Logging into the Raspberry Pi
There are several ways that you can login to the Raspberry Pi in order to get a command prompt.
The default username and password shipped with the image is a username of pi and a password of raspberry
If you plug in an HDMI monitor into the HDMI port on the Raspberry Pi and plug in a USB keybpoard, and reboot the Pi. You should see boot messages and eventually see a login prompt. Enter the username and password as above and you'll be at a bash prompt in the /home/pi directory.
Connect a USB-to-TTL serial cable to the GPIO header pins. Adafruit sells a suitable USB to TTL serial cable and it is connected as pictured:
The black wire is ground and connects to pin 6 (GROUND). The white wire is RX and connects to pin 8 (UART TX). The green wire is TX and connects to pin 10 (UART RX). Leave the red wire (power) unconnected. Refer to the adafruit page for links to drivers for Windows and Mac. Fire up your favorite terminal program at 115200 baud, no flow control and you should see boot messages and a login prompt.
The image that we distribute has the serial console enabled by default.
Firstly, if you have installed the gateway onto the SD card, the rest of this paragraph is unnecessary, since you can just go to the Settings/Developer page and choose the checkbox to "Enable SSH". Otherwise, mount the SD card from the Raspberry Pi in your host computer and create an empty file called ssh (no extension, all lowercase) in the root of the boot partition. There are 2 partitions on the SD card. The first partition is the boot partition and is formatted using FAT, so it should be mountable under Windows, Mac, and Linux. The second partition is EXT4 and is only mountable under Linux.
Properly eject the SD card and then boot up the Raspberry Pi. It will detect the ssh file and enable the SSH server. Login to the Raspberry Pi using:
ssh pi@gateway.local
and provide a password of raspberry. Note that using SSH requires a network connection, either wired or wireless. If you want wireless, then you may need to enable wireless as below.
Note that if you install the gateway, this process is unnecessary, since the gateway will set up its own WiFi link you can connect to, and you tell it your WiFi info, as documented elsewhere. Otherwise, you can create a wpa_supplicant.conf file and put it into the /boot partition (there are 2 partitions on the SD card, the first is a FAT formatted boot partition and the second is an EXT4 formatted partition with the root filesystem). Your wpa_supplicant.conf file should look like this:
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=GB
network={
ssid="WIRLESS_AP_SSID_HERE"
psk="PASSWORD_GOES_HERE"
}
The next time you boot your Raspberry Pi using that SD card it will copy the wpa_supplicant.conf file into the /etc/wpa_supplicant directory (overwriting any previous file).