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maXTouch: Add thresholding so that MOVE reports are not generated unless there is a significant change in the reported position

This commit is contained in:
Gregory Nutt 2014-07-12 14:00:33 -06:00
parent 637e60d95a
commit 44e6516213
3 changed files with 134 additions and 19 deletions
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56
drivers/input/Kconfig
View File

@ -113,8 +113,8 @@ config ADS7843E_THRESHX
default 12
---help---
New touch positions will only be reported when the X or Y data changes by these
thresholds. This trades reduces data rate for some loss in dragging accuracy. For
12-bit values so the raw ranges are 0-4095. So for example, if your display is
thresholds. This trades reduced data rates for some loss in dragging accuracy. For
12-bit values the raw ranges are 0-4095. So for example, if your display is
320x240, then THRESHX=13 and THRESHY=17 would correspond to one pixel. Default: 12
config ADS7843E_THRESHY
@ -122,8 +122,8 @@ config ADS7843E_THRESHY
default 12
---help---
New touch positions will only be reported when the X or Y data changes by these
thresholds. This trades reduces data rate for some loss in dragging accuracy. For
12-bit values so the raw ranges are 0-4095. So for example, if your display is
thresholds. This trades reduced data rates for some loss in dragging accuracy. For
12-bit values the raw ranges are 0-4095. So for example, if your display is
320x240, then THRESHX=13 and THRESHY=17 would correspond to one pixel. Default: 12
endif
@ -136,6 +136,32 @@ config INPUT_MXT
if INPUT_MXT
config MXT_THRESHX
int "X threshold"
default 5
---help---
New touch positions will only be reported when the X or Y data
changes by these thresholds. This trades reduced data rates for some
loss in dragging accuracy. For 12-bit values the raw ranges are
0-4095. So for example, if your display is 800x480, then THRESHX=5
and THRESHY=8 would correspond to a one pixel change. Default: 5
NOTE: This does nothing to reduce the interrupt rate. It only
reduces the rate at which touch events are reports.
config MXT_THRESHY
int "Y threshold"
default 8
---help---
New touch positions will only be reported when the X or Y data
changes by these thresholds. This trades reduced data rates for some
loss in dragging accuracy. For 12-bit values the raw ranges are
0-4095. So for example, if your display is 800x480, then THRESHX=5
and THRESHY=8 would correspond to a one pixel change. Default: 8
NOTE: This does nothing to reduce the interrupt rate. It only
reduces the rate at which touch events are reports.
config MXT_NPOLLWAITERS
int "Number poll waiters"
default 4
@ -143,6 +169,20 @@ config MXT_NPOLLWAITERS
---help---
Maximum number of threads that can be waiting on poll()
config MXT_DISABLE_DEBUG_VERBOSE
bool "Disable verbose debug output"
default y
depends on DEBUG_VERBOSE && DEBUG_INPUT
---help---
The maXTouch tends to generate interrupts at a high rate during the
contact. If verbose debug is enabled in this driver, you may not
be able to get anything done because of the high debug output rate.
This setting will allow you to keep verbose touchscreen debug output
in other modules, but to specifically suppress the debug out from
the MXT driver. Debug (non-verbose) errors will still be generated,
but the chit-chat level will be eliminated.
endif # INPUT_MXT
config INPUT_STMPE811
@ -223,8 +263,8 @@ config STMPE811_THRESHX
---help---
STMPE811 touchscreen data comes in a a very high rate. New touch positions
will only be reported when the X or Y data changes by these thresholds.
This trades reduces data rate for some loss in dragging accuracy. The
STMPE811 is configure for 12-bit values so the raw ranges are 0-4095. So
This trades reduced data rates for some loss in dragging accuracy. The
STMPE811 is configure for 12-bit values the raw ranges are 0-4095. So
for example, if your display is 320x240, then THRESHX=13 and THRESHY=17
would correspond to one pixel. Default: 12
@ -235,8 +275,8 @@ config STMPE811_THRESHY
---help---
STMPE811 touchscreen data comes in a a very high rate. New touch positions
will only be reported when the X or Y data changes by these thresholds.
This trades reduces data rate for some loss in dragging accuracy. The
STMPE811 is configure for 12-bit values so the raw ranges are 0-4095. So
This trades reduced data rates for some loss in dragging accuracy. The
STMPE811 is configure for 12-bit values the raw ranges are 0-4095. So
for example, if your display is 320x240, then THRESHX=13 and THRESHY=17
would correspond to one pixel. Default: 12

