diff options
Diffstat (limited to 'Documentation/input')
| -rw-r--r-- | Documentation/input/cma3000_d0x.txt | 115 | ||||
| -rw-r--r-- | Documentation/input/multi-touch-protocol.txt | 53 | ||||
| -rw-r--r-- | Documentation/input/ntrig.txt | 126 |
3 files changed, 275 insertions, 19 deletions
diff --git a/Documentation/input/cma3000_d0x.txt b/Documentation/input/cma3000_d0x.txt new file mode 100644 index 0000000..29d088d --- /dev/null +++ b/Documentation/input/cma3000_d0x.txt @@ -0,0 +1,115 @@ +Kernel driver for CMA3000-D0x +============================ + +Supported chips: +* VTI CMA3000-D0x +Datasheet: + CMA3000-D0X Product Family Specification 8281000A.02.pdf + <http://www.vti.fi/en/> + +Author: Hemanth V <hemanthv@ti.com> + + +Description +----------- +CMA3000 Tri-axis accelerometer supports Motion detect, Measurement and +Free fall modes. + +Motion Detect Mode: Its the low power mode where interrupts are generated only +when motion exceeds the defined thresholds. + +Measurement Mode: This mode is used to read the acceleration data on X,Y,Z +axis and supports 400, 100, 40 Hz sample frequency. + +Free fall Mode: This mode is intended to save system resources. + +Threshold values: Chip supports defining threshold values for above modes +which includes time and g value. Refer product specifications for more details. + +CMA3000 chip supports mutually exclusive I2C and SPI interfaces for +communication, currently the driver supports I2C based communication only. +Initial configuration for bus mode is set in non volatile memory and can later +be modified through bus interface command. + +Driver reports acceleration data through input subsystem. It generates ABS_MISC +event with value 1 when free fall is detected. + +Platform data need to be configured for initial default values. + +Platform Data +------------- +fuzz_x: Noise on X Axis + +fuzz_y: Noise on Y Axis + +fuzz_z: Noise on Z Axis + +g_range: G range in milli g i.e 2000 or 8000 + +mode: Default Operating mode + +mdthr: Motion detect g range threshold value + +mdfftmr: Motion detect and free fall time threshold value + +ffthr: Free fall g range threshold value + +Input Interface +-------------- +Input driver version is 1.0.0 +Input device ID: bus 0x18 vendor 0x0 product 0x0 version 0x0 +Input device name: "cma3000-accelerometer" +Supported events: + Event type 0 (Sync) + Event type 3 (Absolute) + Event code 0 (X) + Value 47 + Min -8000 + Max 8000 + Fuzz 200 + Event code 1 (Y) + Value -28 + Min -8000 + Max 8000 + Fuzz 200 + Event code 2 (Z) + Value 905 + Min -8000 + Max 8000 + Fuzz 200 + Event code 40 (Misc) + Value 0 + Min 0 + Max 1 + Event type 4 (Misc) + + +Register/Platform parameters Description +---------------------------------------- + +mode: + 0: power down mode + 1: 100 Hz Measurement mode + 2: 400 Hz Measurement mode + 3: 40 Hz Measurement mode + 4: Motion Detect mode (default) + 5: 100 Hz Free fall mode + 6: 40 Hz Free fall mode + 7: Power off mode + +grange: + 2000: 2000 mg or 2G Range + 8000: 8000 mg or 8G Range + +mdthr: + X: X * 71mg (8G Range) + X: X * 18mg (2G Range) + +mdfftmr: + X: (X & 0x70) * 100 ms (MDTMR) + (X & 0x0F) * 2.5 ms (FFTMR 400 Hz) + (X & 0x0F) * 10 ms (FFTMR 100 Hz) + +ffthr: + X: (X >> 2) * 18mg (2G Range) + X: (X & 0x0F) * 71 mg (8G Range) diff --git a/Documentation/input/multi-touch-protocol.txt b/Documentation/input/multi-touch-protocol.txt index bdcba154..71536e7 100644 --- a/Documentation/input/multi-touch-protocol.txt +++ b/Documentation/input/multi-touch-protocol.txt @@ -1,6 +1,6 @@ Multi-touch (MT) Protocol ------------------------- - Copyright (C) 2009 Henrik Rydberg <rydberg@euromail.se> + Copyright (C) 2009-2010 Henrik Rydberg <rydberg@euromail.se> Introduction @@ -161,19 +161,24 @@ against the glass. The inner region will increase, and in general, the ratio ABS_MT_TOUCH_MAJOR / ABS_MT_WIDTH_MAJOR, which is always smaller than unity, is related to the contact pressure. For pressure-based devices, ABS_MT_PRESSURE may be used to provide the pressure on the contact area -instead. +instead. Devices capable of contact hovering can use ABS_MT_DISTANCE to +indicate the distance between the contact and the surface. In addition to the MAJOR parameters, the oval shape of the contact can be described by adding the MINOR parameters, such that MAJOR and MINOR are the major and minor axis of an ellipse. Finally, the orientation of the oval shape can be describe with the ORIENTATION parameter. +For type A devices, further specification of the touch shape is possible +via ABS_MT_BLOB_ID. + The ABS_MT_TOOL_TYPE may be used to specify whether the touching tool is a -contact or a pen or something else. Devices with more granular information -may specify general shapes as blobs, i.e., as a sequence of rectangular -shapes grouped