Advantech EPC-R3710NO-XAA100, User Manual

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17 RSB-3710 User Manual
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Set GPIO value 0/1 if GPIO pin define is output.
Unexport GPIO1.
GPIO 1 and GPIO 2 are taken as an example:
Connect GPIO 1 and GPIO 2
Export GPIO 1 and GPIO 2
Set GPIO 1 to output.
Set GPIO 2 to input.
Change GPIO 1 to 1 and read GPIO 2 value.
Change GPIO 1 to 0 and read GPIO 2 value.
3.4 UART
The Android/Linux UART/serial port access from user is through the tty-devices. The
tty-devices have different names depending on UART driver on different boards.
RS-485 uses half-duplex communication, which means that one medium is shared
for transmitting and receiving data. Therefore the system needs to control the RS-
485 transceiver's transmit mode. Usually the UART RTS signal is used to switch the
transmitter on and off.
$ echo 1 > /sys/class/gpio/gpio504/value
$ echo 504 > /sys/class/gpio/unexport
$ echo 504 > /sys/class/gpio/export
$ echo 505 > /sys/class/gpio/export
$ echo "out" > /sys/class/gpio/gpio504/direction
$ echo "in" > /sys/class/gpio/gpio505/direction
$ echo 1 > /sys/class/gpio/gpio504/value
$ cat /sys/class/gpio/gpio505/value
1
echo 0 > /sys/class/gpio/gpio504/value
$ cat /sys/class/gpio/gpio505/value
0