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What is bus capacitance in I2C?
The bus capacitance includes not only the capacitance between each signal line (clock and data) to return, it includes the input capacitance of each device attached to the bus. This input capacitance can usually be found in a device’s data sheet.
How many devices can be connected on I2C bus?
128 devices
I2C Device Addressing 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 device I2C bus?
The I2C bus is a standard bidirectional interface that uses a controller, known as the master, to communicate with slave devices. The physical I2C interface consists of the serial clock (SCL) and serial data (SDA) lines. Both SDA and SCL lines must be connected to VCC through a pull-up resistor.
What is the limitation for adding additional devices to a single I2C channel?
Each device on an i2c network has a 7-bit address, so a single network theoretically supports up to 128 slave devices.In practice though, the limit is much lower. i2c slave chips often support only 8 different bus addresses, no more than 8 of that chip can be attached to the same i2c network.
Why do we need I2C?
In short, when you need to establish short distance communication within the same board or device, you can use I2C. It requires only two bidirectional wires for transmitting and receiving information. I2C allows designers to establish two-way communication between multiple master ICs and slave ICs.
How does the I2C bus work?
I2C is a serial communication protocol, so data is transferred bit by bit along a single wire (the SDA line). Like SPI, I2C is synchronous, so the output of bits is synchronized to the sampling of bits by a clock signal shared between the master and the slave. The clock signal is always controlled by the master.
What are the features of I2C bus?
I2C has many important features worth mentioning. It supports multiple data speeds: Standard-mode (100 kbps), Fast-mode(400 kbps), Fast-mode plus, High-speed mode (3.4 Mbps), and Ultra Fast-mode (5.0 Mbps) I2C communications. Other features include: Built in collision detection.
How is bus capacitance determined in Philips I2C?
i2c bus capacitance. It is given in philips i2c specification that maximum number of devices connected to the bus is limited by bus capacitance.There is formula specified for pull up resistor but there is no formula to calculate bus capacitance.
What is the maximum capacitance of a bus?
As the number of devices connected to the bus increases, the bus capacitance also increases (I think the maximum allowable capacitance is 400pf). To bring the bus to a logic 1, a pull up resistor is connected on SDA and SCL lines.
Is there an upper limit to the I2C bus?
An i2c bus is limited mainly by the capacitance of the bus (and thus speed), and accessible device addresses. And physical board space. But there is no real upper limit, when you factor in bus buffers, extenders, repeaters, hubs, multiplexers, switches (or any other name for a device that can switch between multiple busses).
Why is capacitive coupling important in the I 2 C Bus?
The capacitive coupling between the I 2 C signal lines and the ground plane can be significant if the ICs are far from each other, or multiple ICs are on the I 2 C bus.