Difference between revisions of "Configuring ext signals"
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=Pin functions (mux)= | =Pin functions (mux)= | ||
| − | + | By default UART2 pins are set up as GPIOs, and UART3 as an UART. | |
| − | + | ==Changing pin functions under 3.2 kernel== | |
| + | Described in the [http://boards.openpandora.org/index.php?/topic/4497-talking-to-the-gpios-on-the-ext-connector/page__st__40#entry195457 following forum post] | ||
=Power supply= | =Power supply= | ||
| − | Currently requires patching bootloaders (xload and u-boot). | + | Currently always set to supply 2.8V, changing this requires patching bootloaders (xload and u-boot). |
This is connected to VAUX3 supply on PMIC, with these programmable voltages (200mA max): | 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. | 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. | + | '''warning''': at the time of this writing, both bootloaders (xload and u-boot) set this to 2.8V unconditionally, so don't rely on this providing other voltages during reboot until you patch both bootloaders. |
=GPIOs= | =GPIOs= | ||
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=UART3= | =UART3= | ||
| − | + | On older firmwares, kernel messages are directed there. SuperZaxxon or later have that disabled. | |
| + | |||
| + | On all firmwares released so far terminal with a shell is attached to UART3. The port runs at 115200 8N1 baud rate. | ||
==Disabling kernel messages== | ==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: | 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: | ||
Revision as of 14:28, 19 November 2012
Contents
Pin functions (mux)
By default UART2 pins are set up as GPIOs, and UART3 as an UART.
Changing pin functions under 3.2 kernel
Described in the following forum post
Power supply
Currently always set to supply 2.8V, changing this 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 unconditionally, 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
On older firmwares, kernel messages are directed there. SuperZaxxon or later have that disabled.
On all firmwares released so far terminal with a shell is attached to UART3. 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 these lines:
#S0:2345:once:/sbin/getty 115200 ttyS0
#O2:2345:once:/sbin/getty 115200 ttyO2
