The following is a source code example of simulating an I2C (IIC) controller using the C language, suitable for general microcontroller platforms (here, it simulates the operation of GPIO pin operations to implement the SCL and SDA lines). The code implements the basic functions of I2C, including initialization, start signal, stop signal, sending acknowledgment bits, receiving acknowledgment bits, sending bytes, and receiving bytes.
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#include <stdint.h> #include <stdbool.h> // Assuming this is the macro definition for GPIO pin operations, it needs to be modified according to the specific hardware platform in actual use #define I2C_SCL_PIN 1 // SCL pin number #define I2C_SDA_PIN 2 // SDA pin number #define SET_SCL() // This should implement the code to set the SCL pin to high, for example, operating on specific GPIO registers #define CLEAR_SCL() // This should implement the code to set the SCL pin to low #define SET_SDA() // This should implement the code to set the SDA pin to high #define CLEAR_SDA() // This should implement the code to set the SDA pin to low #define READ_SDA() // This should implement the code to read the level of the SDA pin, returning a value of 0 or 1 // Simulated I2C delay function, adjust according to actual conditions void i2c_delay(void) { // Simple empty loop delay, adjust the number of loops according to hardware speed for (int i = 0; i < 100; i++); } // I2C initialization function void i2c_init(void) { // Set the SCL and SDA pins to output mode // This should implement the specific GPIO mode setting code SET_SCL(); SET_SDA(); i2c_delay(); } // Generate I2C start signal void i2c_start(void) { SET_SDA(); SET_SCL(); i2c_delay(); CLEAR_SDA(); i2c_delay(); CLEAR_SCL(); i2c_delay(); } // Generate I2C stop signal void i2c_stop(void) { CLEAR_SDA(); SET_SCL(); i2c_delay(); SET_SDA(); i2c_delay(); } // Send acknowledgment bit void i2c_send_ack(void) { CLEAR_SDA(); SET_SCL(); i2c_delay(); CLEAR_SCL(); i2c_delay(); } // Send non-acknowledgment bit void i2c_send_nack(void) { SET_SDA(); SET_SCL(); i2c_delay(); CLEAR_SCL(); i2c_delay(); } // Receive acknowledgment bit, return value:true indicates acknowledgment received, false indicates acknowledgment not received bool i2c_receive_ack(void) { SET_SDA(); // Set SDA to input mode to read acknowledgment signal i2c_delay(); SET_SCL(); i2c_delay(); bool ack = READ_SDA() == 0; CLEAR_SCL(); i2c_delay(); return ack; } // Send a byte of data bool i2c_send_byte(uint8_t byte) { for (int i = 7; i >= 0; i–) { if (byte & (1 << i)) { SET_SDA(); } else { CLEAR_SDA(); } SET_SCL(); i2c_delay(); CLEAR_SCL(); i2c_delay(); } return i2c_receive_ack(); } // Receive a byte of data uint8_t i2c_receive_byte(bool send_ack) { uint8_t byte = 0; SET_SDA(); // Set SDA to input mode for (int i = 7; i >= 0; i–) { SET_SCL(); i2c_delay(); if (READ_SDA()) { byte |= (1 << i); } CLEAR_SCL(); i2c_delay(); } if (send_ack) { i2c_send_ack(); } else { i2c_send_nack(); } return byte; } |
You can call these functions to implement I2C communication as follows:
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int main(void) { i2c_init(); i2c_start(); // Send device address and write flag (assuming device address is 0x50) i2c_send_byte(0x50 << 1 | 0); // Send the data to be written i2c_send_byte(0xAA); i2c_stop(); return 0; } |
The above code is just a basic example of simulating I2C implementation. In actual applications, the code for GPIO operations needs to be modified and improved according to the specific hardware platform (such as different microcontrollers), and further expansion and optimization are required based on specific I2C devices and communication requirements.