I2C is a serial protocol for two-wire interface to connect low-speed devices like microcontrollers, EEPROMs, A/D and D/A converters, I/O interfaces and other similar peripherals in embedded systems. It was invented by Philips and now it is used by almost all major IC manufacturers.
SPI supports higher speed full-duplex communication while I2C is slower. I2C is cheaper to implement than the SPI communication protocol. SPI only supports one master device on the bus while I2C supports multiple master devices. I2C is less susceptible to noise than SPI.
There are plenty of ADCs that communicate via I2C. I2C is inherently a digital, low speed, serial communication bus. End devices need to be able to operate at 3.3 volts in order to interface with the Pi. The device can be analog in nature, but on board there is an ADC to convert signals to digital.
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.
UART is typically for a point to point connection, I2C is a bus protocol. UART is not a protocol (see also remark of Justme below), I2C is a protocol. UART is (can be) full duplex, I2C is not. UART does not have a master/slave principle (no protocol), I2C has.
I2C is the basis of the CAN bus. SPI (Serial Peripheral Interface) is a 3-wire, full duplex, master-slave serial bus. The main difference from I2C is that the lines are actively driven, so it can operate at much higher speeds. SPI has no such overhead or clock limitations, so it can be 80 or 100 times faster than I2C.
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. When sending out the 7 bit address, we still always send 8 bits. The extra bit is used to inform the slave if the master is writing to it or reading from it.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.
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.
You can start the testing process by verifying each of the following features on the I2C bus: START and STOP condition generation. A start condition is generated when the serial data (SDA) line switches from high voltage to low voltage before the serial clock (SCL) line switches from high to low.
I2C Interface
It is used to run signals between ICs mounted on the same PCB (Printed Circuit Board). It uses only two lines between multiple masters and multiple slaves viz. SDA (Serial Data) and SCL (Serial Clock). It is synchronous communication like SPI and unlike UART.I2C is a serial protocol for two-wire interface to connect low-speed devices like microcontrollers, EEPROMs, A/D and D/A converters, I/O interfaces and other similar peripherals in embedded systems. It was invented by Philips and now it is used by almost all major IC manufacturers.
You don't have a circuit without two connections, and for I2C, one of those connections is ground. If you build the above circuit (for SDA and another for SCL) you don't need to connect the grounds. Having the grounds common provides an enabling factor for disaster but does not really invite it with open arms.
For reference, shielded 22 AWG twisted pair cables have capacitance in the range of 100-240 pF/m. So the maximum bus length of an I2C link is about 1 meter at 100 Kbaud, or 10 meters at 10 Kbaud. Unshielded cable typically has much less capacitance, but should only be used within an otherwise shielded enclosure.
The I2C protocol is inherently half-duplex, while the SPI protocol is inherently full-duplex. So with SPI, every read is also a write. This could in theory double the speed of the bus, however, when implementing the SPI protocol we noticed that most of the time we didn't have data to send one direction.
The Controller Area Network (CAN bus) is the nervous system, enabling communication between all parts of the body. Similarly, 'nodes' are like muscles connected via the CAN bus, which acts as a central networking system. In turn, electronic control units (ECU) are like arms and legs.
I2C defines several speed grades but the term baud rate is quite unusual in this context. The speed grades (standard mode: 100 kbit/s, full speed: 400 kbit/s, fast mode: 1 mbit/s, high speed: 3,2 Mbit/s) are maximum ratings.
I2C is a serial protocol for two-wire interface to connect low-speed devices like microcontrollers, EEPROMs, A/D and D/A converters, I/O interfaces and other similar peripherals in embedded systems. It was invented by Philips and now it is used by almost all major IC manufacturers.
After sending the slave address: when the I2C master sends the address of the slave to talk to (including the read/write bit), a slave which recognizes its address sends an ACK. If no slave devices recognize the address, the result is a NACK.
I2C Pull Up Resistors. As discussed in the I2C Basics module, the resistors that are commonly seen on I2C circuits sitting between the SCL and SDA lines and the voltage source are called pull up resistors. A pull up resistor is used to provide a default state for a signal line or general purpose input/ouput (GPIO) pin.
3: Data was sent and a NACK received. This means the slave has no more to send. The master can send a STOP condition, or a repeated START. 4: Another twi error took place (eg, the master lost bus arbitration).
The I2C bus is a standard bidirectional interface that uses a controller, known as the master, to communicate with slave devices. A slave may not transmit data unless it has been addressed by the master. A bus is considered idle if both SDA and SCL lines are high after a STOP condition.
The general call address comprises of a slave address equal to 0000 000 followed by R/W = 0 and is reserved to implement special operations of devices. The general call address is for addressing every device connected to the I2C-bus at the same time.
Wire Library. The Wire library allows you to communicate with I2C devices, often also called "2 wire" or "TWI" (Two Wire Interface).
Acknowledgement (ACK) and No Acknowledgement (NCK) Condition. Each byte transmitted over the I2C bus is followed by an acknowledge condition from the receiver, which means, after the master pulls SCL low to complete the transmission of 8-bit, the SDA will be pulled low by the receiver to the master.
Each I2C command initiated by master device starts with a START condition and ends with a STOP condition. For both conditions SCL has to be high. A high to low transition of SDA is considered as START and a low to high transition as STOP.
Clock Stretching in I2C Bus. Clock stretching, sometimes referred to as clock synchronization, is a mechanism used by an I2C slave to notify the master to slow down the clock speed.
The two wires, or lines are called Serial Clock (or SCL) and Serial Data (or SDA). The SCL line is the clock signal which synchronize the data transfer between the devices on the I2C bus and it's generated by the master device. The other line is the SDA line which carries the data.
Serial Peripheral Interface (SPI) is an interface bus commonly used to send data between microcontrollers and small peripherals such as shift registers, sensors, and SD cards. It uses separate clock and data lines, along with a select line to choose the device you wish to talk to.