together by an ABS_MT_BLOB_ID. Finally, for the few devices -that currently support it, the ABS_MT_TRACKING_ID event may be used to -report contact tracking from hardware [5]. +finger or a pen or something else. Finally, the ABS_MT_TRACKING_ID event +may be used to track identified contacts over time [5]. + +In the type B protocol, ABS_MT_TOOL_TYPE and ABS_MT_TRACKING_ID are +implicitly handled by input core; drivers should instead call +input_mt_report_slot_state(). Event Semantics @@ -213,6 +218,12 @@ The pressure, in arbitrary units, on the contact area. May be used instead of TOUCH and WIDTH for pressure-based devices or any device with a spatial signal intensity distribution. +ABS_MT_DISTANCE + +The distance, in surface units, between the contact and the surface. Zero +distance means the contact is touching the surface. A positive number means +the contact is hovering above the surface. + ABS_MT_ORIENTATION The orientation of the ellipse. The value should describe a signed quarter @@ -240,21 +251,24 @@ ABS_MT_TOOL_TYPE The type of approaching tool. A lot of kernel drivers cannot distinguish between different tool types, such as a finger or a pen. In such cases, the event should be omitted. The protocol currently supports MT_TOOL_FINGER and -MT_TOOL_PEN [2]. +MT_TOOL_PEN [2]. For type B devices, this event is handled by input core; +drivers should instead use input_mt_report_slot_state(). ABS_MT_BLOB_ID The BLOB_ID groups several packets together into one arbitrarily shaped -contact. This is a low-level anonymous grouping for type A devices, and +contact. The sequence of points forms a polygon which defines the shape of +the contact. This is a low-level anonymous grouping for type A devices, and should not be confused with the high-level trackingID [5]. Most type A devices do not have blob capability, so drivers can safely omit this event. ABS_MT_TRACKING_ID The TRACKING_ID identifies an initiated contact throughout its life cycle -[5]. This event is mandatory for type B devices. The value range of the -TRACKING_ID should be large enough to ensure unique identification of a -contact maintained over an extended period of time. +[5]. The value range of the TRACKING_ID should be large enough to ensure +unique identification of a contact maintained over an extended period of +time. For type B devices, this event is handled by input core; drivers +should instead use input_mt_report_slot_state(). Event Computation @@ -301,18 +315,19 @@ and with ORIENTATION, one can detect twisting of fingers. Notes ----- -In order to stay compatible with existing applications, the data -reported in a finger packet must not be recognized as single-touch -events. In addition, all finger data must bypass input filtering, -since subsequent events of the same type refer to different fingers. +In order to stay compatible with existing applications, the data reported +in a finger packet must not be recognized as single-touch events. + +For type A devices, all finger data bypasses input filtering, since +subsequent events of the same type refer to different fingers. -The first kernel driver to utilize the MT protocol is the bcm5974 driver, -where examples can be found. +For example usage of the type A protocol, see the bcm5974 driver. For +example usage of the type B protocol, see the hid-egalax driver. [1] With the extension ABS_MT_APPROACH_X and ABS_MT_APPROACH_Y, the difference between the contact position and the approaching tool position could be used to derive tilt. [2] The list can of course be extended. -[3] Multitouch X driver project: http://bitmath.org/code/multitouch/. +[3] The mtdev project: http://bitmath.org/code/mtdev/. [4] See the section on event computation. [5] See the section on finger tracking. diff --git a/Documentation/input/ntrig.txt b/Documentation/input/ntrig.txt new file mode 100644 index 0000000..be1fd98 --- /dev/null +++ b/Documentation/input/ntrig.txt @@ -0,0 +1,126 @@ +N-Trig touchscreen Driver +------------------------- + Copyright (c) 2008-2010 Rafi Rubin <rafi@seas.upenn.edu> + Copyright (c) 2009-2010 Stephane Chatty + +This driver provides support for N-Trig pen and multi-touch sensors. Single +and multi-touch events are translated to the appropriate protocols for +the hid and input systems. Pen events are sufficiently hid compliant and +are left to the hid core. The driver also provides additional filtering +and utility functions accessible with sysfs and module parameters. + +This driver has been reported to work properly with multiple N-Trig devices +attached. + + +Parameters +---------- + +Note: values set at load time are global and will apply to all applicable +devices. Adjusting parameters with sysfs will override the load time values, +but only for that one device. + +The following parameters