Created
July 1, 2021 16:38
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stuff for M1 i2c
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// clang -Wall -fmodules -framework Foundation i2c-rw.m -o ./i2c-rw && sudo ./i2c-rw | |
@import Darwin; | |
@import Foundation; | |
@import IOKit; | |
typedef CFTypeRef IOAVServiceRef; | |
extern IOAVServiceRef IOAVServiceCreate(CFAllocatorRef allocator); | |
extern IOReturn IOAVServiceReadI2C(IOAVServiceRef service, uint32_t chipAddress, | |
uint32_t offset, void *outputBuffer, | |
uint32_t outputBufferSize); | |
extern IOReturn IOAVServiceWriteI2C(IOAVServiceRef service, | |
uint32_t chipAddress, uint32_t dataAddress, | |
void *inputBuffer, | |
uint32_t inputBufferSize); | |
#define BRIGHTNESS 0x10 | |
#define CONTRAST 0x12 | |
#define AUDIO_SPEAKER_VOLUME 0x62 | |
#define AUDIO_MUTE 0x8D | |
#define RW_SIZE 10 | |
int main(int argc, char **argv) { | |
IOAVServiceRef avService = IOAVServiceCreate(kCFAllocatorDefault); | |
if (!avService) { | |
NSLog(@"Can't open IOAVService: do you have an external monitor? Are you " | |
@"root?"); | |
return 1; | |
} | |
UInt8 data[RW_SIZE]; | |
NSData *nsdata; | |
IOReturn err; | |
memset(data, 0, sizeof(data)); | |
err = IOAVServiceReadI2C(avService, 0x37, 0x0, data, sizeof(data)); | |
if (err) { | |
NSLog(@"Nope first i2c: %s", mach_error_string(err)); | |
return 1; | |
} | |
nsdata = [NSData dataWithBytes:(const void *)data | |
length:(NSUInteger)sizeof(data)]; | |
NSLog(@"First read from i2c: %@", nsdata); | |
usleep(30000); | |
data[0] = 0x51; | |
data[1] = 0x82; | |
data[2] = 0x01; | |
data[3] = BRIGHTNESS; | |
data[4] = 0x6e ^ data[0] ^ data[1] ^ data[2] ^ data[3]; | |
uint32_t len = 5; | |
err = IOAVServiceWriteI2C(avService, 0x37, 0x1, data, len); | |
if (err) { | |
NSLog(@"Nope i2c: %s", mach_error_string(err)); | |
return 1; | |
} | |
nsdata = [NSData dataWithBytes:(const void *)data length:(NSUInteger)len]; | |
NSLog(@"Written to i2c: %@", nsdata); | |
usleep(30000); | |
memset(data, 0, sizeof(data)); | |
err = IOAVServiceReadI2C(avService, 0x37, 0x0, data, sizeof(data)); | |
if (err) { | |
NSLog(@"Nope first i2c: %s", mach_error_string(err)); | |
return 1; | |
} | |
nsdata = [NSData dataWithBytes:(const void *)data | |
length:(NSUInteger)sizeof(data)]; | |
NSLog(@"Second read from i2c: %@", nsdata); | |
return 0; | |
} |
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