Linux SoftAP access point mode with wpa_supplicant

To implement an access point with your embedded Linux devices (called soft access point SoftAP mode) or an Ad-Hoc mode network, you need to create a /etc/wpa_supplicant.conf with:

ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=0
fast_reauth=1
update_config=1
 
# -- SoftAP mode
ap_scan=2
network={
                ssid="ath6kl-ap"
                mode=2
                frequency=2412
                key_mgmt=NONE
}

# -- SoftAP mode with encryption/password protected example:
# ap_scan=2
# network={
#       ssid="ath6kl-ap"
#       mode=2
#       frequency=2412
#       key_mgmt=WPA-PSK
#       proto=RSN
#       pairwise=CCMP
#       psk="12345678"
# }

This affords also that the hardware support this mode.