mirror of
https://github.com/clockworkpi/WiringPi.git
synced 2025-12-12 16:08:49 +01:00
b1dfc186ef
for kernels 4.8 onwards. Some very old stuff might break. Additional fixes for the ISR code and some tweaks here and there. I've removed the checks for some operations that might fail when using the gpiomem interface - which is now the default way of doing things - if your program segfaults, then you may need to use sudo on it.
234 lines
6.3 KiB
C
234 lines
6.3 KiB
C
/*
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* wiringPiI2C.c:
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* Simplified I2C access routines
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* Copyright (c) 2013 Gordon Henderson
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***********************************************************************
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* This file is part of wiringPi:
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* https://projects.drogon.net/raspberry-pi/wiringpi/
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*
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* wiringPi is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* wiringPi is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with wiringPi.
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* If not, see <http://www.gnu.org/licenses/>.
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***********************************************************************
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*/
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/*
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* Notes:
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* The Linux I2C code is actually the same (almost) as the SMBus code.
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* SMBus is System Management Bus - and in essentially I2C with some
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* additional functionality added, and stricter controls on the electrical
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* specifications, etc. however I2C does work well with it and the
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* protocols work over both.
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*
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* I'm directly including the SMBus functions here as some Linux distros
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* lack the correct header files, and also some header files are GPLv2
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* rather than the LGPL that wiringPi is released under - presumably because
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* originally no-one expected I2C/SMBus to be used outside the kernel -
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* however enter the Raspberry Pi with people now taking directly to I2C
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* devices without going via the kernel...
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*
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* This may ultimately reduce the flexibility of this code, but it won't be
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* hard to maintain it and keep it current, should things change.
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*
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* Information here gained from: kernel/Documentation/i2c/dev-interface
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* as well as other online resources.
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*********************************************************************************
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <errno.h>
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#include <string.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <asm/ioctl.h>
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#include "wiringPi.h"
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#include "wiringPiI2C.h"
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// I2C definitions
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#define I2C_SLAVE 0x0703
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#define I2C_SMBUS 0x0720 /* SMBus-level access */
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#define I2C_SMBUS_READ 1
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#define I2C_SMBUS_WRITE 0
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// SMBus transaction types
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#define I2C_SMBUS_QUICK 0
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#define I2C_SMBUS_BYTE 1
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#define I2C_SMBUS_BYTE_DATA 2
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#define I2C_SMBUS_WORD_DATA 3
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#define I2C_SMBUS_PROC_CALL 4
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#define I2C_SMBUS_BLOCK_DATA 5
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#define I2C_SMBUS_I2C_BLOCK_BROKEN 6
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#define I2C_SMBUS_BLOCK_PROC_CALL 7 /* SMBus 2.0 */
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#define I2C_SMBUS_I2C_BLOCK_DATA 8
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// SMBus messages
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#define I2C_SMBUS_BLOCK_MAX 32 /* As specified in SMBus standard */
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#define I2C_SMBUS_I2C_BLOCK_MAX 32 /* Not specified but we use same structure */
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// Structures used in the ioctl() calls
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union i2c_smbus_data
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{
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uint8_t byte ;
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uint16_t word ;
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uint8_t block [I2C_SMBUS_BLOCK_MAX + 2] ; // block [0] is used for length + one more for PEC
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} ;
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struct i2c_smbus_ioctl_data
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{
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char read_write ;
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uint8_t command ;
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int size ;
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union i2c_smbus_data *data ;
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} ;
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static inline int i2c_smbus_access (int fd, char rw, uint8_t command, int size, union i2c_smbus_data *data)
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{
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struct i2c_smbus_ioctl_data args ;
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args.read_write = rw ;
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args.command = command ;
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args.size = size ;
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args.data = data ;
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return ioctl (fd, I2C_SMBUS, &args) ;
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}
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/*
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* wiringPiI2CRead:
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* Simple device read
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*********************************************************************************
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*/
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int wiringPiI2CRead (int fd)
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{
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union i2c_smbus_data data ;
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if (i2c_smbus_access (fd, I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &data))
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return -1 ;
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else
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return data.byte & 0xFF ;
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}
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/*
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* wiringPiI2CReadReg8: wiringPiI2CReadReg16:
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* Read an 8 or 16-bit value from a regsiter on the device
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*********************************************************************************
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*/
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int wiringPiI2CReadReg8 (int fd, int reg)
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{
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union i2c_smbus_data data;
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if (i2c_smbus_access (fd, I2C_SMBUS_READ, reg, I2C_SMBUS_BYTE_DATA, &data))
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return -1 ;
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else
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return data.byte & 0xFF ;
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}
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int wiringPiI2CReadReg16 (int fd, int reg)
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{
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union i2c_smbus_data data;
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if (i2c_smbus_access (fd, I2C_SMBUS_READ, reg, I2C_SMBUS_WORD_DATA, &data))
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return -1 ;
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else
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return data.word & 0xFFFF ;
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}
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/*
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* wiringPiI2CWrite:
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* Simple device write
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*********************************************************************************
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*/
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int wiringPiI2CWrite (int fd, int data)
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{
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return i2c_smbus_access (fd, I2C_SMBUS_WRITE, data, I2C_SMBUS_BYTE, NULL) ;
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}
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/*
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* wiringPiI2CWriteReg8: wiringPiI2CWriteReg16:
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* Write an 8 or 16-bit value to the given register
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*********************************************************************************
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*/
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int wiringPiI2CWriteReg8 (int fd, int reg, int value)
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{
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union i2c_smbus_data data ;
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data.byte = value ;
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return i2c_smbus_access (fd, I2C_SMBUS_WRITE, reg, I2C_SMBUS_BYTE_DATA, &data) ;
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}
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int wiringPiI2CWriteReg16 (int fd, int reg, int value)
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{
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union i2c_smbus_data data ;
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data.word = value ;
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return i2c_smbus_access (fd, I2C_SMBUS_WRITE, reg, I2C_SMBUS_WORD_DATA, &data) ;
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}
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/*
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* wiringPiI2CSetupInterface:
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* Undocumented access to set the interface explicitly - might be used
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* for the Pi's 2nd I2C interface...
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*********************************************************************************
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*/
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int wiringPiI2CSetupInterface (const char *device, int devId)
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{
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int fd ;
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if ((fd = open (device, O_RDWR)) < 0)
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return wiringPiFailure (WPI_ALMOST, "Unable to open I2C device: %s\n", strerror (errno)) ;
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if (ioctl (fd, I2C_SLAVE, devId) < 0)
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return wiringPiFailure (WPI_ALMOST, "Unable to select I2C device: %s\n", strerror (errno)) ;
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return fd ;
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}
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/*
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* wiringPiI2CSetup:
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* Open the I2C device, and regsiter the target device
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*********************************************************************************
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*/
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int wiringPiI2CSetup (const int devId)
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{
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int rev ;
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const char *device ;
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rev = piGpioLayout () ;
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if (rev == 1)
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device = "/dev/i2c-0" ;
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else
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device = "/dev/i2c-1" ;
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return wiringPiI2CSetupInterface (device, devId) ;
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}
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