TLC320AD81C Datasheet, PDF (17/47 Pages) Texas Instruments – Stereo Audio Digital Equalizer DC

2.8 Serial Control Interface
Control parameters for the TLC320AD81C are loaded with an I²C master interface. Information is loaded
into the registers defined in appendix A, Software Interface. The I²C bus uses two pins, SDA (data) and SCL
(clock), to communicate between integrated circuits in a system. This device may be addressed by sending
a unique 7-bit slave address plus R/W bit (1 byte). All compatible devices share the same pins via a
bidirectional bus using a wire-ANDed connection. A pullup resistor must be used to set the high level on the
bus. The TLC320AD81C operates in standard mode up to 100 kbps with as many devices on the bus as
desired up to the capacitance load limit of 400 pF. Additionally, the TLC320AD81C operates only in slave
mode; therefore, at least one device connected to the I²C bus with this device must operate in master mode.
2.8.1 I²C Protocol
The bus standard uses transitions on the data pin (SDA) while the clock is high to indicate a start and stop
condition. A high-to-low transition on SDA indicates a start, and a low-to-high transition indicates a stop.
Normal data bit transitions must occur within the low time of the clock period. These conditions are shown
in Figure 2–4. These start and stop conditions for the I²C bus are required by standard protocol to be
generated by the master. The master must also generate the 7-bit slave address and the read/write (R/W)
bit to open communication with another device and then wait for an acknowledge condition. The slave holds
the SDA bit low during the acknowledge clock period to indicate an acknowledgment. When this occurs, the
master begins transmitting. After each 8-bit word, an acknowledgment must be transmitted by the receiving
device. There is no limit on the number of bytes that may be transmitted between a start and stop condition.
When the last word has been transferred, the master must generate a stop condition to release the bus. A
generic data transfer sequence is shown in Figure 2–4.
SDA
7 Bit Slave Address R/W A 8 Bit Register Address (N) A ^{8 Bit Register Data For} A ^{8 Bit Register Data For} A
Address (N)
Address (N)
76 5 4 3 210
76 5 4 3 210
76 5 4 3 210
76 5 4 3 210
SCL
Start
Stop
Figure 2–4. Typical I²C Data Transfer Sequence
The definitions used by the I²C protocol are listed below.
Transmitter
Receiver
Master
Slave
Multi-master
Arbitration
Synchronization
The device that sends data
The device that receives data
The device that initiates a transfer, generates clock signals, and terminates the
transfer
The device addressed by the master
More than one master can attempt to control the bus at the same time without
corrupting the message.
Procedure to ensure the message is not corrupted when two masters attempt to
control the bus
Procedure to synchronize the clock signals of two or more devices
2–5