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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Why does the CAN bus use a 120 ohm resistor as the terminating resistor and not any other value?
I know the reasons for using terminating resistors on a CAN bus and how important it is.
But why 120 ohm? How did this value come up? Is there any specific reason to use 120 ohm?
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Is a CAN enabled microcontroller sufficient to drive a CAN bus?
There are a number of CAN modules built into microcontrollers these days. The PIC18F2480 is an example of that. Is that microcontroller (with built-in CAN) capable of driving a CAN bus on its own or ...
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How to calculate bus load of CAN bus?
I have a few questions regarding CAN bus load
Is there any derived equation/formula to calculate the bus load?
I need transmit below frames(Assume Standard frame format) at baud rate 500 kbps on the ...
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Is a ground/common needed for proper CAN bus communication?
Since CAN Bus is a differential signalling system, what is the significance of GND/COM signal? Can I get by without it?
I've got a very simple 2-node system that has some weird happenings going on. (...
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CAN Transmission and termination resistors
I have been trying to set up a CAN network using PIC18F25K80 microcontrollers and an MCP2551 to communicate between them. Can I use two simple wires as a CAN bus by just connecting the CANL, CANH of ...
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STM32 HAL_CAN_Transmit always returns TIMEOUT (HAL_CAN_STATE_TIMEOUT)
Setup
I am using an STM32F103C8T6 (aka Blue Pill).
With the STM32Cube I set CAN_RX to PB8 and CAN_TX9 to PB9 (these are defaults/nonchangeable).
Circuit
simulate this circuit – Schematic ...
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Implementing a CAN protocol layer in software
Background
I'm developing a project which will require the modest microcontroller specs of:
8 12-bit, 10kHz ADCs
1kB of RAM
48-QFN or smaller footprint
20kbps daisy-chainable noise-resistant and ...
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CAN bus layout design
I am trying to design a CAN bus node. The CAN bus shall be split-terminated with 120Ohm, 60Ohm for each line.
Therefore i tried using this paper to calculate a characteristic impedance of 60Ohm for a ...
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Controller Area Network (CAN), high speed and low speed
Is the difference between high- and low-speed CAN only with respect to baud rate values?
Is the CAN transceiver programmable for a range of speeds or is it fixed for a specific value? For example, can ...
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Difference between buffer and mailbox
Peripherals in Micro-controllers usually provide a way for us to send and receive data from it. Usually this are memory mapped registers.
I have come across few terminologies. The most often used one ...
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CAN bus goes through periods of re-sending messages continually
I'm having an issue where my microprocessor CAN bus module continuously re-sends its last message, even though it seems to be received properly by my USB-CAN monitor on the other end.
I'm attempting ...
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Bus interface for short distances, many device data exchange - CAN, RS485? + characteristic impedance and media capacitance
I ran into some troubles trying to design a wired bus which will connect in about 64 testing devices. My first choice of mind was CAN bus, known of it's reliability and low EMC interference. However, ...
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Can RS485 be considered a multi-master bus?
There are some electrical specifications specifically designed for multi-master protocols such as CAN, I2C, 1-Wire, etc. which are classified under CSMA/CD networks.
However, RS485 has a push pull ...
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Same priority for masters in a CAN network
I'm aware that messages on the CAN network are assigned priorities. I'm working on a 2oo3 voting system, and if each of the messages by the three masters are given three unique id's, I'll be making ...
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What's the maximum CAN bus frame (message) rate at 125 kbit/s?
My CAN bus is running at 125 kbit/s and is using extended frame format exclusively. I would like to know what's the maximum rate of CAN frame I can send out. Suppose the data length is always ...
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Significant differences between CAN and RS485 regarding the physical layer
In comparing the physical layer of CAN and RS485, I am trying to find the advantages of either one over the other. I found out that they are quite similar. Both are good in terms of common mode ...
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What is the color code for CAN Bus?
I would like to know if there is any color code specified for CAN Bus communication wiring, maybe in ISO-11898-1? (I have no free access to the file)
I looked for any official documents without any ...
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What is the limiting factor for a CAN bus to exceed 1Mbps bandwidth?
Why can't CAN baud rate increase beyond 1Mbps
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Why won't my CAN transceiver receive messages unless there is a long startup delay or a bus analyzer connected?
I am using a 16-bit MCU, PIC24HJ64GP504, to write a CAN based application. Basically it is communication between my board and one another node which continuously keeps on sending data to my board ...
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Most efficient way to handle addressing / termination in a daisy-chained CAN bus?
I'm working on some devices that will talk to each other over CAN. The simple idea is to daisy chain essential signals between each device: power (+12V and ground), enable and CAN high / low.
Now, ...
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1-wire verses CAN-bus for home sensing network?
I'm trying to put together a home automation solution for my newly built house. I'm very new to this, specifically for hardware matters and asking this question to verify if my understanding of what I'...
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Effect of splices on 120 Ω twisted pair cable impedance a.k.a correct way to attach stubs to the bus?
I am currently in the process of designing a wiring loom for a race car control system which must also connect a number of devices via a CAN bus.
This is my first encounter with CAN bus (J1939-15) ...
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GND difference between CAN nodes?
I am running a short (2 m) CAN bus with about 20 nodes. 1 Mbit/s speed, PIC 18F2580s and 18F4580s with MCP2551 transceivers, 10 MHz (with PLL to 40 MHz) crystal oscillators. Both ...
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Does it matter which 2 nodes on a CAN bus you terminate?
I know you need to terminate the 'ends' on a high speed CAN bus but what if you know nothing about the topology of the network or where the bus will go. For my application i have designed a data ...
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CAN Bus Physical Layer Twisted pair or not
CAN bus is very common in automotive or vehicular applications. In our case, we are using aerial platforms with have CAN bus links between operator remote and ground control box.
As is very typical ...
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I²C, SPI, CAN protocols and the OSI model
Is there a reference or what is the explanation for I²C and SPI being just physical layer protocols in the OSI model (I know that this model is for communication and maybe not exactly for on-board ...
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How do I program 2 CAN nodes to transmit continuously in succession?
Suppose I have three CAN nodes: A, B and C. We know that when two nodes transmit at the same time, the node that has the least SID will prevail over the bus and the other node will have to give the ...
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Is it possible to have any CAN baudrate?
Is it possible to have any CAN baud values? e.g. 507 baud
If not, on what basis is the standard values are derived?
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CAN bus termination in a fully modular design
I am trying to make a fully modular festo cube design that is controlled with a CAN bus, but I am trying to figure out where to terminate the bus.
I am even not really sure if what I am trying to do ...
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Using an MCU with built-in CAN controller vs. external CAN controller
I'm planning to use the Atmel ATSAMC21J18A microcontroller in an automation project which has a built-in CAN controller. The CAN bus network may contain 32 devices, each generating data packets in 1 ...
