在 Linux 上使用 I2C 进行读/写

发布于 2024-07-13 00:38:01 字数 1781 浏览 8 评论 0原文

我正在尝试读取/写入通过地址 0b 1010 011 上的 I2C 总线连接的 FM24CL64-GTR FRAM 芯片。

当我尝试写入 3 个字节（数据地址 2 个字节，+ 数据一个字节）时，我收到一条内核消息 ([12406.360000] i2c-adapter i2c-0: sendbytes: NAK bailout。) ，以及写入返回 != 3。请参阅下面的代码：

#include <linux/i2c-dev.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>

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)) < 0)
    exit(1);

if (ioctl(file,I2C_SLAVE,addr) < 0)
    exit(2);

buf[0] = dataAddr >> 8;
buf[1] = dataAddr & 0xff;
buf[2] = val;

if (write(file, buf, 3) != 3)
    exit(3);

...

但是，当我写入 2 个字节，然后写入另一个字节时，我没有收到内核错误，但当尝试从 FRAM 读取时，我总是返回 0。这是从 FRAM 读取的代码：

uint8_t val;

if ((file = open(filename,O_RDWR)) < 0)
    exit(1);

if (ioctl(file,I2C_SLAVE,addr) < 0)
    exit(2);

if (write(file, &dataAddr, 2) != 2) {
    exit(3);

if (read(file, &val, 1) != 1) {
    exit(3);

没有一个函数返回错误值，我也尝试过：

#include <linux/i2c.h>

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) < 0)
    exit(3);

也成功，但始终返回 0。这是否表明硬件问题，或者我做错了什么？

Linux 上是否有通过 I2C 的 FM24CL64-GTR 的 FRAM 驱动程序？API 是什么？任何链接都会有帮助。

原文

I'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 ([12406.360000] i2c-adapter i2c-0: sendbytes: NAK bailout.), as well as the write returns != 3. See code below:

#include <linux/i2c-dev.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>

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)) < 0)
    exit(1);

if (ioctl(file,I2C_SLAVE,addr) < 0)
    exit(2);

buf[0] = dataAddr >> 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)) < 0)
    exit(1);

if (ioctl(file,I2C_SLAVE,addr) < 0)
    exit(2);

if (write(file, &dataAddr, 2) != 2) {
    exit(3);

if (read(file, &val, 1) != 1) {
    exit(3);

None of the functions return an error value, and I have also tried it with:

#include <linux/i2c.h>

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) < 0)
    exit(3);

Which also succeeds, but always returns 0. Does this indicate a hardware issue, or am I doing something wrong?

Are there any FRAM drivers for FM24CL64-GTR over I2C on Linux, and what would the API be? Any link would be helpful.

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