PAS302BCW-22S
CMOS Image Sensor IC
5.2Data Transfer Format
5.2.1 Master transmits data to slave (write cycle)
S : Start
A : Acknowledge by slave
P : Stop
RW : The LSB of 1st byte to decide whether current cycle is read or write cycle.
If RW=1 that means read cycle, if RW=0 that means write cycle.
SUBADDRESS : The address values of PAS302BCW-22S internal control registers
(Please refer to PAS302BCW-22S register description)
1ST BYTE
2ND BYTE
n BYTEs + A
S
SLAVE ID (7 BIT)
RW
A
SUBADDRESS (8 BIT)
A
DATA
A
DATA
A
P
MSB
LSB=0
During the write cycle, the master generates start condition and then places the 1st byte data
that combined slave address (7 bits) with a read/write control bit on SDA line. After
slave(PAS302BCW-22S) issues acknowledgment, the master places 2nd byte (sub-address)
data on SDA line. And then following the slave’s( PAS302BCW-22S) acknowledgment, the
master places the 8 bits data on SDA line and transmit to PAS302BCW-22S control register
(address was assigned by 2nd byte). After PAS302BCW-22S issue acknowledgment, the
master can generate a stop condition to end this write cycle. In the condition of multi-byte write,
the PAS302BCW-22S sub-address will be increased automatically after each DATA byte has
been transferred. The Data and A cycles are repeated until last byte write. Every control
registers value inside PAS302BCW-22S can be programming via this way. (Please refer to
Figure 5.3.)
5.2.2 Slave transmits data to master (read cycle)
The sub-address was assigned by previous write cycle
The sub-address is automatically increased after each byte read
Am : Acknowledged by master
Note: there is no acknowledgment from master after last byte read
1ST BYTE
2ND BYTE
n BYTE
Am
SLAVE ADDRESS
(7 BITS)
S
RW
A
DATA (8 BIT)
Am DATA
DATA
1
P
NO ACK IN LAST
BYTE
During read cycle, the master generates start condition and then place the 1st byte data that
combine slave address (7 bits) with a read/write control bit to SDA line. After slave issue
acknowledgment, 8 bits DATA was placed on SDA line by PAS302BCW-22S. The 8 bit data was
read from PAS302BCW-22S internal control register that address was assigned by previous
write cycle. Following the master acknowledgment, the PAS302BCW-22S place the next 8 bits
data (address is increased automatically) on SDA line and then transfer to master serially. The
Version 2.4, 20 Sep. 2005
PixArt Imaging Inc.
8
E-mail: fae_service@pixart.com.tw
PIXART [ PIXART IMAGING INC. ]
