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.
889 questions
1 vote
0 answers
66 views
Why might the 3V CAN bus on my car be biased to 1V? [duplicate]
I've been poking around on the CAN bus on my car (2017 Subaru BRZ) and I noticed that even though the CAN bus goes up to 3V, the recessive voltage is only 1V. In other words CANH goes between 1V and ...
0 votes
4 answers
143 views
High speed signals and control impedance traces
What exactly is the definition of a high speed signal? Would you consider a signal of 1 MHz a high frequency signal? Or does it depend on the rise and fall time (the edges are what create harmonics)? ...
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3 votes
1 answer
182 views
Switch for CAN bus
I'm trying to route two CAN bus (CAN-H, CAN-L) lines to a single line. To achieve this goal, I'm designing a switch made up of PhotoMOS (model AQY212S or similar). This is the design: simulate this ...
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0 votes
0 answers
90 views
Bridge between CAN (Control Area Network) and external CAN transreceiver (SpeedGoat I/O Module)
I want to design a bridge for CAN to filter unwanted frequencies and improve EMC.What I mean I expect switching noise from nearby inverters / motor drives / PDUs to couple into the CAN interface (...
0 votes
0 answers
48 views
ESP-32-C3-DEVKIT1 and MCP251863 SPI Error
I am a senior at the University of Kentucky and I am working on my senior design project. I'll skip the fluff, I am working on a PCB to connect an ESP-32-C3-DEVKIT to an MCP251863 to do CAN bus ...
5 votes
2 answers
359 views
High Speed Interfaces - Termination resistors vs Characteristics Impedance
I’m trying to understand the reasoning behind termination requirements in different differential signaling interfaces. For example, USB uses differential signaling (D+ and D–), but the standard does ...
- 1,947
0 votes
1 answer
60 views
CAN Y-Splitter / Non-Twisted Stubs at OBD-II
In an automotive, under dash environment, if I use a Y-adapter at the OBD-II factory port (to share the bus with a CAN controller while keeping the factory port functional), is it acceptable for the ...
- 59
4 votes
1 answer
282 views
Is 20 AWG overkill for CAN_H/CAN_L?
I’m building a CAN bus interface for automotive use, connecting from the OBD-II port (under the dash) to a remote enclosure containing an ESP32 + MCP2515 module, with a total cable length of ~12 feet (...
- 59
0 votes
2 answers
79 views
Optimal MCP2515 Placement for Automotive CAN Bus: At OBD-II Port or Remote MCU?
MCP2515 Placement: Near OBD-II or at MCU? I’m building a CAN bus interface for automotive use, connecting from the OBD-II port (under the dash) to a remote enclosure containing an ESP32 + MCP2515 ...
- 59
0 votes
0 answers
51 views
Am I reading dummy CAN bus data? If so, what did I do wrong?
I am VERY new to electronics, but I love this world. My first project is to read CAN bus data from my 2008 Ford Taurus. I got a MCP2515 CAN Bus Module with a TJA1050 Receiver, and an Arduino. I hooked ...
- 1
3 votes
1 answer
197 views
Different voltage CAN bus transceiver on the same CAN bus
If I have CAN bus transceiver of different voltages on the same CAN bus, will that cause any problem? Scenario If I have 4 nodes on my CAN bus, all of them having isolated ground and an isolated ...
- 579
-1 votes
1 answer
103 views
Unidentified 100x Scaling Factor in Oscilloscope Frequency Reading
The oscilloscope waveform was generated via excel, where the actual oscilloscope readings were captured in a tabular form and then converted into an Excel graph. The readings were taken from an Eaton ...
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3 votes
1 answer
97 views
CANBus fails with custom boards when node added to middle
I’m using the BeagleBone Black Rev C running Debian Linux. We are developing a new agricultural field implement. I have designed a CANBus interface board that uses the MCP2562 transceiver and Molex ...
- 99
0 votes
1 answer
88 views
STM32 FDCAN: Frames visible on CANable (candump) but TX still reports ACK error — scope shows ACK notch
Summary: Two-node bus: STM32 (FDCAN1) ↔ CANable (SocketCAN) at 500 kbit/s candump can0 shows frames from STM32, but STM32 keeps flagging ACK error and increments TxErrorCnt. Scope on CANH/CANL (diff ...
2 votes
0 answers
50 views
CAN bus network compatibility issue with certain diagnostic scanners [closed]
I have a custom CAN bus network consisting of two nodes. The nodes are a MCP2515/TJA1050 boards which are powered by 5 V, and are driven by the SPI protocol at 3V3 from an ESP32. When I connect a PLX ...
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