5V tolerant pins?

matsumo · Published in 2015-10-31 09:09:47

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?

fritz · Published in 2015-10-31 15:56:47

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.

loboris · Published in 2015-10-31 21:41:15

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.

matsumo · Published in 2015-10-31 21:59:34

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

daviddavid · Published in 2023-9-18 17:31:46

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