Data Sheet

NAU7802 24-bit ADC
Nuvoton Confidential - 14 - Revision 1.7
8.3.1 2-Wire Protocol Convention
All 2-Wire interface operations must begin with a START condition, which is a HIGH-to-LOW transition
of SDIO while SCLK is HIGH. All 2-Wire interface operations are terminated by a STOP condition,
which is a LOW to HIGH transition of SDIO while SCLK is HIGH. A STOP condition at the end of a
read or write operation places the serial interface in standby mode.
An acknowledge (ACK), is a software convention is used to indicate a successful data transfer. To
allow for the ACK response, the transmitting device releases the SDIO bus after transmitting eight bits.
During the ninth clock cycle, the receiver pulls the SDIO line LOW to acknowledge the reception of the
eight bits of data.
Following a START condition, the master must output a device address byte. This consists of a 7-bit
device address, and the LSB of the device address byte is the R/W (Read/Write) control bit. When
R/W=1, this indicates the master is initiating a read operation from the slave device, and when R/W=0,
the master is initiating a write operation to the slave device. If the device address matches the address
of the slave device, the slave will output an ACK during the period when the master allows for the ACK
signal.
STOP
SCLK
SDIO
START
Figure 1: START and STOP
9
8
1
2 ...7
Acknowledge
SCLK
SDIO
Not Acknowledge
Figure 2: Acknowledge and NOT Acknowledge
Device
Address Byte
Control
Address Byte
Data Byte
0 1 0 1 0 1 0 R/W
A7 A6 A5 A4 A3 A2 A1 A0
D7 D6 D5 D4 D3 D2 D1 D0
Figure 3: Slave Address Byte, Control Address Byte, and Data Byte