Arduino brief notes i2c iic character conversion

About I2C, this is also the previously tangled part. Note.

(For details, refer to: source; Phodal's
Blog)

The I2C (Inter-Integrated Circuit) bus is a two-line serial bus developed by PHILIPS to connect the microcontroller and its peripheral devices. It is a bus standard widely used in the field of microelectronics communication control. > The I2C bus supports any IC production process (nmos cmos, bipolar ). Two-wire-the serial data (SDA) and serial clock (SCL) lines transmit information between devices connected to the bus. Each device has a unique address recognition (whether it is a microcontroller-MCU, LCD driver, memory or keyboard interface ), it can also be used as a transmitter or receiver (determined by the features of the device ). Obviously, the LCD driver is only a receiver, while the memory can receive and send data. Number of devices executed except the transmitter and receiver
Data transmission can also be viewed as a host or slave (see table 1 ). A host is a device that initializes bus data transmission and generates clock signals that can be transmitted. In this case, any addressable device is considered as a slave device.

II2, or I2C, is used in arduino. > Host program example

# Include Wire. h & gt; // declare the I2C library file # define LED 13 byte x = 0; // variable x determines the LED light-off // initialize void setup () {Wire. begin (); // Add the i2c bus as the host pinMode (LED, OUTPUT); // set the number Port 13 to the OUTPUT} // The main program void loop () {Wire. beginTransmission (4); // send data to the slave Wire with device number 4. send ("light is"); // send the string "light is" Wire. send (x); // send a byte Wire in variable x. endTransmission (); // stop sending x ++; // variable x plus 1 if (x = 2) // if the value of variable x is 2, convert x to 0 x = 0; delay (1000); // delay 1 s Wire. requestFr Om (4, 1); // indicates that 1 byte while (Wire. available () & gt; 0) // when the host receives the Slave Data, {byte c = Wire. receive (); // receives a byte value assigned to c // determines that c is 1, then the LED is lit; otherwise, the LED is extinguished. If (c = 1) {digitalWrite (LED, LOW) ;}else {digitalWrite (LED, HIGH) ;}} delay (1000); // latency 1 s}

Brief section of the Arduino slave program

# Include Wire. h & gt; // declare the I2C library file int x; // variable x determines whether the host's LEDs are lit. // initialize void setup () {Wire. begin (4); // Add the i2c bus and set the slave address to #4 Wire. onReceive (receiveEvent); // register the event Wire that receives host characters. onRequest (requestEvent); // register the host to notify the event Serial of data uploaded from the slave. begin (9600); // set the serial port baud rate} // main program void loop () {delay (100); // latency} // when the slave receives host characters, execute this event void receiveEvent (int howevent) {while (Wire. available () & gt; 1) // executes cyclically until the packet contains only the last character {char c = Wire. receive (); // receives the byte Serial as a character. print (c); // print the character to the serial monitor} // receives the last byte x = Wire in the packet sent by the host. receive (); // receives the byte Serial as an integer. println (x); // print the integer to the serial monitor, and press ENTER} // when the host notifies the slave to upload data, execute this event void requestEvent () {// send the last byte of the packet sent by the receiving host to the host Wire. send (x); // sends a byte data to the host in response to the notification from the host}

I2C is mainly dependent on the wire. h library.

Arduino itoa is mainly used for int to char, that is, converting text into characters.

> Itoa is a widely used non-standard C Language extension function. Because it is not a standard C function, it cannot be used in all compilers. However, most compilers (such as those on Windows) usually include this function in header files. The function with the opposite function is atoi. Function: converts an integer to a string.

The usage is as follows:

char *itoa(int value, char *string, int radix);