Data Sheet

ISM14585-L35 Specification
DOC-DS-14585-201807-3.0
Confidential Inventek Systems
Page 32
9.7.1.1 BUS TRANSFER TERMS
The following terms are specific to data transfers that occur to/from the I2C bus:
• START (RESTART). Data transfer begins with a START or RESTART condition.
The level of the SDA data line changes from high to low, while the SCL clock line
remains high. When this occurs, the bus becomes busy.
• STOP. Data transfer is terminated by a STOP condition. This occurs when the
level on the SDA data line passes from the low state to the high state, while the
SCL clock line remains high. When the data transfer has been terminated, the
bus is free or idle once again. The bus stays busy if a RESTART is generated
instead of a STOP condition.
Note: START and RESTART conditions are functionally identical.
9.7.2 I2C BEHAVIOR
The I2C can be only be controlled via software to be an I2C master only,
communicating with other I2C slaves;
The master is responsible for generating the clock and controlling the transfer of data.
The slave is responsible for either transmitting or receiving data to/from the master. The
acknowledgement of data is sent by the device that is receiving data, which can be
either a master or a slave. As mentioned previously, the I2C protocol also allows
multiple masters to reside on the I2C bus and uses an arbitration procedure to
determine bus ownership.
Each slave has a unique address that is determined by the system designer. When a
master wants to communicate with a slave, the master transmits a START/RESTART
condition that is then followed by the slave’s address and a control bit (R/W) to
determine if the master wants to transmit data or receive data from the slave. The slave
then sends an acknowledge pulse (ACK) after the address.
If the master (master-transmitter) is writing to the slave (slave-receiver), the receiver
gets one byte of data. This transaction continues until the master terminates the
transmission with a STOP condition. If the master is reading from a slave (master-
receiver), the slave transmits (slave-transmitter) a byte of data to the master, and the