As the clock pulse changes from low to high (known as the rising edge of the clock), a bit of information containing the address of a specific device and a request for data, is transferred from the Arduino to the I2C devices over the SDA line.
#ARDUING WIRE LIBRARY SERIAL#
The I2C protocol involves using two wires to send and receive data: a serial clock pin (SCL) that the Arduino pulses at a regular interval, and a serial data pin (SDA) over which data is sent between the two devices. Once that message is received, it can then be viewed in the Arduino serial window. Arduino 1, the Master, is programmed to request, and then read, 6 bytes of data sent from the uniquely addressed Slave Arduino. Several functions of Arduino's Wire Library are used to accomplish this. In this example, two Arduinos are programmed to communicate with one another in a Master Reader/Slave Sender configuration via the I2C synchronous serial protocol. In some situations, it can be helpful to set up two (or more!) Arduino boards to share information with each other. If(Wire.Learning Examples | Foundations | Hacking | Links Wire.requestFrom(0x08, 1) // request potentiometer position from slave 0x08 Wire.endTransmission() // informs the bus and the slave device that we have finished sending data Wire.beginTransmission(0x08) // informs the bus that we will be sending data to slave device 8 (0x08) send potentiometer position to Slave device 0x08 Value_pot = analogRead(A0) // read the voltage at pin A0 (potentiometer voltage) PinMode(13, OUTPUT) // set pin 13 as an output Wire.begin() // join I2C bus as the master Int stat_LED // status of LED: 1 = ON, 0 = OFFīyte value_pot // potentiometer position Unsigned long time_start // start time in milliseconds
#ARDUING WIRE LIBRARY CODE#
Open the Arduino IDE and upload the code below to the master Arduino: // Arduino master sketchīyte i2c_rcv // data received from I2C bus One is for the master Arduino, and the other is for the slave Arduino. We have two Arduinos in our I2C network, so we have two sets of sketches. We don’t need pull-up resistors on the SDA and SCL lines, because they’re built into the Arduino’s I2C pins already. The device’s datasheet should tell you it’s logic level voltage. An I2C device that operates at 3.3V could be damaged if connected to the Arduino. But I2C devices can operate at a range of different logic level voltages. The Arduino outputs I2C signals at a 5V logic level. Pull-up resistors are used to keep both wires in a HIGH state by default. The SCL line carries the clock signal used for communication timing. The SDA wire is used for sending the actual data back and forth between the master and slave devices. The BusĪn I2C bus is simply two wires that connect all of the I2C devices in the network. When sending data on the bus, only one device can send data at a time. Slave devices respond to whatever a master device sends. Master devices can send and receive data. The I2C address makes it possible for a master device to send data to a particular slave device on the bus. Slave DevicesĮach slave device has an I2C address that is used to identify the device. I2C networks can have multiple master devices and slave devices. The master and slave devices are connected by a bus. The I2C NetworkĪn I2C network consists of a master device and a slave device. It covers all of the steps, diagrams, and code you need to get started.
#ARDUING WIRE LIBRARY DOWNLOAD#
BONUS: I made a quick start guide for this tutorial that you can download and go back to later if you can’t set this up right now.