Hardware RTS Enable for Raspberry Pi 3
for The RS485
This code was referenced by below the link.
https://elinux.org/RPi_GPIO_Code_Samples#Direct_register_access

RTS is BCM17 Port
Please See below link
https://pinout.xyz/

$git clone https://github.com/chandong83/raspi3_rts_on

$make -j4

$sudo ./rts_on

$date > /dev/ttyAMA0

if you don't want 'sudo' command

$sudo chown root rts_on
$sudo chmod 4755 rts_on