Adding Hidden wireless (wifi) to Raspberry Pi3

Open the wpa-supplicant configuration file using editor

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

Add the following line to the bottom of the file

 network={ ssid="ssid name"

psk="Password"

}

If you are using a hidden ssid then add one more line

network={
    ssid="yourHiddenSSID"
    scan_ssid=1
    psk="Your_wifi_password" 

}

Using Serial Port - Rx Tx in Raspberry Pi 3

To use Rx Tx pin in Raspberry Pi...

In "/boot/config.txt" edit the last line enable_uart=1

Now use /dev/ttyS0 instead of /dev/ttyAMA0