GPIO - Revision history

Ashcharles at 21:24, 1 April 2016

2016-04-01T21:24:32Z

2013-01-31T17:27:00Z

2013-01-31T17:24:27Z

2012-09-21T09:18:42Z

‎Example: Changing the multiplexing for a pin

2012-09-21T07:28:59Z

‎Example: Changing the multiplexing for a pin

2012-03-15T11:51:38Z

‎40 Pin Expansion Header

2012-03-09T15:07:31Z

‎Overo GPIO

2012-03-09T14:42:02Z

‎Example: Changing the multiplexing for a pin

2011-11-14T04:20:44Z

Fixed links that pointed to gumstix.net

2010-11-23T23:04:51Z

remove spam

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 -----------------------------
 [[Category:Literature]]
 [[Category:GPIO]]

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 See the kernel docs [http://www.kernel.org/doc/Documentation/gpio.txt gpio.txt] for an overview of gpio and the userspace sysfs interface. The "Sysfs Interface for Userspace (OPTIONAL)" section near the end discusses the userspace implementation.
-See the [http://www-s.ti.com/sc/techlit/spruf98 OMAP35X Technical Reference Manual] Section 7.6.3 PADCONFS Register Description and Table 7.5 Core Control Module PadConf Register Field in Section 7.4.4.3 Pad Multiplexing Register Fields for identifying the possible MUX configuration for each GPIO.
+See the [http://www-s.ti.com/sc/techlit/spruf98 OMAP35X Technical Reference Manual] Section 7.6.3 PADCONFS Register Description and Table 7.5 Core Control Module PadConf Register Field in Section 7.4.4.3 Pad Multiplexing Register Fields for identifying the possible MUX configuration for each GPIO. For OVERO DM3730 see the [http://www.ti.com/lit/ug/sprugn4r/sprugn4r.pdf Technical Reference Manual] Section 13.6.3.2 PADCONFS Register Description.
-−
-For OVERO DM3700 see the [http://www.ti.com/lit/ug/sprugn4r/sprugn4r.pdf Technical Reference Manual] Section 13.6.3.2 PADCONFS Register Description.
 Then see the U-Boot source code, board/overo/overo.h for how the pins on the Overo are actually being muxed. See include/asm-arm/arch-omap3/mux.h in the U-Boot tree for the definitions used in overo.h. The pins in mux mode M4 are already configured for GPIO.

← Older revision		Revision as of 17:24, 31 January 2013
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	See the [http://www-s.ti.com/sc/techlit/spruf98 OMAP35X Technical Reference Manual] Section 7.6.3 PADCONFS Register Description and Table 7.5 Core Control Module PadConf Register Field in Section 7.4.4.3 Pad Multiplexing Register Fields for identifying the possible MUX configuration for each GPIO.		See the [http://www-s.ti.com/sc/techlit/spruf98 OMAP35X Technical Reference Manual] Section 7.6.3 PADCONFS Register Description and Table 7.5 Core Control Module PadConf Register Field in Section 7.4.4.3 Pad Multiplexing Register Fields for identifying the possible MUX configuration for each GPIO.
		+
		+	For OVERO DM3700 see the [http://www.ti.com/lit/ug/sprugn4r/sprugn4r.pdf Technical Reference Manual] Section 13.6.3.2 PADCONFS Register Description.

	Then see the U-Boot source code, board/overo/overo.h for how the pins on the Overo are actually being muxed. See include/asm-arm/arch-omap3/mux.h in the U-Boot tree for the definitions used in overo.h. The pins in mux mode M4 are already configured for GPIO.		Then see the U-Boot source code, board/overo/overo.h for how the pins on the Overo are actually being muxed. See include/asm-arm/arch-omap3/mux.h in the U-Boot tree for the definitions used in overo.h. The pins in mux mode M4 are already configured for GPIO.

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   root@overo# devmem2 0x480021c8 h 0x10c
-Now you can export and configure gpio171 from userspace like the example with gpio146 at the beginning.  To make it visible in sysfs.
+Now you can export and configure gpio171 from userspace like the example with gpio146 at the beginning.  To make it visible in sysfs:
   echo 172 > /sys/class/gpio/export

@@ Line 155: / Line 155: @@
   root@overo# devmem2 0x480021c8 h 0x10c
-Now you can export and configure gpio171 from userspace like the example with gpio146 at the beginning.
+Now you can export and configure gpio171 from userspace like the example with gpio146 at the beginning.  To make it visible in sysfs.
 If you want this multiplexing to be permanent, then you would modify the U-Boot file board/overo/overo.h and rebuild U-Boot. If you are using OE, then you'll want to generate a patch file to be used in the u-boot-omap3 recipe.

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 Pin 4 - gpio114<br />
 It's the pendown signal on the touchscreen controller but it's available if you aren't using a expansion board with touchscreen support.<br />
-Configured as input only when exported by the kernel in board-overo.h. Can't change the direction from userspace without modifying kernel.<br />
+This pin can not be configured as output, it is input only (see [http://www-s.ti.com/sc/techlit/spruf98 OMAP35X Technical Reference Manual] p. 3389).
 Pulled-low, reads 0 with no input, reads 1 with an input applied<br />

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 This will make both gpio171 and gpio172 input or output with inputs pulled low.
 === GPIO Software for the Overo ===
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 Here is another article [http://elinux.org/BeagleBoardPinMux BeagleBoardPinMux] talking about OMAP3 pin muxing.
 == Verdex GPIO ==

← Older revision		Revision as of 14:42, 9 March 2012
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	There are additional pins on the header that can be reconfigured this way.		There are additional pins on the header that can be reconfigured this way.
		+
		+	To reconfigure pins from within a kernel module the following code can be used:
		+
		+	void *addr = ioremap(spi1_clk, 4);
		+	if (!addr)
		+	{
		+	printk("Cannot ioremap 0x%lx\n", spi1_clk);
		+	} else {
		+	printk("ioremap OK: 0x%lx\n", spi1_clk);
		+	iowrite32( 0x010C \| (0x010C << 16), addr);
		+	iounmap(addr);
		+	}
		+
		+	This will make both gpio171 and gpio172 input or output with inputs pulled low.

	=== GPIO Software for the Overo ===		=== GPIO Software for the Overo ===

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 Dave Hylands has written several software packages to facilitate GPIO programming on the Overos.
-[http://www.gumstix.net/wiki/index.php?title=GPIO_Event_Driver GPIO Event Driver] allows multiple GPIO lines to be monitored from user-space.
+[[GPIO Event Driver]] allows multiple GPIO lines to be monitored from user-space.
-[http://www.gumstix.net/wiki/index.php?title=User_GPIO_Driver User GPIO Driver] is a reflection of the kernel's gpiolib API into user space.
+[[User GPIO Driver]] is a reflection of the kernel's gpiolib API into user space.
 === More Links ===