What do SCL and SDA stand for?
SCL is the clock line. It is used to synchronize all data transfers over the I2C bus. SDA is the data line. The SCL & SDA lines are connected to all devices on the I2C bus. There needs to be a third wire which is just the ground or 0 volts.
How many devices can be connected to 12c communication?
All of our modules and the common chips you will use will have 7 bit addresses. This means that you can have up to 128 devices on the I2C bus, since a 7bit number can be from 0 to 127.
What is 2 wire communication?
In telecommunication, a two-wire circuit is characterized by supporting transmission in two directions simultaneously, as opposed to four-wire circuits, which have separate pairs for transmit and receive.
Why is the SDA line held high instead of low?
Edit2: The SDA line, and SCL, is held high not low as I first incorrectly assumed (I probably did something wrong when I measured it and thought it was low but anyway.) The problem was that the resistors I was using as pull-up resistors were in fact 1k not 2k. I changed them for 2k resistors and the problem disappeared.
When do you change the state of SDA?
The state of SDA (high or low) can change only when SCL is low. This means SDA must be stable when SCL high. Sampling is done while the SCL going 0 to 1 state. Changing SDA when SCL is low provides some timing margin for accurate sampling.
When do you change the SDA on I2C?
Sampling is done while the SCL going 0 to 1 state. Changing SDA when SCL is low provides some timing margin for accurate sampling. As for I2C itself is a mutual interface standard. Both sides (TX and RX) can control the SDA line in different times.
What’s the minimum ILmax for a low voltage SDA?
V ILmax (the maximum input voltage to be considered low) is 0.3V. That means the range between 0.3V and 0.7V is unstable. Assuming you are operating in Standard-mode: SDA must be setup (moved to a stable range) 250ns before SCL goes high.