to remove any confusion
Settle this debate!
I am designing a Harness for testing the functionality of a PDU (Power Drive Unit), operated using CAN (ARINC-825). Prior to ...
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How is a CAN bus like an AND gate?
In this PDF, I read this line:
This
means that the bus can be thought of as acting like an AND gate: If any node writes a dominant (0) bit on
the bus, every node will read a dominant bit regardless ...
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Auto-detecting CAN-Bus bitrate
My team and me are developing our own CAN-Bus adapter. For now, based on the ESP32's integrated CAN-controller, later using an MCP2518fd. I wonder about the best way to auto-detect the configured ...
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CAN Bus Inter Frame Spacing (IFS) -- Three Bits or Seven?
If you google around for the length of the CAN Bus Inter Frame Spacing (IFS), you can find some references that say it's 3 bits and others that say it's 7 bits.
Google Link for 3-bit search
Google ...
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CAN Bus transceiver \$V_{RXD}\$/\$V_{IO}\$ pin confusion
I am looking for a widely available CAN Bus transceiver for a project. I have sorted by availability and found two options that seem to satisfy my criteria. However, they both have an extra pin that I ...
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MCP2515 and Crystal Error
I'm making a board with MCP2515T-I/ML due to space constraints and it won't start up.
(datasheet) https://ww1.microchip.com/downloads/en/DeviceDoc/MCP2515-Stand-Alone-CAN-Controller-with-SPI-20001801J....
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ESP32 TWAI/CANBus bus errors cause bus off state
I have multiple devices using ESP32-WROOM-32E and TWAI (CAN). There was an issue where they would have bus errors and then fail to recover via twai_initiate_recovery(). I solved the recovery issue by ...
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What is the best practice to connect isolated CANBUS transceiver with non-isolated CANBUS transceiver on the same CANBUS network?
CAN Background
According to some places, CAN transceivers do not need GND connections since the line is differential. After long research and understanding how the CAN transceiver works, GND is ...
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CAN FD controller + classic CAN transceiver
I'm currently designing a CAN network that will use a long bus (500 m), so the communication speed won't exceed 50 kbps. Also, I want to use the CAN FD capability to send large 64 byte payload ...
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What would consider a good practice to log CAN physical layer?
We have a CANBUS line and we try to understand different causes for problems. We already logging the CAN from CAN frame perspective. But we would to log electronic events on the CAN line itself.
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