patch-2.4.23 linux-2.4.23/Documentation/wolfson-touchscreen.txt
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- Lines: 179
- Date:
2003-11-28 10:26:19.000000000 -0800
- Orig file:
linux-2.4.22/Documentation/wolfson-touchscreen.txt
- Orig date:
1969-12-31 16:00:00.000000000 -0800
diff -urN linux-2.4.22/Documentation/wolfson-touchscreen.txt linux-2.4.23/Documentation/wolfson-touchscreen.txt
@@ -0,0 +1,178 @@
+
+Wolfson Microelectronics WM9705 and WM9712 Touchscreen Controllers
+===================================================================
+
+The WM9705 and WM9712 are high performance AC97 audio codecs with built
+in touchscreen controllers that are mainly found in portable devices.
+i.e. Dell Axim and Toshiba e740.
+
+This driver uses the AC97 link controller for all communication with the
+codec and can be either built into the kernel or built as a module.
+
+Build Instructions
+==================
+
+The driver will be built into the kernel if "sound card support" = y and
+"wolfson AC97 touchscreen support" = y in the kernel sound configuration.
+
+To build as a module, "wolfson AC97 touchscreen support" = m
+in the kernel sound configuration.
+
+
+Driver Features
+===============
+
+ * supports WM9705, WM9712
+ * polling mode
+ * coordinate polling
+ * adjustable rpu/dpp settings
+ * adjustable pressure current
+ * adjustable sample settle delay
+ * 4 and 5 wire touchscreens (5 wire is WM9712 only)
+ * pen down detection
+ * power management
+ * AUX ADC sampling
+
+
+Driver Usage
+============
+
+In order to use this driver, a char device called wm97xx with a major
+number of 10 and minor number 16 will have to be created under
+/dev/touchscreen.
+
+e.g.
+mknod /dev/touchscreen/wm97xx c 10 16
+
+
+Driver Parameters
+=================
+The driver can accept several parameters for fine tuning the touchscreen.
+However, the syntax is different between module options and passing the
+options in the kernel command line.
+
+e.g.
+
+rpu=1 (module)
+rpu:1 (kernel command line)
+
+
+1. Codec sample mode. (mode)
+
+ The WM9712 can sample touchscreen data in 3 different operating
+ modes. i.e. polling, coordinate and continous.
+
+ Polling:- The driver polls the codec and issues 3 seperate commands
+ over the AC97 link to read X,Y and pressure.
+
+ Coordinate: - The driver polls the codec and only issues 1 command over
+ the AC97 link to read X,Y and pressure. This mode has
+ strict timing requirements and may drop samples if
+ interrupted. However, it is less demanding on the AC97
+ link. Note: this mode requires a larger delay than polling
+ mode.
+
+ Continuous:- The codec automatically samples X,Y and pressure and then
+ sends the data over the AC97 link in slots. This is then
+ same method used by the codec when recording audio.
+
+ Set mode = 0 for polling, 1 for coordinate and 2 for continuous.
+
+ Default mode = 0
+
+
+
+2. WM9712 Internal pull up for pen detect. (rpu)
+
+ Pull up is in the range 1.02k (least sensitive) to 64k (most sensitive)
+ i.e. pull up resistance = 64k Ohms / rpu.
+
+ Adjust this value if you are having problems with pen detect not
+ detecting any down events.
+
+ Set rpu = value
+
+ Default rpu = 1
+
+
+
+3. WM9705 Pen detect comparator threshold. (pdd)
+
+ 0 to Vmid in 15 steps, 0 = use zero power comparator with Vmid threshold
+ i.e. 1 = Vmid/15 threshold
+ 15 = Vmid/1 threshold
+
+ Adjust this value if you are having problems with pen detect not
+ detecting any down events.
+
+ Set pdd = value
+
+ Default pdd = 0
+
+
+
+4. Set current used for pressure measurement. (pil)
+
+ Set pil = 2 to use 400uA
+ pil = 1 to use 200uA and
+ pil = 0 to disable pressure measurement.
+
+ This is used to increase the range of values returned by the adc
+ when measureing touchpanel pressure.
+
+ Default pil = 0
+
+
+
+5. WM9712 Set 5 wire touchscreen mode. (five_wire)
+
+ Set five_wire = 1 to enable 5 wire mode on the WM9712.
+
+ Default five_wire = 0
+
+ NOTE: Five wire mode does not allow for readback of pressure.
+
+
+
+6. ADC sample delay. (delay)
+
+ For accurate touchpanel measurements, some settling time may be
+ required between the switch matrix applying a voltage across the
+ touchpanel plate and the ADC sampling the signal.
+
+ This delay can be set by setting delay = n, where n is the array
+ position of the delay in the array delay_table below.
+ Long delays > 1ms are supported for completeness, but are not
+ recommended.
+
+ Default delay = 4
+
+ wm_delay uS AC97 link frames
+ ====================================
+ 0 21 1
+ 1 42 2
+ 2 84 4
+ 3 167 8
+ 4 333 16
+ 5 667 32
+ 6 1000 48
+ 7 1333 64
+ 8 2000 96
+ 9 2667 128
+ 10 3333 160
+ 11 4000 192
+ 12 4667 224
+ 13 5333 256
+ 14 6000 288
+ 15 0 0 (No delay, switch matrix always on)
+
+
+
+Contact
+=======
+
+Further information about the WM9705 and WM9712 can be found on the
+Wolfson Website. http://www.wolfsonmicro.com
+
+Please report bugs to liam.girdwood@wolfsonmicro.com or
+ linux@wolfsonmicro.com
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