Datasheet

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MT9D111__7_REV5.fm - Rev. B 2/06 EN
183 ©2004 Micron Technology, Inc. All rights reserved.
MT9D111 - 1/3.2-Inch 2-Megapixel SOC Digital Image Sensor
Appendix A: Two-Wire Serial Register Interface
Micron Confidential and Proprietary
16-Bit Read Sequence
A typical read sequence is shown in Figure 53. First the master writes the register
address, as in a write sequence. Then a start bit and the read address specify that a read
is about to happen from the register. The master clocks out the register data, eight bits at
a time. The master sends an acknowledge bit after each 8-bit transfer. The register
address should be incremented after every 16 bits is transferred. The data transfer is
stopped when the master sends a no-acknowledge bit.
Figure 53: READ Timing from R0x09:0; Returned Value 0x0284
8-Bit Write Sequence
To be able to write one byte at a time to the register, a special register address is added.
The 8-bit write is done by writing the upper 8 bits to the desired register, then writing the
lower 8 bits to the special register address (R0xF1:0). The register is not updated until all
16 bits have been written. It is not possible to update just half of a register. In Figure 54, a
typical sequence for 8-bit writes is shown. The second byte is written to the special regis-
ter (R0xF1:0).
Figure 54: WRITE Timing to R0x09:0—Value 0x0284
8-Bit Read Sequence
To read one byte at a time, the same special register address is used for the lower byte.
The upper 8 bits are read from the desired register. By following this with a read from the
special register (R0xF1:0), the lower 8 bits are accessed (Figure 55). The master sets the
no-acknowledge bits.
SCLK
S
DATA
0xBA Address
Start Start Stop
ACK ACK ACK ACK NACK
Reg0x09 0xBB Address 0000 0010 1000 0100
SCLK
S
DATA
0xBA Address 0xBA Address Reg0xF1 1000 0100
Start
Start Stop
ACK
ACK ACK
ACK ACK ACK
Reg0x09 0000 0010