I used I☬1 in this example, hence, 'hi2c1' is used for the SSD1306_I2C_PORT definition.Take a look at 'ssd1306.h' header file, we have the following configurations and functions available: Stop condition: Stop conditions are defined by a low to high transition on SDA after a low to high transition on SCL, with SCL remaining high.Depending on the value of the R/W bit in address frame, data frame direction will be from slave to master and vice versa. Data frame(s): after the address frame has been transmitted by the master and acknowledged ‘ACK’ by the corresponding slave, it is followed by data frames.Since this is just a basic tutorial on I☬, we only consider 7-bit address case from now on in this tutorial. Only the slave which has the same address sends the ACK back to the master. The 9th bit of the frame is the NACK/ACK bit which is the case for all frames (data or address). Address frame: Each device class has a fixed 7-bit ‘device address’ which is used to identify itself from other devices in the same I☬ network followed by a R/W bit indicating whether this is a read (1) or write (0) operation.Start condition can be issued multiple times (repeat start) in case a master wants to retrieve more data from slaves. Start condition: the master device leaves SCL high and pulls SDA low, which informs all slave devices that a transmission is about to start.

The basic hardware connection for I2C communication (SCL, SDA).If you are not familiar with I2C, I suggest that you take a look at the tutorial on Sparkfun website and come back here with these information in mind: I found this article from Sparkfun describe in a very intuitive way and very easy to understand about the fundamentals of I2C.

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