Created
November 17, 2012 20:23
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Macbook ambient light sensor data
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| // Inspired by the code found at | |
| // http://google-mac-qtz-patches.googlecode.com/svn-history/r5/trunk/AmbientLightSensor | |
| // and http://osxbook.com/book/bonus/chapter10/light/ | |
| // http://forums.macrumors.com/showthread.php?t=1133446 | |
| // Compile with $ gcc -o lmutracker lmu.m -framework IOKit -framework CoreFoundation -framework Foundation | |
| #import <Foundation/Foundation.h> | |
| #import <IOKit/IOKitLib.h> | |
| io_connect_t dataPort; | |
| enum { | |
| kGetSensorReadingID = 0, // getSensorReading(int *, int *) | |
| kGetLEDBrightnessID = 1, // getLEDBrightness(int, int *) | |
| kSetLEDBrightnessID = 2, // setLEDBrightness(int, int, int *) | |
| kSetLEDFadeID = 3, // setLEDFade(int, int, int, int *) | |
| }; | |
| int main (int argc, const char * argv[]) { | |
| NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; | |
| kern_return_t kr = KERN_FAILURE; | |
| io_service_t serviceObject; | |
| // Look up a registered IOService object whose class is AppleLMUController | |
| serviceObject = IOServiceGetMatchingService(kIOMasterPortDefault, | |
| IOServiceMatching("AppleLMUController")); | |
| if (serviceObject) { | |
| NSLog(@"Got device AppleLMUController"); | |
| kr = IOServiceOpen(serviceObject, mach_task_self(), 0, &dataPort); | |
| } | |
| IOObjectRelease(serviceObject); | |
| if (kr == KERN_SUCCESS) { | |
| NSLog(@"IOServiceOpen succeeded"); | |
| while (1) { | |
| //Get the ALS reading | |
| uint32_t scalarOutputCount = 2; | |
| uint64_t values[scalarOutputCount]; | |
| kr = IOConnectCallMethod(dataPort, | |
| kGetSensorReadingID, | |
| nil, | |
| 0, | |
| nil, | |
| 0, | |
| values, | |
| &scalarOutputCount, | |
| nil, | |
| 0); | |
| // Get the LED reading | |
| uint32_t scalarInputCountKB = 1; | |
| uint32_t scalarOutputCountKB = 1; | |
| uint64_t in_unknown = 0, out_brightness; | |
| kr = IOConnectCallMethod(dataPort, | |
| kGetLEDBrightnessID, | |
| &in_unknown, | |
| scalarInputCountKB, | |
| nil, | |
| 0, | |
| &out_brightness, | |
| &scalarOutputCountKB, | |
| nil, | |
| 0); | |
| // The code at http://google-mac-qtz-patches.googlecode.com/svn-history/r5/trunk/AmbientLightSensor | |
| // suggests that values be calibrated to 0x00FFFFFF for the MacbookPro5 family and 1600 otherwise | |
| // This seems too low. | |
| // Output as high as 67092480 (0x03ffc000) has been observed on my Macbook 5,2 | |
| // So I'll report the raw value instead and remove the calibration code. | |
| // Also since for the MBP5,2 the two values agree | |
| // (there is only one ALS sensor) I'll report only the maximum value. | |
| // The LED value however does seem to go 0-4091 though the values do not seem fixed. | |
| // They vary with light level and time such that maxing it out results in slightly | |
| // lower values over time. | |
| // Somewhere between 2500000 and 3000000 the KB light turns off. It's hard to capture it since the light ramps off. | |
| NSLog(@"ALS, LED %d,%d",MAX(values[0],values[1]),out_brightness); | |
| sleep(1); //lame way to slow down the output | |
| } | |
| } | |
| [pool drain]; | |
| return 0; | |
| } |
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Thanks to your code, I got the ambient light sensor data in my Macbook. But I have a problem that there are only several numbers, such as 0, 127440, 255240, 382860, ..., 67092480. I tuned the lightness. No matter how dark the light is, the data only changed in the two numbers of 0 and 127440. Could you tell me how to get the data between 0 and 127440?