Changes between Version 10 and Version 11 of gpio

Timestamp:

11/30/2018 12:13:30 AM (5 years ago)

Author:

Cale Collins

Comment:

double edge trigger section added.

gpio

@@ -449 +449 @@
  * The gpio node needs to be at the top level and its placement is arbitrary however its customary to put it in alphabetical order (thus between the '''chosen''' node and the '''leds''' node)
 
-
 BSP Specific notes:
  * OpenWrt replaces the gpio-keys and gpio-keys-polled Linux driver with their out-of-tree driver called gpio-button-hotplug which instead of emiting linux input events emits uevent messages to the button subsystem which tie into the OpenWrt hotplug daemon. See the [wiki:OpenWrt/gpio#button-hotplug-gw OpenWrt/gpio page] for more details.
  * Android can map Linux input events to Android key events via a !KeyLayout file - see [wiki:Android/OSDevelopment#gpio-pushbutton here] for details.
 
-
-References:
+=== Double edge trigger 
+
+OcteonTX GPIO's support double edge trigger, this will create an IRQ for both the leading and falling edge of a signal.  
+
+Here is an example using a GW6304.  
+
+Create an input GPIO and "high" GPIO, these are CPU-DIO's:  
+
+Connect Push button normally open (push-to-make switch) between leads attached to J13 pin 1 and 2.
+
+{{{#!bash
+#Create double edge input GPIO
+echo 488 > /sys/class/gpio/export
+echo in > /sys/class/gpio/gpio488/direction
+echo both > /sys/class/gpio/gpio488/edge 
+#Create "high" GPIO
+echo 489 > /sys/class/gpio/export
+echo out > /sys/class/gpio/gpio489/direction
+echo 1 > /sys/class/gpio/gpio489/value 
+}}}
+Watch IRQ events:
+{{{#!bash
+watch -n 0.5 cat /proc/interrupts 
+}}}
+Look for "GPIO 24 Edge" IRQ count increases on both edges of signal.  
+
+==== References
  * gpio-keys [http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/input/keyboard/gpio_keys.c driver] and [https://lxr.missinglinkelectronics.com/linux/Documentation/devicetree/bindings/input/gpio-keys.txt device-tree bindings]
  * gpio-keys-polled [http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/input/keyboard/gpio_keys_polled.c driver] and  [https://lxr.missinglinkelectronics.com/linux/Documentation/devicetree/bindings/input/gpio-keys-polled.txt device-tree bindings]
@@ -472 +496 @@
  * [wiki:ventana/DigitalIO Ventana product family Digital I/O]
  * [wiki:newport/DigitalIO Newport product family Digital I/O]
+