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RS485 and Can Bus Transceiver Connection To Any MCU ?

user4728540
Prodigy 10 points
Other Parts Discussed in Thread: DS89C21, SN65HVD1476

I googled for the question but can't find any answer satisfied. So, how can i make connection between such transceivers and any mcu?

Which pins of MCU should be used?

Can you upload an referance schematic of it?

Thank you in advance...

  • 0
    TI__Mastermind 20820 points

    Hi User4728540,

    RS-485 can be driven from the the GPIO pins on uC or from the UART. The system architect really decides on what the protocol requirements are with 485. For CAN you need to find a uC that has the CAN protocol layer already built in. Here are some uC from TI with this technology:If you opt to not get a uC with the CAN core already in hardware you will have to develop it yourself to implements on a FPGA which is a cumbersome process.

    Please let me know if you have any more questions?

  • 0
    Guru 243870 points
    RS-485 is merely an electrical specification; you have to define your own protocol on top of it. And because RS-485 is half duplex, it does not exactly fit the usual simple protocols such as UART or SPI.

    I'd suggest to use RS-422, which is pretty much the same as RS-485 electrically, but simplex (or full duplex if you use two connections). RS-422 transceiver chips (e.g., DS89C21) can be connected directly to the MCU's UART pins.
  • 0 in reply to Clemens Ladisch
    TI__Mastermind 20820 points

    Hi Clem,

    Just to add a little bit more to your comments here is a link to a full duplex RS-485 part: SN65HVD1476

    RS-422 is limited in its capabilities in that it is multi-drop (1 driver and up to 10 receivers) and not multi-point like RS-485 (up to 256 drivers and receivers on one bus) and it also has a smaller receiver input common mode range. Here is a slide highlighting the differences between RS-485 and RS-422: RS-485 vs RS-422.pdf