How to use GPIO for Diagnostic - Revision history

Wei.zeng at 03:17, 20 March 2020

2020-03-20T03:17:04Z

Wei.zeng at 03:16, 20 March 2020

2020-03-20T03:16:24Z

Wei.zeng: Created page with "
2020-03-20T03:14:35Z

Created page with "<span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-size: 14px; font-style: norma..."

New page
<span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; float: none; display: inline !important; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">Please note that Pin configuration/muxing is a non-trivial part of the overall system design. It is easily possible to do illegal configurations when it comes to multiplexed pins (e.g. one pin driving low and the other one driving high). Even more though on SoCs where certain settings in this respect cannot be done per pin but rather only per pin group.

=== Configuration ===

The i.MX bank/bit notation for GPIOs must be formed as "GPIO<GPIO_bank>_IO<gpio_bit>" 

The numeric value of GPIO is calculated as follows:
<pre>32 x (gpio_bank- 1) + gpio_bit
</pre>

E.g. GPIO2_IO04 becomes 36

The Rockchip bank/bit notation for GPIOs must be formed as "GPIO<GPIO_bank>_[A-D]<gpio_bit>" 

The numeric value of GPIO is calculated as follows:
<pre>32 x gpio_bank + gpio_bit
</pre>

E.g. GPIO2_A3 becomes 67，Note：GIPO0 only 24 pins in this group

 

==== [https://developer.toradex.cn/knowledge-base/gpio-(linux)#To_export_a_particular_pin_as_GPIO_for_user_control_proceed_as_follows To export a particular pin as GPIO for user control proceed as follows:] ====
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">$ echo 189 > /sys/class/gpio/export
</pre>

==== [https://developer.toradex.cn/knowledge-base/gpio-(linux)#To_change_that_GPIO_pins_direction_to_inout To change that GPIO pins direction to in/out:] ====
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">$ echo "in" > /sys/class/gpio/gpio189/direction
</pre>

or
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">$ echo "out" > /sys/class/gpio/gpio189/direction
</pre>

==== [https://developer.toradex.cn/knowledge-base/gpio-(linux)#To_check_the_value_in_case_its_direction_is_input To check the value (in case its direction is input):] ====

'''Warning:''' On i.MX based modules one cannot read back the value which has been set to an output unless one did set the SION bit in the pin muxing.
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">$ cat /sys/class/gpio/gpio189/value
</pre>

==== [https://developer.toradex.cn/knowledge-base/gpio-(linux)#To_change_its_value_in_case_its_direction_is_output To change its value (in case its direction is output):] ====
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">$ echo 1 > /sys/class/gpio/gpio189/value
</pre>

or
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">$ echo 0 > /sys/class/gpio/gpio189/value
</pre>

==== [https://developer.toradex.cn/knowledge-base/gpio-(linux)#To_directly_force_a_GPIO_to_output_and_set_its_initial_value_eg_glitch_free_operation To directly force a GPIO to output and set its initial value (e.g. glitch free operation):] ====
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">$ echo high > /sys/class/gpio/gpio189/direction
</pre>

or
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">$ echo low > /sys/class/gpio/gpio189/direction
</pre>

==== [https://developer.toradex.cn/knowledge-base/gpio-(linux)#To_configure_a_GPIO_as_an_interrupt_source To configure a GPIO as an interrupt source:] ====

Note: If a GPIO is configured as an input, one can configure the GPIO as an interrupt source. Configure GPIO if the interrupt occurs when the GPIO signal has a rising edge, a falling edge, or interrupts on both rising and falling edges.
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">$ echo "rising" > /sys/class/gpio/gpio189/edge
</pre>

Possible values
<ul style="list-style: none; padding: 0px 0px 0px 10px; color: rgb(0, 0, 0); text-transform: none; line-height: 26.6px; text-indent: 0px; letter-spacing: normal; font-family: Arial, Helvetica, sans-serif; font-size: 14px; font-style: normal; font-weight: 400; margin-top: 0px; margin-bottom: 0px; word-spacing: 0px; white-space: normal; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">
<li>rising: Trigger on rising edge</li>
<li>falling: Trigger on falling edge</li>
<li>both: Trigger on both edges</li>
<li>none: Disable interrupts on both edges</li>
</ul>

==== [https://developer.toradex.cn/knowledge-base/gpio-(linux)#To_unexport_aka_revert_the_exporting_of_a_GPIO_pin To un-export aka revert the exporting of a GPIO pin:] ====
<pre style="background: rgb(255, 255, 255); margin: 3px 0px; padding: 10px; border-radius: 4px; border: 1px dotted rgb(204, 204, 204); color: rgb(0, 0, 0); text-transform: none; line-height: 1.4285; text-indent: 0px; letter-spacing: normal; overflow: auto; font-family: monospace !important; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; display: block; white-space: pre-wrap; word-break: break-all; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; tab-size: 4; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; hyphens: none;">$ echo 189 > /sys/class/gpio/unexport
</pre>

'''Warning:''' GPIOs which are already used in the drivers can not be controlled from sysfs, unless a driver explicitly exported that particular pins GPIO.

<span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; float: none; display: inline !important; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">More information concerning the Linux' GPIO subsystem can be found in the following kernel documentation file:

[[Gpio.txt|<span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; float: none; display: inline !important; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">GPIO.TXT]]

@@ Line 1: / Line 1: @@
 <span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; float: none; display: inline !important; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">Please note that Pin configuration/muxing is a non-trivial part of the overall system design. It is easily possible to do illegal configurations when it comes to multiplexed pins (e.g. one pin driving low and the other one driving high). Even more though on SoCs where certain settings in this respect cannot be done per pin but rather only per pin group.</span>
 === Configuration ===
@@ Line 79: / Line 79: @@
 <span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; float: none; display: inline !important; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">More information concerning the Linux' GPIO subsystem can be found in the following kernel documentation file:</span>
-[[Media:Gpio.txt|<span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; float: none; display: inline !important; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">GPIO.TXT</span>]]
+<span style="font-size: large;">''<u>'''[[Media:Gpio.txt|<span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-style: normal; font-weight: 400; word-spacing: 0px; float: none; display: inline !important; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">GPIO.TXT</span>]]'''</u>''</span>

← Older revision		Revision as of 03:16, 20 March 2020
Line 79:		Line 79:
	<span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; float: none; display: inline !important; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">More information concerning the Linux' GPIO subsystem can be found in the following kernel documentation file:</span>		<span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; float: none; display: inline !important; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">More information concerning the Linux' GPIO subsystem can be found in the following kernel documentation file:</span>

−	[[Gpio.txt\|<span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; float: none; display: inline !important; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">GPIO.TXT</span>]]	+	[[Media:Gpio.txt\|<span style="color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: arial, helvetica, sans-serif; font-size: 14px; font-style: normal; font-weight: 400; word-spacing: 0px; float: none; display: inline !important; white-space: normal; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">GPIO.TXT</span>]]