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dianjixz
79 lines
2.8 KiB
Markdown
79 lines
2.8 KiB
Markdown
## I2C
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I2C (Inter-Integrated Circuit) bus, this is a common serial communication protocol used to connect multiple microcontrollers, sensors, chips, and other external devices.
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Here are important concepts about I2C that beginners need to understand:
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1. **Serial Communication:** I2C is a serial communication protocol that allows multiple devices to communicate on the same line, greatly reducing the number of connecting lines.
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2. **Two-Wire System:** I2C uses two lines for communication: SCL (Serial Clock Line) and SDA (Serial Data Line). SCL is used to transmit clock signals, while SDA is used to transmit data.
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3. **Master-Slave Structure:** I2C communication typically involves two types of devices: master devices and slave devices. The master device generates clock signals and controls communication, while the slave devices respond to instructions from the master device.
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4. **Address Allocation:** Each slave device has a unique 7-bit address on the bus, and the master device uses these addresses to select specific slave devices for communication.
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5. **Frame Format:** I2C communication consists of a series of data frames. Each frame typically includes a start bit, an address byte, data bytes, and a stop bit.
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6. **Clock Synchronization:** The I2C protocol uses clock signals generated by the master device to synchronize communication, ensuring data is transmitted at the correct time.
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7. **Speed:** The I2C communication speed can be set as needed. Standard mode (100 Kbps) and fast mode (400 Kbps) are common speeds.
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8. **Applications:** I2C is widely used in embedded systems, sensors, storage devices, displays, electronic chips, and other fields.
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examples:
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```c
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#include <stdio.h>
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#include <linux_i2c/linuxi2c.h>
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#include <assert.h>
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// Define a bus object
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LINUXI2CDevice i2cdev;
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int main(int argc,char *argv[])
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{
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char i2c_bus[20] = "/dev/i2c-1";
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int ret;
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// init bus object
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linuxi2c_init_device(&i2cdev);
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// open bus
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i2cdev.bus = linuxi2c_open(i2c_bus);
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if(i2cdev.bus <= 0)
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{
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printf("i2c bus: %s open fail!\b", i2c_bus);
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abort();
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}
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char data = 0x01;
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// write data
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ret = linuxi2c_write(&i2cdev, 0x3c, &data, 1);
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if(ret < 0)
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{
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goto end;
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}
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data = 0;
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// read data
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ret = linuxi2c_read(&i2cdev, 0x3c, &data, 1);
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if(ret < 0)
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{
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goto end;
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}
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printf("get i2c bus:%s addr:0x3c val:%x\n", i2c_bus, data);
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end:
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// Release the i2c bus
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linuxi2c_close(i2cdev.bus);
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return 0;
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}
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```
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When compiling the above program, you can compile and run it in the examples/linux_i2c directory of [M5Stack_Linux_Libs]().
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Enter the Linux device:
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``` bash
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# Clone repository
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git clone https://github.com/M5STACK/M5Stack_Linux_Libs.git
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# Enter directory
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cd M5Stack_Linux_Libs/examples/linux_i2c
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# Compile
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scons
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```
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