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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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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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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Correct place to attach shields for twisted pairs
I have two PCBs connected by a cable containing 5 sub-cables:
6v power through a custom made coaxial cable (similar to that found on laptop power supplies).
2x 100mbps LVDS through 100ohm impedance ...
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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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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 Bus Licensing
Looking around for possible solutions for long distance communication between multiple microcontrollers I found the CAN bus. However, it says that there is a licensing fee for any implementation of ...
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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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Transmission of different messages with the SAME ID on a CAN bus
CAN arbitration is done with IDs, and any node on the bus can transmit with any ID (ideally it should not, but a nasty node can).
What if two different nodes connected on the same CAN bus transmit ...
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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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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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Is MCP2551 a UART-to-CAN converter?
I want to make a CAN bus sniffer for 250 kbit/s using my computer. After some research I've found that MCP2551 is some kind of voltage level regulator for CAN's physical layer. Keeping that in ...
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CAN bus signal integrity
The channels are CAN_H (red), CAN_L (blue), and CAN_H-CAN_L (brown).
It can be observed in the diagram below that CAN_H-CAN_L has an acceptable signal shape. However, both CAN_H and CAN_L look poorly ...
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What exactly is "dominant" and "recessive"?
I am reading data sheets on the LIN bus, but apparently the same terminology is used for CAN.
What does "recessive" and "dominant" stand for, e.g http://hw-server.com/products/rs_optika/...
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Enable interrupt but no ISR
I would like to know what happens if an Interrupt is enabled(ex:Arbitration Lost Interrupt in CAN module of NXP's LPC1778),but no ISR has been defined for the interrupt.
When such an interrupt occurs,...
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Selecting a network layer over CAN bus
I am planning on using CAN bus in an industrial automation application, however I'm having a hard time deciding how to implement the network layer. Does anyone here have any recommendations for a ...
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Running CAN bus with RS-485 transceiver
Recently I had a discussion whether one could use RS-485 transceivers for a CAN-bus network in order to gain the flexibility to use the same hardware either in a CAN-environment or in half-duplex RS-...
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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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How to check the CAN bus is free or not
I read a lot of stuff regarding CAN bus arbitration, but it didn't answer my questions.
If one node is already transmitting the data on the bus and in between another node wants to initiate the data ...
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CAN bus test via loopback - possible or not?
I want to test the integrity of the CAN bus (also my CAN transceiver) periodically using the following method (independent of the other nodes).
Assume two nodes always exist (node A and node B). When ...
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Why common-mode choke on differential-signal serial lines?
I have 2 questions:
Why using a common-mode choke on serial communication lines (like CAN, RS485) if the signal is differential? Wouldn't the common-mode noise simply be cancelled in the receiver?
I ...
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Microchip documentation does not label CAN buss pins on micro controller pinout diagram
Link to the data sheet
I want to use Microchips DSPIC33FJ128GP802 in a new project and want to use the ECAN buss.
The problem ...
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For the CAN bus, is it OK to swap CANH and CANL lines?
Similar to question In a USB cable, is it OK to swap the D+ and D- wires?, is it okay if we interconnect CAN-H and CAN-L lines?
CAN is a differential protocol. Is it that dominant and recessive bits ...
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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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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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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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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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How can I determine a maximum run length for CANbus?
I'm using CANbus to communicate between two circuit boards. 120 ohm termination resistors on either end. Transceivers are MCP2561 and ISO1050. Bit rate is in the hundreds of kilobits/second. Medium is ...
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Sync Jump Width (SJW) in Controller Area Network
Is there any drawback to a longer SJW vs a shorter SJW?
The PIC32MZ2048EFH064 has a minimum phase 2 requirement of two time-quanta. This means that the SJW could be one or two time-quanta. Why wouldn'...
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Selecting communication between microcontrollers at high temperature
I have been assigned to a project to find the best possible communication between several PCB boards which have microcontrollers for a specific function. I need to have all microcontrollers ...
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