11/19/2018 0 Comments I2c Dev.hI'm trying to read/write to a FM24CL64-GTR FRAM chip that is connected over a I2C bus on address 0b 1010 011. When I'm trying to write 3 bytes (data address 2 bytes, + data one byte), I get a kernel message ( [00] i2c-adapter i2c-0: sendbytes: NAK bailout.), as well as the write returns!= 3. See code below: #include #include #include #include int file; char filename[20]; int addr = 0x53; // 0b1010011; /* The I2C address */ uint16_t dataAddr = 0x1234; uint8_t val = 0x5c; uint8_t buf[3]; sprintf(filename,'/dev/i2c-%d',0); if ((file = open(filename,O_RDWR)) > El desarrollo de la personalidad. 8; buf[1] = dataAddr & 0xff; buf[2] = val; if (write(file, buf, 3)!= 3) exit(3). However when I write 2 bytes, then write another byte, I get no kernel error, but when trying to read from the FRAM, I always get back 0. Here is the code to read from the FRAM: uint8_t val; if ((file = open(filename,O_RDWR)) struct i2c_rdwr_ioctl_data work_queue; struct i2c_msg msg[2]; uint8_t ret; work_queue.nmsgs = 2; work_queue.msgs = msg; work_queue.msgs[0].addr = addr; work_queue.msgs[0].len = 2; work_queue.msgs[0].flags = 0; work_queue.msgs[0].buf = &dataAddr; work_queue.msgs[1].addr = addr; work_queue.msgs[1].len = 1; work_queue.msgs[1].flags = I2C_M_RD; work_queue.msgs[1].buf = &ret; if (ioctl(file,I2C_RDWR,&work_queue). I do not have experience with that particular device, but in our experience many I2C devices have 'quirks' that require a work-around, typically above the driver level. We use linux (CELinux) and an I2C device driver with Linux as well. But our application code also has a non-trivial I2C module that contains all the work-around intelligence for dealing with all the various devices we have experience with. Also, when dealing with I2C issues, I often find that I need to re-acquaint myself with the source spec: as well as the usage of a decent oscilloscope. Good luck, Above link is dead, here are some other links: and of course wikipedia. Note that the method using the struct i2c_rdwr_ioctl_data and the struct i2c_msg (that is, the last code part you've given) is more efficient than the other ones, since with that method you execute the repeated start feature of I2c. This means you avoid a STA-WRITE-STO -> STA-READ.-STO transition, because your communication will become STA-WRITE-RS-READ.STO ( RS = repeated start). So, saves you a redundant STO-STA transient. Not that it differs a lot in time, but if it's not needed, why losing on it. If you get a warning about I2C_SLAVE not being defined, you may need to include both i2c.h> and i2c-dev.h> (The location has changed in newer kernels vs. Older kernels and the above example is for newer) Tested Devices. AD7991 Quad Input ADC. Utilized with Sharp GP2D12 IR Range Sensors. (That link is broken. This program is not intended for mobile VR. Blu fresh fish marketplace - catering. Just my 2 ct. ![]() I2cdev.hThere are many references to using i2c_smbus_ functions when developing embedded Linux software to communicate on the I2C bus. When i2c_smbus functions such as i2c_smbus_read_word_data are referenced in software project for ARM8 processor errors such as ‘ i2c_smbus_read_word_data’ was not declared in this scope are generated at compile. Investigation of the following header files indicate the absence of most i2c_smbus function definition. • /usr/arm-linux-gnueabi/include/linux/i2c.h • /usr/arm-linux-gnueabi/include/linux/i2c-dev.h Also in that following reference file has all the i2c_smbus defined. How can this problem be resolved?
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