Difference between revisions of "Configuring ext signals"

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=Pin functions (mux)=
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#REDIRECT [[EXT_Connector]]
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 [http://bbfordummies.blogspot.com/2009/07/1.html 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:
 
<source lang="bash">
 
setenv bootargs ubi.mtd=4 ubi.mtd=3 root=ubi0:rootfs rootfstype=ubifs rw rootflags=bulk_read
 
</source>
 
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:
 
<source lang="bash">
 
#S:2345:respawn:/sbin/getty 115200 ttyS0
 
</source>
 

Latest revision as of 20:27, 6 June 2014

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