How to enable wifi channels 12 and 13...

Unable to connect to your wifi access point ?

Maybe your WAP use channel 12 or channel 13 and your Raspberry setting is set to a limited radio spectrum, i live in France and here, wifi channels 12 and 13 are legal.

So...

$ sudo apt-get install wireless-regdb iw crda
...
$ sudo iwlist wlan0 channel

wlan0 11 channels in total; available frequencies :
Channel 01 : 2.412 GHz
Channel 02 : 2.417 GHz
Channel 03 : 2.422 GHz
Channel 04 : 2.427 GHz
Channel 05 : 2.432 GHz
Channel 06 : 2.437 GHz
Channel 07 : 2.442 GHz
Channel 08 : 2.447 GHz
Channel 09 : 2.452 GHz
Channel 10 : 2.457 GHz
Channel 11 : 2.462 GHz

As you could see, none of channels 12 or 13 are listed...

Enabling channels for FRANCE:

$ sudo iw reg set FR
...
$ sudo iwlist wlan0 channel

wlan0 11 channels in total; available frequencies :  
          Channel 01 : 2.412 GHz
          Channel 02 : 2.417 GHz
          Channel 03 : 2.422 GHz
          Channel 04 : 2.427 GHz
          Channel 05 : 2.432 GHz
          Channel 06 : 2.437 GHz
          Channel 07 : 2.442 GHz
          Channel 08 : 2.447 GHz
          Channel 09 : 2.452 GHz
          Channel 10 : 2.457 GHz
          Channel 11 : 2.462 GHz
          Channel 12 : 2.467 GHz
          Channel 13 : 2.472 GHz
          Current Frequency:2.472 GHz (Channel 13)

It's better now, but you have to make this setting permanent :

$ sudo nano /etc/default/crda

# Set REGDOMAIN to a ISO/IEC 3166-1 alpha2 country code so that iw(8) may set
# the initial regulatory domain setting for IEEE 802.11 devices which operate
# on this system.
#
# Governments assert the right to regulate usage of radio spectrum +within
# their respective territories so make sure you select a ISO/IEC 3166-1 alpha2
# country code suitable for your location or you may infringe on local
# legislature. See `/usr/share/zoneinfo/zone.tab' for a table of timezone
# descriptions containing ISO/IEC 3166-1 alpha2 country codes.

REGDOMAIN=FR

 Post script : In Japan, channel 14 is available ...