77
drivers/input/mxt.c
View File

@ -39,6 +39,12 @@
#include <nuttx/config.h>
/* Suppress verbose debug output so that we don't swamp the system */
#ifdef CONFIG_MXT_DISABLE_DEBUG_VERBOSE
# undef CONFIG_DEBUG_VERBOSE
#endif
#include <sys/types.h>
#include <stdbool.h>
@ -74,6 +80,12 @@
#define DEV_FORMAT "/dev/input%d"
#define DEV_NAMELEN 16
/* This is a value for the threshold that guarantees a big difference on the
* first pendown (but can't overflow).
*/
#define INVALID_POSITION 0x1000
/* Get a 16-bit value in little endian order (not necessarily aligned). The
* source data is in little endian order. The host byte order does not
* matter in this case.
@ -123,6 +135,8 @@ struct mxt_sample_s
bool valid; /* True: x,y,pressure contain valid, sampled data */
uint16_t x; /* Measured X position */
uint16_t y; /* Measured Y position */
uint16_t lastx; /* Last reported X position */
uint16_t lasty; /* Last reported Y position */
uint8_t area; /* Contact area */
uint8_t pressure; /* Contact pressure */
};
@ -824,6 +838,13 @@ static void mxt_touch_event(FAR struct mxt_dev_s *priv,
*/
sample->contact = CONTACT_LOST;
/* Reset the last position so that we guarantee that the next position
* will pass the thresholding test.
*/
sample->lastx = INVALID_POSITION;
sample->lasty = INVALID_POSITION;
}
else
{
@ -847,21 +868,49 @@ static void mxt_touch_event(FAR struct mxt_dev_s *priv,
sample->valid = true;
/* If this is not the first touch report, then report it as a move:
* Same contact, same ID, but a potentially new position. If
* The move event has not been reported, then just overwrite the
* move. That is harmless.
* Same contact, same ID, but with a new, updated position.
* The CONTACT_REPORT state means that a contacted has been detected,
* but all contact events have been successfully reported.
*/
if (sample->contact == CONTACT_REPORT ||
sample->contact == CONTACT_MOVE)
if (sample->contact == CONTACT_REPORT)
{
/* Not a new contact. Indicate a contact move event */
uint16_t xdiff;
uint16_t ydiff;
sample->contact = CONTACT_MOVE;
/* This state will be set to CONTACT_REPORT after it
* been reported.
/* Not a new contact. Check if the new measurements represent a
* non-trivial change in position. A trivial change is detected
* by comparing the change in position since the last report
* against configurable threshold values.
*
* REVISIT: Should a large change in pressure also generate a
* event?
*/
xdiff = x > sample->lastx ? (x - sample->lastx) : (sample->lastx - x);
ydiff = y > sample->lasty ? (y - sample->lasty) : (sample->lasty - y);
/* Check the thresholds */
if (xdiff < CONFIG_MXT_THRESHX && ydiff < CONFIG_MXT_THRESHY)
{
/* Report a contact move event. This state will be set back
* to CONTACT_REPORT after it been reported.
*/
sample->contact = CONTACT_MOVE;
/* Update the last position for next threshold calculations */
sample->lastx = x;
sample->lasty = y;
}
else
{
/* Bail without reporting anything for this event */
return;
}
}
/* If we have seen this contact before but it has not yet been
@ -872,7 +921,8 @@ static void mxt_touch_event(FAR struct mxt_dev_s *priv,
* above) and we have a new contact with a new ID.
*/
else if (sample->contact != CONTACT_NEW)
else if (sample->contact != CONTACT_NEW &&
sample->contact != CONTACT_MOVE)
{
/* First contact. Save the contact event and assign a new
* ID to the contact.
@ -881,6 +931,11 @@ static void mxt_touch_event(FAR struct mxt_dev_s *priv,
sample->contact = CONTACT_NEW;
sample->id = priv->id++;
/* Update the last position for next threshold calculations */
sample->lastx = x;
sample->lasty = y;
/* This state will be set to CONTACT_REPORT after it
* been reported.
*/

20
include/nuttx/input/mxt.h
View File

@ -59,6 +59,26 @@
# define CONFIG_MXT_NPOLLWAITERS 2
#endif
/* Thresholding
*
* New touch positions will only be reported when the X or Y data
* changes by these thresholds. This trades reduced data rates for some
* loss in dragging accuracy. For 12-bit values the raw ranges are
* 0-4095. So for example, if your display is 800x480, then THRESHX=5
* and THRESHY=8 would correspond to a one pixel change.
*
* NOTE: This does nothing to reduce the interrupt rate. It only
* reduces the rate at which touch events are reports.
*/
#ifndef CONFIG_MXT_MXT_THRESHX
# define CONFIG_MXT_MXT_THRESHX 5
#endif
#ifndef CONFIG_MXT_MXT_THRESHY
# define CONFIG_MXT_MXT_THRESHY 8
#endif
/* Buttons are not supported */
#undef CONFIG_MXT_BUTTONS