HT46R221 Holtek Semiconductor Inc, HT46R221 Datasheet - Page 22

• Manufacturer Part Number: HT46R221
• Description: 8-Bit A/D Type MCU
• Manufacturer: Holtek Semiconductor Inc

SRW bit
The SRW bit means that the master device wants to
read from or write to the I
check this bit to understand itself if it is a transmitter or a
receiver. The SRW bit is set to 1 means that the mas-
ter wants to read data from the I
vice must write data to a bus as a transmitter. The SRW
is cleared to 0 means that the master wants to write
data to the I
device must read data from the I
Acknowledge bit
One of the slave device generates an acknowledge signal,
when the slave address is matched. The master device
can check this acknowledge bit to know if the slave device
accepts the calling address. If no acknowledge bit, the
master must send a STOP bit and end the communication.
When the I
means the address is matched, so the slave must check
SRW as a transmitter (set HTX) to 1 or as a receiver
(clear HTX) to 0 .
Data byte
The data is 8 bits and is sent after the slave device has
acknowledges the slave address. The first bit is MSB
and the 8th bit is LSB. The receiver sends the acknowl-
edge signal ( 0 ) and continues to receive the next 1
byte data. If the transmitter checks and there s no ac-
knowledge signal, then it release the SDA line, and the
master sends a STOP signal to release the I
The data is stored in the HDR register. The transmitter
must write data to the HDR before transmit data and the
receiver must read data from the HDR after receiving
data.
Rev. 1.10
2
C BUS status register bit 6 HAAS is high, it
2
C BUS, so the slave
2
C BUS. The slave device
2
C BUS, so the slave de-
2
C BUS as a receiver.
2
C BUS.
22
Receive acknowledge bit
When the receiver wants to continue to receive the next
data byte, it generates an acknowledge bit (TXAK) at
the 9th clock. The transmitter checks the acknowledge
bit (RXAK) to continue to write data to the I
change to receive mode and dummy read the HDR reg-
ister to release the SDA line and the master sends the
STOP signal.
Data stable and data allow change
Start bit
Stop bit
HT46R22/HT46C22
October 2, 2002
2
C BUS or