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How to connect CAN High speed with CAN Low speed, on the MCU side?

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frdm90

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Hello, I have two TJA1055 (low and high), and I need to connect 4 signals (LS_RX, LS_TX, HS_RX, HS_TX) to MCU, with one pair of RX and TX. Is it possible? Or I misunderstood the exercise.

Thanks in advance.

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Well, It mean, It should be circuit which allows work properlly a CAN with any baud rate.
 

TJA1055 is a low-speed-CAN transceiver 125kbaud.
How do you want to transmit 500kbaud with this transceiver?
Despite of this, the bus levels are completely different, check https://en.wikipedia.org/wiki/CAN_bus
 

Hello, I have two TJA1055 (low and high), and I need to connect 4 signals (LS_RX, LS_TX, HS_RX, HS_TX) to MCU, with one pair of RX and TX. Is it possible? Or I misunderstood the exercise.
Well, It mean, It should be circuit which allows work properlly a CAN with any baud rate.
This again, you didn't like my answers from your other thread so you've started a new thread (against forum rules).

Why don't you use the nomenclature from the TJA1055 datasheet instead of making up your own signal names so nobody can figure out what you are doing?
Here is the block diagram of the TJA1055 use the signal names on the part next time.
Capture.PNG

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Yes I think you misunderstood the exercise just like you've seemed to misunderstand every answer you received on your other thread.

If you want to "share" the connection for RXD and TXD for two of the TJA1055 devices connected to the same microprocessor, I don't really think you can do that (the RXD and TXD lines are not designed for that). Besides that there is no point in doing something like that as having a processor communicate with itself via CAN is just plain silly. I suspect your (school?) assignment doesn't ask you do what you are attempting, it probably asks you to do something entirely different.

Maybe it would be easier if you just posted the assignment question.
 

:shock: Wow, wasn't aware of the older thread.
Maybe only some last words to frdm90, before I step out of this thread:
TJA1055 is a LowSpeedCAN transceiver :!:
The output naming CANH & CANL does NOT indicate Highspeed/Lowspeed.
CAN Bus is differential i/O, so see them as CAN+ & CAN-
TJA1043 is a HighspeedCAN transceiver. Timing & Bus-levels are completely different.

Over and out...
 

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