Rev. 1.00
148
September 11, 2018
Rev. 1.00
149
September 11, 2018
HT45F4050
A/D NFC Flash MCU
HT45F4050
A/D NFC Flash MCU
I
2
C Bus Data and Acknowledge Signal
The transmitted data is 8-bit wide and is transmitted after the slave device has acknowledged receipt
of its slave address. The order of serial bit transmission is the MSB first and the LSB last. After
receipt of 8
bits of data, the receiver must transmit an acknowledge signal, level "0", before it can
receive the next data byte. If the slave transmitter does not receive an acknowledge bit signal from
the master receiver, then the slave transmitter will release the SDA line to allow the master to send
a STOP signal to release the I
2
C Bus. The corresponding data will be stored in the SIMD register.
If setup as a transmitter, the slave device must first write the data to be transmitted into the SIMD
register. If setup as a receiver, the slave device must read the transmitted data from the SIMD register.
When the slave receiver receives the data byte, it must generate an acknowledge bit, known as
TXAK, on the 9th clock. The slave device, which is setup as a transmitter will check the RXAK bit
in the SIMC1 register to determine if it is to send another data byte, if not then it will release the
SDA line and await the receipt of a STOP signal from the master.
Start
SCL
SDA
SCL
SDA
1
S=Start (1 bit)
SA=Slave Address (7 bits)
SR=SRW bit (1 bit)
M=Slave device send acknowledge bit (1 bit)
D=Data (8 bits)
A=ACK (RXAK bit for transmitter, TXAK bit for receiver, 1 bit)
P=Stop (1 bit)
0
ACK
Slave Address
SRW
Stop
Data
ACK
1
1
0
1
0
1
0
1
0
0
1
0
1
0
0
S SA SR M D A D A
……
S SA SR M D A D A
……
P
I
2
C Communication Timing Diagram
Note: When a slave address is matched, the device must be placed in either the transmit mode
and then write data to the SIMD register, or in the receive mode where it must implement a
dummy read from the SIMD register to release the SCL line.