Configuring ext signals

Pin functions (mux)

Currently this needs recompiling u-boot, but some easier control is planned.

By default UART2 pins are set up as GPIOs, and UART3 as an UART.

Power supply

Currently requires patching bootloaders (xload and u-boot).

This is connected to VAUX3 supply on PMIC, with these programmable voltages (200mA max): 1.5V, 1.8V, 2.5V, 2.8V and 3.0V, with 2.8V as default.

warning: at the time of this writing, both bootloaders (xload and u-boot) set this to 2.8V, so don't rely on this providing other voltages during reboot until you patch both bootloaders.

GPIOs

Can be controlled using GPIO sysfs class device, as described in beagleboard tutorials here.

UART3

By default, kernel messages are directed there and a terminal with a shell is attached. The port runs at 115200 8N1 baud rate.

Disabling kernel messages

To disable kernel mesages, you need to edit kernel boot arguments. Probably easiest way to do it is to create autoboot.txt and place on root directory of a card in slot1 with this content:

setenv bootargs ubi.mtd=4 ubi.mtd=3 root=ubi0:rootfs rootfstype=ubifs rw rootflags=bulk_read

Alternatives are using u-boot environment (configure through USB or UART3 serial before system boots up) or patching and reflashing u-boot itself.

Disabling attached terminal

For this you need to edit /etc/inittab on pandora rootfs and comment out this line:

#S:2345:respawn:/sbin/getty 115200 ttyS0