CI20 Headless Setup
This page describes how to set up your CI20 board for headless operation. This is useful if you don't have an HDMI screen available or don't wish to use one.
Getting connected to the serial
The default NAND image uses the UART0 signals which are accessible from the main expansion header near the camera connector. Note that this header is compatible with the Raspberry Pi's expansion header, so much of the RPi Serial Connection article applies to the CI20.
The easiest approach is to purchase a USB to TTL UART adapter. Something like this would probably do (but don't connect the red VCC wire).
Connect the Ground, TXD and RXD wires to pins 6, 8 & 10 of the header. These are the 3rd, 4th and 5th pins on the row nearest the edge of the board:
+------------------------ + | 2 4 [6 8 10] 12 ... | | 1 3 5 7 9 11 ... | | ^ |
See RPi Serial Connection#Connection to a PC for help setting up the serial console.
When you plug in the CI20's power connector you will see text output on the serial console. This comes first from U-Boot, which offers you a chance to interrupt the autoboot in order to get to U-Boot's interactive prompt (from which you can load a different kernel).
If the autoboot is allowed to continue it will load and start the Linux kernel which will output its own boot log on the serial console.
Eventually Debian will present a login prompt:
Debian GNU/Linux 7 ci20 ttyS0 ci20 login:
The default username and password are both "ci20".