
08-28-2007, 10:23 PM
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Green Apple
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Join Date: Jul 2007
Posts: 75
Thanks: 1
Thanked 5 Times in 5 Posts
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News - iPhone accelerometer source code released
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The iPhone has a built-in LIS302DL, a tiny 3-axis accelerometer and someone has figured out how to take advantage of this natively. For more information and to see a youtube video of some native apps taking advantage of this go here:
http://blog.medallia.com/
For developers interested in the source look below. This is all thanks to Erling Ellingsen from medallia blog. Link posted above.
Code:
#include
#include
typedef struct {} *IOHIDEventSystemRef;
typedef struct {} *IOHIDEventRef;
float IOHIDEventGetFloatValue(IOHIDEventRef ref, int param);
void handleHIDEvent(int a, int b, int c, IOHIDEventRef ptr) {
int type = IOHIDEventGetType(ptr);
if (type == 12) {
float x,y,z;
x = IOHIDEventGetFloatValue(ptr, 0xc0000);
y = IOHIDEventGetFloatValue(ptr, 0xc0001);
z = IOHIDEventGetFloatValue(ptr, 0xc0002);
// do whatever you need to do with the gravity
ballSetAccel(x, y);
}
}
#define expect(x) if(!x) { printf("failed: %s\n", #x); return; }
void initialize(int hz) {
mach_port_t master;
expect(0 == IOMasterPort(MACH_PORT_NULL, &master));
int page = 0xff00, usage = 3;
CFNumberRef nums[2];
CFStringRef keys[2];
keys[0] = CFStringCreateWithCString(0, "PrimaryUsagePage", 0);
keys[1] = CFStringCreateWithCString(0, "PrimaryUsage", 0);
nums[0] = CFNumberCreate(0, kCFNumberSInt32Type, &page);
nums[1] = CFNumberCreate(0, kCFNumberSInt32Type, &usage);
CFDictionaryRef dict = CFDictionaryCreate(0, (const void**)keys, (const void**)nums, 2, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
expect(dict);
IOHIDEventSystemRef sys = (IOHIDEventSystemRef) IOHIDEventSystemCreate(0);
expect(sys);
CFArrayRef srvs = (CFArrayRef)IOHIDEventSystemCopyMatchingServices(s ys, dict, 0, 0, 0);
expect(CFArrayGetCount(srvs)==1);
io_registry_entry_t serv = (io_registry_entry_t)CFArrayGetValueAtIndex(srvs, 0);
expect(serv);
CFStringRef cs = CFStringCreateWithCString(0, "ReportInterval", 0);
int rv = 1000000/hz;
CFNumberRef cn = CFNumberCreate(0, kCFNumberSInt32Type, &rv);
int res = IOHIDServiceSetProperty(serv, cs, cn);
expect(res == 1);
res = IOHIDEventSystemOpen(sys, handleHIDEvent, 0, 0);
expect(res == 0);
}
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