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--- resources:tools-software:android-drivers:sensor-acceleration:adxl345 [08 Nov 2011 16:42] – [Platform data configuration] fix dead link Lars-Peter Clausen
+++ resources:tools-software:android-drivers:sensor-acceleration:adxl345 [03 Jan 2013 20:42] – external edit
@@ Line 1: / Line 1: @@
+====== ADXL345/6 Android Acceleration Sensor ======
+Using the ADXL345/6 under Android as Acceleration Sensor
+{{:software:driver:android:adxl_sensor_list.png|}}
+The ADXL345/6 can be easily used as Android Acceleration Sensor.
+A few steps are necessary to add appropriate sensor support.
+===== Add Linux Driver Support: =====
+Starting with linux-2.6.36 the ADXL34x driver is mainlined.
+If you are using an pre linux-2.6.36 kernel get the source from our repositories and add them to your kernel tree.
+Example platform data:
+<code c>
+#include <linux/input/adxl34x.h>
+static const struct adxl34x_platform_data adxl34x_info = {
+	.x_axis_offset = 0,
+	.y_axis_offset = 0,
+	.z_axis_offset = 0,
+	.tap_threshold = 0x31,
+	.tap_duration = 0x10,
+	.tap_latency = 0x60,
+	.tap_window = 0xF0,
+	.tap_axis_control = 0,
+	.act_axis_control = 0xFF,
+	.activity_threshold = 5,
+	.inactivity_threshold = 3,
+	.inactivity_time = 4,
+	.free_fall_threshold = 0x7,
+	.free_fall_time = 0x20,
+	.data_rate = 0x8,
+	.data_range = ADXL_FULL_RES,
+	.ev_type = EV_ABS,
+	.ev_code_x = ABS_X,		/* EV_REL */
+	.ev_code_y = ABS_Y,		/* EV_REL */
+	.ev_code_z = ABS_Z,		/* EV_REL */
+	.ev_code_tap = {BTN_0, BTN_1, BTN_2}, /* EV_KEY x,y,z */
+/*	.ev_code_ff = KEY_F,*/		/* EV_KEY */
+/*	.ev_code_act_inactivity = KEY_A,*/	/* EV_KEY */
+	.power_mode = ADXL_AUTO_SLEEP | ADXL_LINK,
+	.fifo_mode = ADXL_FIFO_STREAM,
+	.orientation_enable = 0, /* Disable Orientation Reports */
+	.deadzone_angle = ADXL_DEADZONE_ANGLE_10p8,
+	.divisor_length =  ADXL_LP_FILTER_DIVISOR_16,
+	/* EV_KEY {+Z, +Y, +X, -X, -Y, -Z} */
+	.ev_codes_orient_3d = {BTN_Z, BTN_Y, BTN_X, BTN_A, BTN_B, BTN_C},
+};
+</code>
+===== Create an Android sensor library =====
+The readme file in libhardware states:
+The source code for the "board" variant, usually lives under partners/...
+The source code for "default" and "arch" would usually live under hardware/modules/.
+The sensor file is typically source code for the "board" variant.
+However for simplicity this example puts it into a common folder structure under libhardware/modules/.
+  * Create an sensors folder under libhardware/modules
+  * Copy files sensors_adxl34x.c and Android.mk to libhardware/modules/sensors
+----
+**The files can be downloaded here:**\\
+[[bf>project/android/scmgit/|Android git]]
+  * [[http://blackfin.uclinux.org/git/?p=android;a=blob_plain;f=hardware/sensors/sensors_adxl34x.c;hb=master|sensors_adxl34x.c]]
+  * [[http://blackfin.uclinux.org/git/?p=android;a=blob_plain;f=hardware/sensors/Android.mk;hb=master|Android.mk]]
+----
+  * Make sure the makefile in the higher folder hierarchy picks up the one in libhardware/modules/sensors.
+  * Add following lines to: libhardware/Android.mk
+<code>
+include $(addsuffix /Android.mk, $(addprefix $(LOCAL_PATH)/, \
+			modules/sensors \
+		))
+</code>
+In your platforms init.rc file make sure all ADXL34x drivers sysfs files {disable, rate} are owned by system:system
+  * Add following lines to your init.rc script:
+<code>
+    chown system system /sys/class/input/event0/device/device/disable
+    chown system system /sys/class/input/event0/device/device/rate
+</code>
+<WRAP tip>
+In case the ADXL345/6 is not always event0 you can alternatively approach via /sys/bus/i2c/devices/...
+</WRAP>
+  * Rebuilt your Android tree
+<WRAP tip>
+Upon start the Android log file (use logcat) should include following lines:
+<xterm>
+I/SystemServer( 1862): Sensor Service
+[--snip--]
+D/SensorManager( 2064): found sensor: Analog Devices ADXL345/6 3-axis Accelerometer, handle=0
+</xterm>
+</WRAP>
+===== Hints =====
+==== Sample Rate ====
+The ADXL345/6 sample rate is configurable.
+The maximum sample rate is by default limited to 200Hz, to change this limit modify define ADXL_MAX_SAMPLE_RATE_VAL in the sensor file.
+<WRAP alert>
+Very high sample rates > 400Hz can freeze your system!
+</WRAP>
+<source master/hardware/sensors/sensors_adxl34x.c:control_set_delay{} c android>
+==== Platform data configuration ====
+=== Don't use BTN_TOUCH ===
+In case you experience strange input device gui interaction it might be the case that Android EventHub included the ADXL34x as input device.
+This is typically the case if you put an BTN_TOUCH key into your ADXL34x drivers platform data.
+Upon start EventHub must emit classes=0x0:
+<code>
+I/EventHub( 1862): New device: path=/dev/input/event0 name=ADXL34x accelerometer id=0x10003 (of 0x4) index=4 fd=50 classes=0x0
+</code>
+classes=0x4 means that the ADXL34x driver is considered as Touchscreen.
+=== Auto Sleep ===
+The default platform configuration sets the driver automatically switch to sleep mode during periods of inactivity.
+To disable this feature remove ADXL_AUTO_SLEEP from power_mode.
+Alternatively during runtime:
+<code>
+#echo 0 > /sys/class/input/event0/device/device/autosleep
+</code>
+For more information visit the [[resources/tools-software/linux-drivers/input-misc/adxl345|ADXL34x driver page]]
+==== The Sources ====
+<source master/hardware/sensors/Android.mk c android>
+<source master/hardware/sensors/sensors_adxl34x.c c android>

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