sensors: Return a calculated lux value instead using the current 8 entry table
The light sensor now uses the lux to current formula in the datasheet,
I = 10 * log(Ev) uA, and multiplies the result by 4 as an attempt
to correct for the glass in front of the sensor.
Also update the config_autoBrightnessLevels table so the auto brightness
change occurs at the same adc values as before (or close for 7.26 and
94.5 lux).
Change-Id: I5a54fda8eca26006671064b7db1e39ba0a5d7889
diff --git a/libsensors/LightSensor.cpp b/libsensors/LightSensor.cpp
index c87bacd..a12c218 100644
--- a/libsensors/LightSensor.cpp
+++ b/libsensors/LightSensor.cpp
@@ -80,7 +80,6 @@
{
int flags = en ? 1 : 0;
mEventsSinceEnable = 0;
- mPreviousLight = -1;
if (flags != mEnabled) {
int fd;
strcpy(&input_sysfs_path[input_sysfs_path_len], "enable");
@@ -131,18 +130,21 @@
int type = event->type;
if (type == EV_ABS) {
if (event->code == EVENT_TYPE_LIGHT) {
- mPendingEvent.light = indexToValue(event->value);
+ // Convert adc value to lux assuming:
+ // I = 10 * log(Ev) uA
+ // R = 47kOhm
+ // Max adc value 4095 = 3.3V
+ // 1/4 of light reaches sensor
+ mPendingEvent.light = powf(10, event->value * (330.0f / 4095.0f / 47.0f)) * 4;
if (mEventsSinceEnable < FIRST_GOOD_EVENT)
mEventsSinceEnable++;
}
} else if (type == EV_SYN) {
mPendingEvent.timestamp = timevalToNano(event->time);
- if (mEnabled && (mPendingEvent.light != mPreviousLight) &&
- mEventsSinceEnable >= FIRST_GOOD_EVENT) {
+ if (mEnabled && mEventsSinceEnable >= FIRST_GOOD_EVENT) {
*data++ = mPendingEvent;
count--;
numEventReceived++;
- mPreviousLight = mPendingEvent.light;
}
} else {
LOGE("LightSensor: unknown event (type=%d, code=%d)",
@@ -153,28 +155,3 @@
return numEventReceived;
}
-
-float LightSensor::indexToValue(size_t index) const
-{
- /* Driver gives a rolling average adc value. We convert it lux levels. */
- static const struct adcToLux {
- size_t adc_value;
- float lux_value;
- } adcToLux[] = {
- { 150, 10.0 }, /* from 0 - 150 adc, we map to 10.0 lux */
- { 800, 160.0 }, /* from 151 - 800 adc, we map to 160.0 lux */
- { 900, 225.0 }, /* from 801 - 900 adc, we map to 225.0 lux */
- { 1000, 320.0 }, /* from 901 - 1000 adc, we map to 320.0 lux */
- { 1200, 640.0 }, /* from 1001 - 1200 adc, we map to 640.0 lux */
- { 1400, 1280.0 }, /* from 1201 - 1400 adc, we map to 1280.0 lux */
- { 1600, 2600.0 }, /* from 1401 - 1600 adc, we map to 2600.0 lux */
- { 4095, 10240.0 }, /* from 1601 - 4095 adc, we map to 10240.0 lux */
- };
- size_t i;
- for (i = 0; i < ARRAY_SIZE(adcToLux); i++) {
- if (index < adcToLux[i].adc_value) {
- return adcToLux[i].lux_value;
- }
- }
- return adcToLux[ARRAY_SIZE(adcToLux)-1].lux_value;
-}
diff --git a/libsensors/LightSensor.h b/libsensors/LightSensor.h
index b40283f..2d5ed50 100644
--- a/libsensors/LightSensor.h
+++ b/libsensors/LightSensor.h
@@ -40,8 +40,6 @@
int input_sysfs_path_len;
int setInitialState();
- float mPreviousLight;
- float indexToValue(size_t index) const;
public:
LightSensor();
diff --git a/libsensors/sensors.cpp b/libsensors/sensors.cpp
index ec2d754..1dc128a 100644
--- a/libsensors/sensors.cpp
+++ b/libsensors/sensors.cpp
@@ -82,7 +82,7 @@
{ "GP2A Light sensor",
"Sharp",
1, SENSORS_LIGHT_HANDLE,
- SENSOR_TYPE_LIGHT, 3000.0f, 1.0f, 0.75f, 0, { } },
+ SENSOR_TYPE_LIGHT, powf(10, (280.0f / 47.0f)) * 4, 1.0f, 0.75f, 0, { } },
{ "GP2A Proximity sensor",
"Sharp",
1, SENSORS_PROXIMITY_HANDLE,
diff --git a/overlay/frameworks/base/core/res/res/values/config.xml b/overlay/frameworks/base/core/res/res/values/config.xml
index eb71bf5..0bfc868 100644
--- a/overlay/frameworks/base/core/res/res/values/config.xml
+++ b/overlay/frameworks/base/core/res/res/values/config.xml
@@ -44,11 +44,11 @@
Must be overridden in platform specific overlays -->
<integer-array name="config_autoBrightnessLevels">
- <item>100</item>
- <item>200</item>
- <item>400</item>
- <item>1000</item>
- <item>3000</item>
+ <item>7</item>
+ <item>94</item>
+ <item>208</item>
+ <item>458</item>
+ <item>2223</item>
</integer-array>
<!-- Array of output values for LCD backlight corresponding to the LUX values