are used to configure filters to reduce noise: + +activate_slack number of fingers to ignore before processing events + +activation_height size threshold to activate immediately +activation_width + +min_height size threshold bellow which fingers are ignored +min_width both to decide activation and during activity + +deactivate_slack the number of "no contact" frames to ignore before + propagating the end of activity events + +When the last finger is removed from the device, it sends a number of empty +frames. By holding off on deactivation for a few frames we can tolerate false +erroneous disconnects, where the sensor may mistakenly not detect a finger that +is still present. Thus deactivate_slack addresses problems where a users might +see breaks in lines during drawing, or drop an object during a long drag. + + +Additional sysfs items +---------------------- + +These nodes just provide easy access to the ranges reported by the device. +sensor_logical_height the range for positions reported during activity +sensor_logical_width + +sensor_physical_height internal ranges not used for normal events but +sensor_physical_width useful for tuning + +All N-Trig devices with product id of 1 report events in the ranges of +X: 0-9600 +Y: 0-7200 +However not all of these devices have the same physical dimensions. Most +seem to be 12" sensors (Dell Latitude XT and XT2 and the HP TX2), and +at least one model (Dell Studio 17) has a 17" sensor. The ratio of physical +to logical sizes is used to adjust the size based filter parameters. + + +Filtering +--------- + +With the release of the early multi-touch firmwares it became increasingly +obvious that these sensors were prone to erroneous events. Users reported +seeing both inappropriately dropped contact and ghosts, contacts reported +where no finger was actually touching the screen. + +Deactivation slack helps prevent dropped contact for single touch use, but does +not address the problem of dropping one of more contacts while other contacts +are still active. Drops in the multi-touch context require additional +processing and should be handled in tandem with tacking. + +As observed ghost contacts are similar to actual use of the sensor, but they +seem to have different profiles. Ghost activity typically shows up as small +short lived touches. As such, I assume that the longer the continuous stream +of events the more likely those events are from a real contact, and that the +larger the size of each contact the more likely it is real. Balancing the +goals of preventing ghosts and accepting real events quickly (to minimize +user observable latency), the filter accumulates confidence for incoming +events until it hits thresholds and begins propagating. In the interest in +minimizing stored state as well as the cost of operations to make a decision, +I've kept that decision simple. + +Time is measured in terms of the number of fingers reported, not frames since +the probability of multiple simultaneous ghosts is expected to drop off +dramatically with increasing numbers. Rather than accumulate weight as a +function of size, I just use it as a binary threshold. A sufficiently large +contact immediately overrides the waiting period and leads to activation. + +Setting the activation size thresholds to large values will result in deciding +primarily on activation slack. If you see longer lived ghosts, turning up the +activation slack while reducing the size thresholds may suffice to eliminate +the ghosts while keeping the screen quite responsive to firm taps. + +Contacts continue to be filtered with min_height and min_width even after +the initial activation filter is satisfied. The intent is to provide +a mechanism for filtering out ghosts in the form of an extra finger while +you actually are using the screen. In practice this sort of ghost has +been far less problematic or relatively rare and I've left the defaults +set to 0 for both parameters, effectively turning off that filter. + +I don't know what the optimal values are for these filters. If the defaults +don't work for you, please play with the parameters. If you do find other +values more comfortable, I would appreciate feedback. + +The calibration of these devices does drift over time. If ghosts or contact +dropping worsen and interfere with the normal usage of your device, try +recalibrating it. + + +Calibration +----------- + +The N-Trig windows tools provide calibration and testing routines. Also an +unofficial unsupported set of user space tools including a calibrator is +available at: +http://code.launchpad.net/~rafi-seas/+junk/ntrig_calib + + +Tracking +-------- + +As of yet, all tested N-Trig firmwares do not track fingers. When multiple +contacts are active they seem to be sorted primarily by Y position. |