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5V tolerant pins?

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Post time 2015-10-31 09:09:47 | Show all posts |Read mode
i want to use the uart with an external rs-485 transciever. but my transcievers are 5v supplied, does anyone know if this will damage the orange pi 2?

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Post time 2015-10-31 15:56:47 | Show all posts
UART's on H3 are 16550 compatible and can operates in 16550/16450 mode.
It's like an "old" PC serial port.
If you want to know more look at the H3-datasheet.
Boards:
orangepi plus, olinuxino A20, cubieboard A10, mele A2000 .....

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Post time 2015-10-31 21:41:15 | Show all posts
UART-TX (output from OPI) should have sufficient voltage to drive 5V RS485 transciever
UART-RX (input to OPI) is not 5V tolerant, you can use diode and pullup resistor to 3.3V to drive it
Are you plan to use some "inteligent" RS485 transciever which can be driven only by Tx/Rx ?
If not, you must use UART on expansion connector and enable RTS/CTS lines in fex.

You can also use usb to RS485 converter like this.

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 Author| Post time 2015-10-31 21:59:34 | Show all posts
my transcievers are sp483's (https://www.exar.com/common/content/document.ashx?id=20179). my plan was to use tx/rx for simplicity, i will take special conciderations as to not smoke the opi board then. thanks! you might just have saved me a board
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