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Old 08-31-2018, 08:14 AM   #1
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Unable to use hardware flow control on UART

I am trying to use hardware flow control on serial port ttyS1. The underlying reason I want RTS to be asserted during a write is that the relevant pin is connected to an external RS485 half-duplex transceiver that is set to write mode by a high signal. I tried configuring the port with
struct termios options;
options.c_cflag |= CRTSCTS;
But this has no effect on the relevant pin. I'm on kernel 4.14.0.

I also tried setting the pin to 1 manually from user-space via
to the exported gpio. This does assert the signal, but
returns long before the entire data has actually hit the wire.

Me asking the questions elsewhere for reference:
Old 09-04-2018, 08:00 AM   #2
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You may also want to set CLOCAL when not using a modem.


rts, serial port, tty, uart

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