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1

The point of CAN is that you have (usually) a single controller and a single transceiver in a CAN node (some safety critical systems may have more than one bus for redundancy). All CAN nodes talk bidirectionally over the same single wire pair. The number of transmit and recieve buffers (and filters / masks) reduces the load on the firmware. For example if ...


0

No, UART port does not directly correspond to CAN. In the Beaglebone you have physical pins that can be muxed to different peripherals, say pin E16 can be configured as UART0_TXD or as DCAN0_RX, but you can as well have pins that can be configured for CAN but not for UART (say pins D17/D18) and vice versa. If you need a CAN functionality you need to ...


2

The mistake is the way of measuring the impedance. A multimeter will output a precise current to the load and measure the voltage drop, U = R*I gives the Impedance R. If there is already some data traffic on the bus wire this means also additional voltages on the wire. The multimeter can not distinguish between voltage drop due to the injected current and ...


2

On a hardware level: The CAN bus works by a voltage differential between a pair of lines. The Ethernet bus is current-driven and is coupled through transformers at both ends, providing galvanic insulation and avoiding any grounding issue. The electrical operation principle is very different between these buses. Ethernet bus is by default galvanically ...


4

You'll be lucky if the average differential characteristic impedance of your transmission line is within +/- 10% of the nominal 120 ohms; small inaccuracies in the termination network will not have a significant effect. 2x 60.4 ohms will be fine. Even 2x 62 ohms (E24) would be fine. Better to go slightly higher than nominal rather than sightly lower, since ...


0

The specs ought to be clear in the datasheet. Vdd = 4.5V to 5.5V, V IO = 1.8V to 5.5V Use whatever you got in that range, or all 5V


0

No. You will interfere with during switchover, or even short them together temporarily. I've used a relay to extend a CAN bus and this already causes a few lost messages. It's easier to run the 3.3V level signals trough a mux or switch. This way you will not intefere with any of the busses upon switchover or when switched off. Please make sure the ...


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