Configuring ext signals - Revision history

HelenF: Moved content to EXT Connector

2014-06-06T20:27:37Z

HelenF: /* UART */ note about PySerial

2014-05-30T14:30:16Z

UART: note about PySerial

← Older revision		Revision as of 14:30, 30 May 2014
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	See the [http://www.cmrr.umn.edu/~strupp/serial.html Serial Programming Guide for POSIX Operating Systems].		See the [http://www.cmrr.umn.edu/~strupp/serial.html Serial Programming Guide for POSIX Operating Systems].

			[http://pyserial.sourceforge.net/shortintro.html PySerial] works for configuring and using the ports.

	==UART3==		==UART3==

HelenF: /* GPIOs */ shell script is slow

2014-05-28T00:20:47Z

GPIOs: shell script is slow

← Older revision		Revision as of 00:20, 28 May 2014
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	echo NNN > /sys/class/gpio/unexport		echo NNN > /sys/class/gpio/unexport
	</source>		</source>

			Controlling the GPIOs with shell script like this is very slow; if speed is required, choose another language to write to the files more efficiently.

	=UART=		=UART=

HelenF: /* Power supply */ expanded voltage warning

2014-05-27T21:18:58Z

Power supply: expanded voltage warning

← Older revision		Revision as of 21:18, 27 May 2014
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	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 unconditionally, 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. The digital I/O pins use 1.8V logic and must not be connected to the 2.8V from the power pin!

	=GPIOs=		=GPIOs=

HelenF: Expanded UART and PWM

2014-05-27T16:35:36Z

Expanded UART and PWM

← Older revision		Revision as of 16:35, 27 May 2014
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	</source>		</source>

	=UART3=		=UART=

			UART2 is mapped to /dev/ttyO1 and UART3 is mapped to /dev/ttyO2.

			The line is high when idle. Each item transmitted has a start bit (low); 5, 6, 7 or 8 data bits; an optional odd or even parity bit; and 1 or 2 stop bits (high).

			These UARTs support a wide range of baud rates. UART2 has the RTS and CTS pins brought out to the EXT connector, while UART3 does not.

			See the [http://www.cmrr.umn.edu/~strupp/serial.html Serial Programming Guide for POSIX Operating Systems].

			==UART3==

	On older firmwares, kernel messages are directed there. SuperZaxxon or later have that disabled.		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.		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:
	<source lang="bash">		<source lang="bash">
Line 219:		Line 232:
	</source>		</source>
	Alternatives are using u-boot environment (configure through USB or UART3 serial before system boots up) or patching and reflashing u-boot itself.		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==
			===Disabling attached terminal===

	For this you need to edit /etc/inittab on pandora rootfs and comment out these lines:		For this you need to edit /etc/inittab on pandora rootfs and comment out these lines:
	<source lang="bash">		<source lang="bash">
	#S0:2345:once:/sbin/getty 115200 ttyS0		#S0:2345:once:/sbin/getty 115200 ttyS0
	#O2:2345:once:/sbin/getty 115200 ttyO2		#O2:2345:once:/sbin/getty 115200 ttyO2
			</source>

			=PWM=

			The UART2 pins on the OMAP could be configured for PWM, but there does not seem to be an interface in the Pandora's OS to do this.

			A wide variety of PWM output can be improvised with a UART. The start bit is always low and the stop bit(s) are always high, but the other bits depend on the character sent and the parity selection. The number of bits per character can be changed between 7 and 12, giving several options for frequency division within each available baud rate.

			<source lang="text">
			_^_^_^_^_^ 8 data bits; frequency=baudrate/2; duty cycle 50%

			_^^^^^^ 5 data bits; frequency=baudrate/7; duty cycle 6/7

			__________^^ 8 data bits, even parity and 2 stop bits; frequency=baudrate/12; duty cycle 1/6
	</source>		</source>

HelenF: /* Pad Configuration Register */ Clarify PULLUDENABLE.

2014-05-25T13:22:12Z

Pad Configuration Register: Clarify PULLUDENABLE.

← Older revision		Revision as of 13:22, 25 May 2014
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	\| 3		\| 3
	\| PULLUDENABLE		\| PULLUDENABLE
	\| 0: pull not active. 1: pull active if pin ~~not~~ configured as ~~output~~.		\| 0: pull not active. 1: pull active when pin direction is configured as input.
	\|-		\|-
	\| 2,1,0		\| 2,1,0

HelenF: /* GPIOs */ Expanded.

2014-05-25T13:18:38Z

GPIOs: Expanded.

@@ Line 170: / Line 170: @@
 =GPIOs=
 Can be controlled using GPIO sysfs class device, as described in beagleboard tutorials [http://bbfordummies.blogspot.com/2009/07/1.html here].
 =UART3=

HelenF: /* Setup */ Removed hashes.

2014-05-25T12:56:15Z

Setup: Removed hashes.

← Older revision		Revision as of 12:56, 25 May 2014
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	<source lang="bash">		<source lang="bash">
	# mkdir /debug		mkdir /debug
	# mount -t debugfs none /debug		mount -t debugfs none /debug
	</source>		</source>

HelenF: Expanded: Pin functions (mux)

2014-05-24T20:35:14Z

Expanded: Pin functions (mux)

Show changes

Notaz: update

2012-11-19T14:28:29Z

update

← Older revision		Revision as of 14:28, 19 November 2012
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	=Pin functions (mux)=		=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.

	~~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=
Line 16:		Line 17:

	=UART3=		=UART3=
	~~By default~~, kernel messages are directed there ~~and a~~ terminal with a shell is attached. The port runs at 115200 8N1 baud rate.		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: