I2C (Inter-Integrated Circuit, aka IIC, Speak: Eye-Squared-See) is a synchronous bus system invented 1982 by Philips. Today, it is widely used to connect components to microcontrollers inside devices.
Since I2C is relatively slow, for components requiring higher data rates (such as color displays), SPI is used.
Quick Overview
I2C is a bus that is used to inter-connect components inside a device and over a short distance.
Here are its key benefits:
- GPIOs: requires just two GPIOs to connect up to 127 devices (SDA and SCL)
- Device Address: every device on the bus has a unique predefined address
And these are the most important limitations:
- Speed: in standard mode, speed is 100 kbit/s. There are faster modes (400 kbit/s, 1/3.4/5 MBit/s) that are not supported by all devices.
- Noise: Its high impedance and low noise immunity require a common ground and short distances.
- Address: Since addresses are often not fully configurable or even fixed, the already small 7-bit address space is further limited,effectively preventing the use of multiple components of the same kind (i.e. multi-display use cases).
Buffers and multiplexers can stretch the limits of I2C. Most of the time, switchting to a different bus system that is suited for the task (i.e. SPI) is a better approach.
I2C Address
I2C uses a 7-bit address to uniquely address invididual devices. Theoretically, this provides 127 unique device addresses.
Realistically, most components have fixed addresses or just a small number of selectable addresses. So the number of I2C devices on an I2C bus is much lower.
Hex vs. Binary vs. Decimal
I2C addresses can be specified in different formats.
- in binary format, the address bits are specified, i.e.
1000000. The true address is defined by two 4-bit values:0100 0000. In this example, these would be the numbers4and0, resulting in the I2C address40. - in hexadecimal format, the address is specified as
0x40 - in decimal format, the hexadecimal address is converted to the decimal system:
0x40can also be expressed as60.
The most commonly used format are hexadecimal addresses.
Materials
Slow Website?
This website is very fast, and pages should appear instantly. If this site is slow for you, then your routing may be messed up, and this issue does not only affect done.land, but potentially a few other websites and downloads as well. Here are simple steps to speed up your Internet experience and fix issues with slow websites and downloads..
Comments
Please do leave comments below. I am using utteran.ce, an open-source and ad-free light-weight commenting system.
Here is how your comments are stored
Whenever you leave a comment, a new github issue is created on your behalf.
-
All comments become trackable issues in the Github Issues section, and I (and you) can follow up on them.
-
There is no third-party provider, no disrupting ads, and everything remains transparent inside github.
Github Users Yes, Spammers No
To keep spammers out and comments attributable, all you do is log in using your (free) github account and grant utteranc.es the permission to submit issues on your behalf.
If you don’t have a github account yet, go get yourself one - it’s free and simple.
If for any reason you do not feel comfortable with letting the commenting system submit issues for you, then visit Github Issues directly, i.e. by clicking the red button Submit Issue at the bottom of each page, and submit your issue manually. You control everything.
Discussions
For chit-chat and quick questions, feel free to visit and participate in Discussions. They work much like classic forums or bulletin boards. Just keep in mind: your valued input isn’t equally well trackable there.
(content created Jul 07, 2024)